DOMS - Delayed Onset Muscle SorenessOverloading the muscle (unusual activities, unusually large range of motion, unusual number of repetitions) can result in delayed onset muscle soreness (DOMS), commonly felt from 12-48 hours following the activity. There may also be muscle stiffness, fatigue and weakness. These are caused by minor damage to (microscopic tearing of) the muscle cells, the associated inflammation and swelling. In response, the body repairs and rebuilds the muscle cells bigger and more capable of handling the load more efficiently the next time so the same activity will no longer result in soreness.

Here are some tips for treating delayed soreness:

Wait. Soreness will go away in 3 to 7 days with no special treatment. Avoid any vigorous activity that increases pain, but ... Do some easy low-impact aerobic exercise (Nia ) - this will increase blood flow to the affected muscles, which

may help diminish soreness. Use gentle stretching of the affected area. Gently massage the affected muscles.

Some pain can be a sign of a serious injury. If your muscle soreness does not get better within a week consult your physician.

Feet – The Hands that Touch the EarthFoot AnatomyThe human foot is a combined structure of base and lever, supporting and balancing the body’s weight while standing, as well as raising and moving the body forward when in motion. Our feet work for us the whole day, whether we stand, play, run, or walk, and in the process they become the most affected and often neglected part of our anatomy.

Parts of the FootThe foot is composed of 28 skeletal bones held together by 109 ligaments and 32 muscles and tendons, connected to the long bones of the leg (Tibia & Fibula) at the ankle joint.

Seven bones form the back of the foot, the hind foot. Distribution of weight is concentrated upon six basic points of support provided by the bone framework. The heel bone takes about half the weight.

Five slender bones located in the front of the instep make up the middle part of the foot. The two important functions weight bearing and propulsion require a high degree of stability. In addition, the foot must be flexible, so it can adapt to uneven surfaces. The multiple bones and joints of the foot give it flexibility, but these multiple bones must form an arch to support any weight. The foot has 1 main arch along the inside of the foot and 3 lesser arches: the metatarsal arch across the ball of the foot, the outer long arch down the outside of the foot and a short arch under the rear of the foot.

Fourteen bones form the toes. Their function is to grip, clamping the feet to the walking surface. They give final propulsion as the foot completes a step, shifting weight to the other foot. Although the big toe carries part of the body weight with each step, no weight rests on the big toe as the body stands. The toes’ gripping tendency helps to maintain balance and aid propulsion.

The Gait CycleDefinition:

The rhythmic alternating movements of the 2 lower extremities which result in the forward movement of the body. Simply stated, it is the manner in which we walk.

Phases:Stance (support) phase - begins when the heel of the forward limb makes contact with the ground and ends when the toe

of the same limb leaves the ground. heel strike - heel of forward foot touches the ground mid stance - foot is flat on the ground and the weight of the body is directly over the supporting limb. toe off - only the big toe of the forward limb is in contact with the ground.

Swing (unsupported) phase - begins when the foot is no longer in contact with the ground. The limb is free to move. acceleration - the swinging limb catches up to and passes the torso deceleration - forward movement of the limb is slowed down to position the foot for heel strike.

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Spine – Snake/undulation/supports the core/ our core supportThe spine is one of the most important parts of our body. Without it, we could not keep ourself upright or even stand up. It gives our body structure and support. It allows us to move about freely and to bend with flexibility. The spine is also designed to protect our spinal cord. The spinal cord is a column of nerves that connects our brain with the rest of our body, allowing us to control our movements. Without a spinal cord, we could not move any part of our body, and our organs could not function. This is why keeping our spine healthy is vital if we want to live an active life.

Anatomy

What exactly is the spine? Your spine is made up of 24 small bones (vertebrae) that are stacked on top of each other to create the spinal column. Between each vertebra is a soft, gel-like cushion called a disc that helps absorb pressure and keeps the bones from rubbing against each other. Each vertebra is held to the others by groups of ligaments. Ligaments connect bones to bones; tendons connect muscles to bones. There are also tendons that fasten muscles to the vertebrae. The spinal column also has real joints (just like the knee or elbow or any other joints) called facet joints. The facet joints link the vertebrae together and give them the flexibility to move against each other.

The spine itself has three main segments: the cervical spine, the thoracic spine, and the lumbar spine. The cervical is the upper part of the spine, made up of seven vertebrae (bones). The thoracic is the center portion of the spine, consisting of 12 vertebrae. The lower portion of the spine is called the lumbar spine. It is usually made up of five vertebrae, however, some people may have six lumbar vertebrae. Having six vertebrae does not seem to cause a problem. Below the lumbar spine is the sacrum. The sacrum is actually a group of specialized vertebrae that connects the spine to the pelvis. During development (those nine months before birth), these vertebrae grow together or fuse creating one large "specialized" vertebral bone that forms the base of your spine and center of your pelvis. The nerves that leave the spine in the sacral region control the bowel and bladder functions and give sensation (feeling) to the crotch area.

The normal spine has an "S"-like curve when looking at it from the side. This allows for an even distribution of weight. The "S" curve helps a healthy spine withstand all kinds of stress. The cervical spine curves slightly inward, the thoracic curves outward, and the lumbar curves inward. Even though the lower portion of your spine holds most of the body's weight, each segment relies upon the strength of the others to function properly.

Spinal Function and Anatomy

Function

The back is a complex network of muscles, ligaments, bones, joints, cartilage and nerves that work together to provide support and mobility to the body. The support allows one to stand, walk and lift. Mobility allows movements such as turning, twisting and bending. The body’s backbone, or spine, is a column of cylindrical bones that encases and protects the spinal cord, which controls every movement and function of the body. Motor nerves leading out of the spinal cord control movement in the body, while sensory nerves entering the spinal cord communicate messages from the body back to the brain. These motor and sensory nerves form nerve roots that run through passageways, or foramina, between the bones of the spine. These nerve roots may become irritated when spinal structures pinch or press against the roots.

Anatomy

The spine is a flexible column made up of cylindrical bone segments called vertebrae. These vertebrae are linked and hinged together by facet joints that protrude from the back of each vertebra’s body. Pedicles are the bony structures that connect the facet joints to the vertebral body. In between the vertebrae are intervertebral discs, which are gel-like cushions that increase spinal flexibility and absorb shock from everyday movements. Openings within each vertebra, called vertebral foramina, line up in succession to form the long hollow vertebral canal for the spinal cord. These openings also allow nerves from the spinal cord to branch out and exit the side of the spinal column.

When describing anatomy, medical professionals use terms that directly refer to the directional view of body parts. Two terms—anterior and posterior—are frequently used when surgeons discuss spinal surgery. Anterior refers to the front of the body or situated nearer the front of the body. Posterior refers to the back of the body or situated nearer the back of the body. Therefore, an anterior surgical approachenters through the front of the body.

The cervical spine supports the skull and allows for its rotation. The thoracic spine is firmly attached to the ribs and experiences little movement. The lumbar spine carries the most weight and experiences the most motion relative to other regions of the spine. These two factors make the lumbar spine the most frequent source of back pain. Below the lumbar spine, nine vertebrae grow together. Five form the triangular bone called the sacrum, which is held between the iliac bones of the pelvis on either side and serves to transfer the weight of the upper body to the legs. The lowest four vertebrae form the tailbone or coccyx, which is the terminal point at the base of the spine.

The spine is a flexible column made up of cylindrical bones called vertebrae that are stacked on top of each other.  These vertebrae are linked and hinged together by facet joints, which give them the flexibility to move against each other.  In between the vertebra are intervertebral discs, soft, gel-like cushions that keep the bones from rubbing against each other,

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increase spinal flexibility and absorb shock from everyday movements.  Openings within each vertebra, (vertebral foramina), line up in succession to form the long hollow vertebral canal for the spinal cord.  These openings also allow nerves from the spinal cord to branch out and exit the side of the spinal column.

The normal spine has an "S"-like curve when looking at it from the side.  This allows for an even distribution of weight. The "S" curve helps a healthy spine withstand all kinds of stress. The 7 smaller vertebrae of the cervical spine form a slightly inward curve.The 12 medium sized vertebrae of the thoracic spine each have a pair of ribs attached and curve outward.  In the front part of the body the ribs attach directly or indirectly to the sternum, thus forming the rib cage.  The rib cage protects the chest cavity and holds the heart and lungs. The 5 larger vertebrae of the lumbar area curve inward.  Even though the lower portion of the spine holds most of the body's weight, each segment relies upon the strength of the others to function properly.

Below the lumbar spine is the sacrum.  The sacrum is actually a group of specialized vertebrae that connects the spine to the pelvis.  During development (those nine months before birth), these vertebrae grow together or fuse creating one large "specialized" vertebral bone that forms the base of your spine and at the same time the "back wall" of your pelvis. The nerves that leave the spine in the sacral region control the bowel and bladder functions and give sensation (feeling) to the crotch area.

Joined to the sacrum by a flat, circular layer of fibrocartrilage (a strong type of tissue) is the coccyx.  The coccyx is all that is left of the tailbones of animals we evolved from.  At birth, the coccyx is made up of up to four separate small bones, but they join together by age 60, as if they were one bone.  The coccyx bones of men join together at an earlier time than women.

The Abdominals – Our Core SupportSeveral sets of muscles support the back, improve and help maintain posture and aid the spinal muscles with movement of the torso. They help transfer force between the upper and lower body, and they also protect the delicate internal organs. Keeping our spine healthy is vital if we want to live an active life, and there is a close relationship between our spine health and the strength of our “power house”.

Abdominal AnatomyThere are four muscle groups that make up the walls of our abdominal area power house, from the outside in:

The Rectus Abdominis – The rectus abdominis runs vertically along the front of our torso from the pubic bone to the sternum (inserting in the cartilage of the fifth, sixth, and seventh ribs). Activation of the rectus abdominis flexes the spine, pulls the rib cage and the pelvis towards each other and may affect the curvature of the lower back. It also tenses the abdominal wall and aids in compressing the contents of the abdomen. Strengthening the rectus abdominis will provide you with the "six pack" and enhance performance in sports requiring jumping, running, and lifting objects.

The External Obliques - The external obliques run diagonally to the rectus abdominis; from the lower ribs along the side of the torso and partly on the front to the rectus, the pubic bone, and the iliac crest of the hip (“front pocket”). These muscles aid in the twisting of the trunk, assist the rectus abdominis muscle in flexing the spine when the trunk twists or turns. They also support the abdominal organ tissue. The left external oblique is activated when twisting to the right, and the right external oblique is activated when twisting to the left.

The Internal Obliques - The internal obliques lie underneath the external obliques and run in a diagonally opposite direction (“back pocket”). These muscles protect a weak point in the abdominal wall and work with the external obliques to help twist the torso. The internal obliques aid the trunk in twisting in the same direction as the side they are on. Activation of external and internal obliques of the same side support the spinal lateral flexion (side-bend).

The Transverse Abdominis - The transverse abdominis (“girdle”, or “corset”) runs horizontally across the abdominal wall and along the midsection underneath the external and internal obliques. The muscle lies just below the internal oblique and spans the area from the pelvis and the lumbar region of the spine to the six lower ribs. The transverse abdominis pulls the abdominal wall inward, acts as a natural weight belt, keeps your insides in and assists in breathing (contraction supports expiration, i.e.,breathing out). This muscle is essential for trunk stability. Strengthening the transverse abdominis will enhance your posture and may alleviate back pain.

In addition to these traditionally listed abdominal muscles our power house relies on two more muscular features. The Pelvic Floor Muscles are a group of several small muscles that form a large sling (or hammock) of muscles stretching from side to side across the floor of the pelvis. They attach to the pubic bone in front, and to the coccyx (the tail end of the spine) behind thus forming your "undercarriage". The openings from bladder (urethra), bowels (rectum), and, in women, womb (vagina) all pass through the pelvic floor.

The pelvic floor muscles

support pelvic organs and abdominal contents, especially when standing or during contraction of the transversus abdominis

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support the bladder to help it stay closed, actively squeezing when coughing or sneezing to help avoid leakage - when the muscles are not working effectively you may suffer from leaking ("urinary incontinence"), and/or urgent or frequent need to pass urine

are used to control wind and when "holding on" with your bowels have an important sexual function, helping to increase sexual awareness both for yourself and your partner

during sexual intercourse

The Diaphragm is the dome-shaped muscle that forms the “roof” of your power house. It attaches to the bottom of the rib cage and separates the chest (thoracic) cavity from the abdomen. The diaphragm is the main muscle of respiration. Contraction of the diaphragm muscle creates a vacuum in the chest cavity and expands the lungs during inspiration (breathing in). We rely heavily on the diaphragm for our respiratory function so that when the diaphragm is impaired, it can compromise our breathing.

The Stomach is not part of the abdominal power house and therefore does not belong into this chapter.

Abdominal PhysiologySome of the abdominal muscles support spinal movement (rectus abdominis, external and internal obliques) and can thus be strengthened with exercises that move the spine in flexion, extension, lateral extension, rotation, undulation. Other muscles are more responsible for abdominal support and need to be exercised in a different way (Kegel exercises for pelvic floor muscles, breathing exercises for transverse abdominis and diaphragm). One very effective way to create the overload necessary for muscular growth in those muscles is the vocalizing in forceful expiration, or martial arts yell.Aside from a cheesy sound effect in a martial arts film a loud, guttural yell has other purposes. A proper yell gives a martial artist more focus and power to perform in proper technique. In addition, the exhalation, or thoracic grunt as practiced also by weightlifters or wrestlers, serves to equalize the pressure increase in the thorax which may result from violent exertion, thus preventing injury to the vital organs. When you yell as a result of tightening your abdominal muscles you are exhaling from the abdomen (diaphragm), expelling the majority of the tidal air (“margin of air” held in your lungs), moreso as with regular breathing, thus increasing the breathing or vital capacity of the lungs. You will then also be forced to breathe in, rather than to hold your breath. Holding your breath can cause a rise in pressure in the chest cavity, which in turn could cause the heart to go into fibrillation. That is, your heart stops beating rhythmically and that could eventually result in the heart stopping.

On a spiritual and emotional level, vocalizing such as yelling, yipping, grunting, sighing, promotes release of stress, tension, anger, aggression, etc.

The Skeletal SystemThe Skeletal System serves many important functions; it provides the shape and form for our bodies, protects organs, and anchors muscles, in addition to allowing bodily movement, producing blood for the body, and storing minerals (calcium). Adequate calcium consumption and weight bearing physical activity build strong bones, optimize bone mass, and may reduce the risk of osteoporosis later in life.

The human skeleton is divided into two distinct parts:

The axial skeleton consists of 80 bones that form the axis of the body and support and protect the organs of the head, neck, and trunk.

The Skull The Ribs and SternumThe Vertebral Column (Spine)

The appendicular skeleton is composed of 126 bones that form the appendages to the axial skeleton (limbs).

The Upper Extremities and Shoulder GirdleThe Lower Extremities and Pelvic Girdle--(the sacrum and coccyx are considered part of the vertebral column)

Types of BoneThe 206 bones of the body fall into four general categories: long bones, short bones, flat bones, and irregular bones. Long bones are longer than they are wide and work as levers. The bones of the upper extremities (i.e., humerus, ulna, radius, metacarpals, phalanges) and lower extremities (i.e., femur, tibia, fibula, metatarsals, phalanges) are of this type. Short bones are short, cube-shaped, and found in the wrists and ankles. Flat bones have broad surfaces for protection of organs and attachment of muscles (i.e., ribs, cranial bones, bones of shoulder girdle). Irregular bones are all others that do not fall into the previous categories. They have varied shapes, sizes, and surface features and include the bones of the vertebrae and a few in the skull.

Anatomy of Bone

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There are two main types of bone tissue. Compact, or cortical bone, which makes up most of the bone of arms and legs, is very dense and hard on the outside. The structural units of compact bone are osteons, elongated cylinders that act as weight-bearing pillars, able to withstand any mechanical stress placed on the bone. The center of each osteon contains a hollow canal that acts as a central passageway for blood vessels and nerves.

In some bones, internal to the compact bone is spongy bone, also known as cancellous bone, composed of a honeycomb network of structural units called trabeculae that act as supporting beams. Spongy bone is designed to bear stress from several directions, such as that exerted on the pelvis in bending or stretching. The spaces between the trabeculae are filled with red bone marrow containing the blood vessels that nourish spongy bone. Spongy bone is found in bones of the pelvis, ribs, breastbone, vertebrae, skull, and at the ends of the arm and leg bones.

The soft core of bone, the bone marrow, (red and active in children, yellow, fatty and inactive in adults) is the site of formation of red blood cells, certain white blood cells, and blood platelets. An average of 2.6 million red blood cells are produced each second by the bone marrow to replace those worn out and destroyed by the liver.

Surrounding both compact and spongy bone is a thin membrane, the periosteum. The inner layer of the periosteum consists mainly of osteoblasts (see “Physiology of Bone”). The outer layer of this membrane contains nerves and blood vessels that branch and travel into the bone. Ligaments and tendons may attach to the periosteum.

Intimately associated with bone is another type of connective tissue called cartilage. Cartilage covers the subchondral tissue, smooth tissue at the ends of bones. Cartilage is softer, more elastic, and more compressible than bone. It is found in body parts that require both stiffness and flexibility, such as the ends of bones, the tip of the nose, and the outer part of the ear. During the early development of a baby within its mother’s body, the skeletal structure consists of cartilage. During childhood, cartilage gradually is replaced by bone through the activity of osteoblasts (see “Physiology of Bone”). More than 300 bones are present in an infant, several of which fuse as the infant matures.

The point where two or more bones come together is called a joint, or articulation. Different kinds of joints enable different ranges of motion. Some joints barely move, such as those between the interlocking bones of the skull. Other bones, held together by tough connective tissues called ligaments, form joints such as the hinge joint in the knee, which permits movement in only one direction. The ball-and-socket joint of the hip allows movement of the femur against the pelvis in all three directions.

Physiology of the BoneBone is living tissue. Living bone cells are widely scattered within a nonliving material called the matrix. The matrix is formed by osteoblasts, cells that are constantly renewed in the bone. Osteoblasts make and secrete the protein collagen, which makes bones elastic so that they can give under the stresses generated by walking, lifting, and other activities. Osteoblasts also secrete mineral salts formed from calcium and phosphorus, which impart hardness so that bones do not break easily. If more bone is needed, new osteoblasts carry out the task of building it.

Throughout life, bone tissue undergoes continual breakdown and restoration in response to the body’s demands. The remodeling of bone requires the coordinated activity of two types of cells: osteoblasts to lay down new bone in their vicinity, and osteoclasts, that demineralize bone in their vicinity, absorb and remove unwanted tissue. Osteoclasts are derived from stem cells in the bone marrow.

For example, calcium must always be present in blood at a certain concentration. If calcium blood levels drop, osteoclasts break down bone to release calcium into the bloodstream. If exercise increases muscle mass, bones must thicken so that the pull of the stronger muscle does not break the bone. In this case, osteoblasts create new bone. The size and shape of bones not only change during growth, but for the rest of one's life it is continuously being remodeled in response to the stresses put on it. Approximately 10% of your bone mass is removed and replaced each year.

During childhood and adolescence, much more bone tissue is deposited than broken down, so the skeleton grows in size and strength. During early adulthood, breakdown slowly begins to exceed deposits. As a person ages, bone tissue is depleted, and bones are weakened and increasingly susceptible to breaks. Exercise and proper diet are critical for maintaining healthy bone growth at all stages of life. Nutrients - particularly sufficient calcium, phosphorus, and vitamin D, and hormones—including growth hormone, parathyroid hormone, calcitonin, and sex hormones—all influence bone growth.

Excess activity of osteoclasts (common after menopause in women) produces osteoporosis, one of the most common bone diseases which is characterized by a thinning of bone tissue, causing bones to become weak, brittle, and prone to fractures. The bones become weakened as cortical bone gets thinner and the spaces in spongy bone get larger. Before menopause, a woman needs about 1,000 mg of calcium per day. After menopause, she needs 1,000 mg of calcium per day if also taking estrogen and 1,500 mg of calcium per day if not taking estrogen. The body is more apt to absorb calcium from food than from supplements. Nonfat and low-fat dairy products are good sources of calcium. Other sources of calcium include dried beans, sardines and broccoli. About 300 mg of calcium are in each of the following: 1 cup of milk or yogurt, 2 cups of broccoli, or 6 to 7 sardines. Vitamin D and lactose (the natural sugar in milk) help the body absorb the

calcium. Many factors can cause osteoporosis, including menopause, lack of exercise, low calcium intake, smoking, use of steroid drugs, and excessive consumption of alcohol.

At about the eighth week of fetal development, calcium and phosphorus salts begin to deposit around the cartilage. At 40 weeks of development, however, the fetal bones still consist primarily of soft cartilage. The skull consists of several cartilage plates that are not completely joined. The spaces between the cartilage plates are called soft spots, or fontanels. The soft cartilage and the fontanels enable the skull to be compressed as it passes through the birth canal. Fractures, or breaks, are very common injuries to bones. The repair process requires the interplay of several processes. About a week after a fracture occurs, cells from the periosteum invade the damaged area and produce a fibrous network. Then, other cells produce cartilage in the network. Finally, osteoblasts enter the network and convert the cartilage to bone. Complete healing may take weeks or even months, depending on the individual’s general health, age, and other factors. Some fractures are treated with a splint, a firm object that supports the area surrounding the broken bone and restricts motion. Other fractures must be completely immobilized to heal because movement can cause a new fracture in the area. These fractures may be immobilized with a cast, plastic or plaster wrapped around the area that surrounds the broken bone. Dietary deficiencies of calcium, phosphorus, and vitamin D cause rickets, a disease characterized by abnormal bone formation and skeletal deformities. Rickets is most common in children. Dietary deficiencies of these nutrients in adults-or metabolic disorders that cause poor absorption of the nutrients-can result in an abnormal softening of bone, a condition called osteomalacia.Infections of bones called osteomyelitis usually are caused by bacteria, especially Staphylococcus, which enters the body through open wounds and may destroy bone tissues. Tumors, or abnormal growths, occur in bone tissue, though most are benign. Cancerous tumors can be caused by excessive radiation; many radioactive substances have an affinity for bone, particularly the marrow, and are readily stored there. Most cancerous tumors in bones, however, are tumors that spread from cancer in other parts of the body. Cancers that arise in bone, cartilage, and other connective tissues are called sarcomas. Functions

Bodily movement is carried out by the interaction of the muscular and skeletal systems. For this reason, they are often grouped together as the musculo-skeletal system. Muscles are connected to bones by tendons. Bones are connected to each other by ligaments. Where bones meet one another is typically called a joint. Muscles which cause movement of a joint are connected to two different bones and contract to pull them together. An example would be the contraction of the biceps and a relaxation of the triceps. This produces a bend at the elbow. The contraction of the triceps and relaxation of the biceps produces the effect of straightening the arm.Blood cells are produced by the marrow located in some bones. An average of 2.6 million red blood cells are produced each second by the bone marrow to replace those worn out and destroyed by the liver. Bones serve as a storage area for minerals such as calcium and phosphorus. When an excess is present in the blood, buildup will occur within the bones. When the supply of these minerals within the blood is low, it will be withdrawn from the bones to replenish the supply.

The Muscular SystemBodily movement is carried out by the interaction of the muscular and skeletal systems. For this reason, they are often grouped together as the musculo-skeletal system. Muscle is attached to bone by tendons and other tissues, and exerts force by converting chemical energy into tension and contraction. Skeletal muscles which cause movement of a joint are connected to two different bones and contract to pull them together.

Our bodily needs demand that muscles accomplish different chores, so we are equipped with three types of muscles.

Cardiac muscle, found only in the heart, powers the action that pumps blood throughout the body. Its big features are endurance and consistency.

Smooth muscle surrounds or is part of the internal organs. Smooth muscle is found in the digestive system, blood vessels, bladder, airways and, in a female, the uterus. It has the ability to stretch and maintain tension for long periods of time. Both cardiac and smooth muscles are called involuntary muscles, because they cannot be consciously controlled. (make a box or choose different font/colour and put in paragraph about stomach?)

Skeletal muscle carries out voluntary movements, and is what we use for movement in daily life and during exercise. The human body has more than 650 muscles, the body's most abundant tissue, comprising about 23% of a woman's body weight and about 40% of a man's body weight. Skeletal muscles can do a short, single contraction (twitch) or a long, sustained contraction (tetanus), and might ache after strenuous exercise.

Anatomy of Skeletal MuscleA skeletal muscle is composed of skeletal muscle tissue, nervous tissue, blood, and connective tissues. Fascia covers the surface of the muscle and also forms the cordlike tendons which attach the muscle to the bone. Epimysium lies beneath the fascia, and perimysium extends into the structure of the muscle, where it separates muscle tissue into small compartments of bundles of skeletal muscle fibers called fascicles. Endomysium separates individual muscle fibers within those fascicles. Blood vessels and axons of nerve cells lie within those connective tissues.

A skeletal muscle fiber is a single, thin, long cell that may extend the full length of the muscle. Just beneath its cell membrane (sarcolemma), the cytoplasm (sarcoplasm) of the fiber contains many threadlike myofibrils that lie parallel to one another. Each myofibril consists of repeating units called sarcomeres. The characteristic dark and light striations of a sarcomere are due to the arrangement of two kinds of protein filaments: thick filaments composed of the protein myosin and thin ones mainly composed of the protein actin.

According to the sliding filament model, myosin cross-bridges attach to a binding site on the actin filament and bend slightly, thus pulling on the actin filament. The filaments slide past one another, thus shortening the sarcomeres, thus shortening the myofibrils, thus shortening the muscle fiber. Then the head of the myosin cross-bridge can release, straighten, combine with another binding site further down the actin filament, and pull again, thus shortening the sarcomere, (myofibril and muscle fiber) more. This process can be repeated for as long as the muscle fiber is stimulated, or until the point of maximum shortening of the sarcomere. The actions of the myosin molecules are not synchronized -- at any given moment, some myosins are attaching to the actin filament, others are creating force (pulling) and others are releasing the actin filament). When the muscle fiber is no longer stimulated, the cross-bridges break down, and the muscle fiber relaxes.

Along side (in parallel) with the regular muscle fibers are muscle spindles or stretch receptors, the primary proprioceptors in the muscle. They undergo the same length changes as the rest of the muscle and thus measure the change in muscle length and the rate of change in muscle length. In the tendon of the muscle is located the Golgi tendon organ. It is sensitive to the change in tension and the rate of change of the tension, i.e., force the muscle exerts.

Physiology of Skeletal MuscleA muscle fiber contracts only when stimulated by its nerve, the motor neuron. A nerve impulse from the motor neuron translates into a muscle impulse that affects the whole muscle fiber at once, for as long as the stimulation continues. A stimulated skeletal muscle fiber responds to its fullest extend, i.e., it has an all-or-none response. While each muscle fiber is connected to only one axon of a motor neuron, a motor neuron may have many densely branched axons,

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The stomach is an organ of the alimentary canal, a muscular tube that forms part of the digestive system. The wall of the stomach contains smooth muscle tissue. Contractions of the smooth muscles of the alimentary canal serve to mix food with digestive juices, and to move the resulting mixture further along (peristalsis). Smooth muscles are called involuntary muscles, because they cannot be consciously controlled. As we have no control over the smooth muscle tissue of the stomach, we cannot consciously contract it, or “exercise” it. Therefore, there are no “exercises to strengthen the stomach” or “using the stomach to move the spine”.

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connecting to many muscle fibers, constituting a motor unit. When a motor neuron transmits an impulse, all the muscle fibers it links to are stimulated to contract simultaneously, and also in an all-or-none response.

A whole muscle is composed of many motor units controlled by different motor neurons, which respond to different thresholds of stimulation. If only the motor neurons with low thresholds are stimulated, few motor units contract, and the muscle contracts with minimal tension. At higher intensities of stimulation, additional motor neurons respond, and more motor units are activated, which produces a stronger muscle contraction. Such an increase in the number of motor units being activated is called recruitment. As the intensity of stimulation increases, recruitment of motor units continues until, finally, all possible motor units in that muscle are activated and the muscle contracts with maximal tension.

A single stimulus of threshold strength activates some of a muscle’s motor units, which makes the muscle contract and then relax. This action lasts only a fraction of a second and is called a twitch. The response time between stimulation and muscle reaction determines the classification into fast twitch or slow twitch fibers. Fast-twitch fibers are capable of developing greater forces, contracting faster to produce bursts of power and have greater anaerobic capacity. In contrast, slow-twitch fibers develop force slowly, can maintain contractions longer, have greater endurance and higher aerobic capacity. The skeletal muscles of an average person contain about half fast twitch and half slow twitch muscle fibers. Certain athletic activities promote increased percentage of fast twitch muscle fibers (Olympic sprinter), or slow twitch muscle fibers (Olympic marathoner).

A muscle fiber exposed to a series of stimuli of increasing frequency reaches a point when it is unable to completely relax before the next stimulus in the series arrives. When this happens, the force of individual twitches combines, a process called summation. When the resulting forceful, sustained contraction lacks even partial relaxation, it is called a tetanic contraction (tetanus). Summation and recruitment together can produce a sustained contraction of increasing strength. Although twitches may occasionally occur in skeletal muscles (e.g., eyelid twitch), such contractions are of limited use. More commonly muscular contractions are sustained.

Even when a muscle appears to be at rest, a certain amount of sustained contraction is occurring in a small fraction of the total number of its fibers. This muscle tone is important particularly in maintaining posture, and also enables the muscle to resist passive elongation or stretch.

When the muscle is stretched, so is the muscle spindle, which records the change in length (and how fast) and sends signals to the spine which convey this information. This triggers the stretch reflex which attempts to resist the change in muscle length by causing the stretched muscle to contract. The more sudden the change in muscle length, the stronger the muscle contractions will be (plyometric, or "jump", training is based on this fact). This basic function of the muscle spindle helps to maintain muscle tone and to protect the body from injury. However, ballistic stretching may cause a muscle contraction so strong it tears the muscle fibers or tendons, causing injury. One of the reasons for holding a stretch for a prolonged period of time (static stretching) is that as the muscle is held in a stretched position, the muscle spindle becomes accustomed to the new length and reduces its signaling. Gradually, you can train your stretch receptors to allow greater lengthening of the muscles.

When muscles contract (possibly due to the stretch reflex), they produce tension at the point where the muscle is connected to the tendon, where the golgi tendon organ is located. The Golgi tendon organ records the change in tension, and the rate of change of the tension, and sends signals to the spine to convey this information. When this tension exceeds a certain threshold, it triggers the lengthening reaction which inhibits the muscles from contracting and causes them to relax. This basic function of the golgi tendon organ helps to protect the muscles, tendons, and ligaments from injury. The lengthening reaction is possible only because the signaling of golgi tendon organ to the spinal cord is powerful enough to overcome the signaling of the muscle spindles telling the muscle to contract. Another reason for holding a stretch for a prolonged period of time is to allow this lengthening reaction to occur, thus helping the stretched muscles to relax. It is easier and more beneficial to stretch, or lengthen, a muscle when it is not trying to contract.

Skeletal Muscle ActionThe contraction of a muscle does not necessarily mean that the muscle shortens; it only means that tension has been generated. When muscles do cause a limb to move through the joint's range of motion, they usually act in the following cooperating groups:

agonists - These muscles cause the movement to occur. They create the normal range of movement in a joint by contracting. Agonists are also referred to as prime movers since they are the muscles that are primarily responsible for generating the movement.

antagonists - These muscles act in opposition to the movement generated by the agonists and are responsible for returning a limb to its initial position.

synergists - These muscles assist the agonist and make its action more effective by helping to hold the joint steady and keeping the two bones around the joint aligned. Synergists are also sometimes called stabilizers.

Muscles can contract in the following ways:

isometric contraction - This is a contraction in which no movement takes place, because the load on the muscle exceeds the tension generated by the contracting muscle. This occurs when a muscle attempts to push or pull an immovable object.

isotonic contraction - This is a contraction in which movement does take place, because the tension generated by the contracting muscle exceeds the load on the muscle. This occurs when you use your muscles to successfully push or pull an object. Isotonic contractions are further divided into two types:

o concentric contraction - This is a contraction in which the muscle decreases in length (shortens) against an opposing load, such as lifting a weight up. During a concentric contraction, the muscles that are shortening serve as the agonists and hence do all of the work.

o eccentric contraction - This is a contraction in which the muscle increases in length (lengthens) as it resists a load, such as returning a weight to starting position, or resisting a stretch. During an eccentric contraction the muscles that are lengthening serve as the agonists (and do all of the work).

As a result of excessive use, muscles may hypertrophy, that is, increase in size because of an increase in size of the individual muscle cells. As a result of prolonged disuse, muscles may atrophy, or diminish in size, and become weaker.

The Stomach is not considered part of the abdominal power house and therefore does not actually belong into this chapter. The stomach is an organ of the alimentary canal, a muscular tube that forms part of the digestive system. The wall of the stomach contains smooth muscle tissue. Smooth muscles are called involuntary muscles, because they cannot be consciously controlled. As we have no control over the smooth muscle tissue of the stomach, we cannot consciously contract it, or “exercise” it. Therefore, there are no “exercises to strengthen the stomach” or “using the stomach to move the spine”. Contraction of the smooth muscles of the alimentary canal serves to mix food with digestive juices, and to move the resulting mixture further along (peristalsis). ( put under power house)

Contracting a MuscleWhile the sliding of filaments explains how the muscle shortens, it does not explain how the muscle creates the force required for shortening. To understand how this force is created, let's think about how you pull something up with a rope:

1. Grab the rope with both hands, arms extended. 2. Loosen your grip with one hand, let's say the left hand, and maintain your grip with the right. 3. With your right hand holding the rope, change your right arm's shape to shorten its reach and pull the rope

toward you. 4. Grab the rope with your extended left hand and release your right hand's grip. 5. Change your left arm's shape to shorten it and pull the rope, returning your right arm to its original extended

position so it can grab the rope. 6. Repeat steps 2 through 5, alternating arms, until you finish.

To understand how muscle creates force, let's apply the rope example.

Myosin molecules are golf-club shaped. For our example, the myosin clubhead (along with the crossbridge it forms) is your arm, and the actin filament is the rope:

1. During contraction, the myosin molecule forms a chemical bond with an actin molecule on the thin filament (gripping the rope). This chemical bond is the crossbridge. For clarity, only one cross-bridge is shown in the figure above (focusing on one arm).

2. Initially, the crossbridge is extended (your arm extending) with adenosine diphosphate (ADP) and inorganic phosphate (Pi) attached to the myosin.

3. As soon as the crossbridge is formed, the myosin head bends (your arm shortening), thereby creating force and sliding the actin filament past the myosin (pulling the rope). This process is called the power stroke. During the power stroke, myosin releases the ADP and Pi.

4. Once ADP and Pi are released, a molecule of adenosine triphosphate (ATP) binds to the myosin. When the ATP binds, the myosin releases the actin molecule (letting go of the rope).

5. When the actin is released, the ATP molecule gets split into ADP and P i by the myosin. The energy from the ATP resets the myosin head to its original position (re-extending your arm).

6. The process is repeated. The actions of the myosin molecules are not synchronized -- at any given moment, some myosins are attaching to the actin filament (gripping the rope), others are creating force (pulling the rope) and others are releasing the actin filament (releasing the rope).

Isotonic vs. Isometric ContractionThe shortening of the fibers creates mechanical force, or muscle tension. Whether the muscle itself changes length (same-force or isotonic contraction) or not (same-length or isometric contraction) depends upon the load attached to the muscle. For example, your biceps muscle is attached to your shoulder blade at one end and to your ulna in your forearm at the other end. When the biceps contracts, it shortens and pulls the ulna toward the shoulder blade (the ulna is attached to the elbow joint). This movement allows you to lift your forearm and a given load. In contrast, if you are carrying a heavy load, such as a full suitcase, that makes you unable to lift your forearm, then the biceps does not shorten

significantly. But the force that the muscle generates is helping you carry the suitcase. Triggering ContractionThe contractions of all muscles are triggered by electrical impulses, whether transmitted by nerve cells, created internally (as with a pacemaker) or applied externally (as with an electrical-shock stimulus). The electrical signal sets off a series of events that lead to crossbridge cycling between myosin and actin, which generates force. The series of events is slightly different between skeletal, smooth and cardiac muscle. Let's describe the events in skeletal muscle first.

Let's take a look at what occurs within a skeletal muscle, from excitation to contraction to relaxation:

1. An electrical signal (action potential) travels down a nerve cell, causing it to release a chemical message (neurotransmitter) into a small gap between the nerve cell and muscle cell. This gap is called the synapse.

2. The neurotransmitter crosses the gap, binds to a protein (receptor) on the muscle-cell membrane and causes an action potential in the muscle cell.

3. The action potential rapidly spreads along the muscle cell and enters the cell through the T-tubule. 4. The action potential opens gates in the muscle's calcium store (sarcoplasmic reticulum). 5. Calcium ions flow into the cytoplasm, which is where the actin and myosin filaments are. 6. Calcium ions bind to troponin-tropomyosin molecules located in the grooves of the actin filaments.

Normally, the rod-like tropomyosin molecule covers the sites on actin where myosin can form crossbridges. 7. Upon binding calcium ions, troponin changes shape and slides tropomyosin out of the groove, exposing

the actin-myosin binding sites. 8. Myosin interacts with actin by cycling crossbridges, as described previously. The muscle thereby creates

force, and shortens. 9. After the action potential has passed, the calcium gates close, and calcium pumps located on the

sarcoplasmic reticulum remove calcium from the cytoplasm. 10. As the calcium gets pumped back into the sarcoplasmic reticulum, calcium ions come off the troponin. 11. The troponin returns to its normal shape and allows tropomyosin to cover the actin-myosin binding sites on

the actin filament. 12. Because no binding sites are available now, no crossbridges can form, and the muscle relaxes.

As you can see, muscle contraction is regulated by the level of calcium ions in the cytoplasm. In skeletal muscle, calcium ions work at the level of actin (actin-regulated contraction). They move the troponin-tropomyosin complex off the binding sites, allowing actin and myosin to interact.

Energy Systems for Muscle Contraction Most metabolic processes of the body use chemical energy (as compared to heat, light, sound, electrical or mechanical energy). The energy “currency” used by the body is Adenosine Triphosphate (ATP). The energy is stored in the bonds between the 3 phosphate groups. When energy is required for a metabolic reaction, the terminal phosphate bond breaks, releasing the stored energy. ATP thus converts to ADP (Adenosine Diphosphate) and energy. In reverse, ADP can be converted back into ATP by the addition of energy and a third phosphate. ADP can also set free a smaller amount of energy when splitting off the second phosphate group and converting to AMP (Adenosine Monophosphate) and energy. (see Metabolism for more detail on energy production). Again, this process is reversible and energy can be stored with the addition of energy and a phosphate, converting AMP to ADP.

The immediate source of energy for muscle contraction is ATP. Although a muscle fiber contains only enough ATP to power a few twitches, its ATP "pool" is replenished as needed. There are three essential metabolic systems to supply high-energy phosphate to keep the ATP pool filled.

Phosphagen System using creatine phosphate Glycogen Lactic Acid System using glycogen Cellular Respiration in the mitochondria of the fibers.

Creatine phosphate

The phosphate group in creatine phosphate is attached by a "high-energy" bond like that in ATP. Creatine phosphate derives its high-energy phosphate from ATP and can donate it back to ADP to form ATP, but it can not directly supply energy to a cell’s energy-utilizing reactions.

Creatine phosphate + ADP ↔ creatine + ATP

The pool of creatine phosphate in the fiber can be up to 10 times larger than that of ATP and thus serves as a modest reservoir of ATP. Together, the cell ATP and cell creatine phosphate molecules make up the Phosphagen Energy System. Active muscle, however, rapidly (within 8-10 seconds) exhausts the supply of creatine phosphate and muscle cells must rely on the other sources to replenish ATP.

Glycogen

Skeletal muscle fibers contain about 1% glycogen. The muscle fiber can degrade this glycogen by glycogenolysis anaerobic respiration) producing glucose-1-phosphate. This enters the glycolytic pathway to yield two molecules of ATP for each pair of lactic acid molecules produced. Not much, but enough to keep the muscle functioning if it fails to receive sufficient oxygen to meet its ATP needs by respiration.

However, this source is limited and eventually the muscle must depend on cellular respiration.

Cellular respirationCellular (aerobic) respiration not only is required to meet the ATP needs of a muscle engaged in prolonged activity (thus causing more rapid and deeper breathing), but is also required afterwards to enable the body to resynthesize glycogen from the lactic acid produced earlier (deep breathing continues for a time after exercise is stopped). The body must repay its oxygen debt.

Muscles use energy in the form of ATP. The energy from ATP is used to reset the myosin crossbridge head and release the actin filament. To make ATP, the muscle does the following:

1. Breaks down creatine phosphate, adding the phosphate to ADP to create ATP 2. Carries out anaerobic respiration, by which glucose is broken down to lactic acid and ATP is formed

3. Carries out aerobic respiration, by which glucose, glycogen, fats and amino acids are broken down in the presence of oxygen to produce ATP (see How Exercise Works for details).

The CardioRespiratory SystemTo function, each cell of the body needs a supply of energy and oxygen, and needs to dispose of the by-products of metabolism and CO2. Several systems have to work together: Nutrients and “waste” molecules are suspended in the liquid medium of blood (plasma). O2 and CO2 molecules can attach to red blood cells. The heart is the “engine” that pumps the blood through the vessels of the circulatory system. The blood, heart and blood vessels working together form the cardiovascular system. The gas exchange between the atmosphere and the body, i.e., obtaining O2 and removing CO2 from the blood, are the primary functions of the respiratory system. Efficiency of all those systems is essential. Regular aerobic exercise can improve cardio-respiratory capacity.

BloodBlood consists of a liquid portion called plasma (about 55%) and formed elements (about 45%) that include red blood cells, white blood cells, and platelets. Plasma is a complex mixture of water (about 92%), amino acids, proteins, carbohydrates, lipids, vitamins, hormones, electrolytes, and cellular wastes. Functions of plasma constituents include transporting nutrients, gases, and vitamins; helping regulate fluid and electrolyte balance; and maintaining a favourable pH.

The blood performs a lot of important functions. By means of the hemoglobin contained in the erythrocytes, it carries oxygen to the tissues and collects the carbon dioxide (CO2). It also conveys nutritive substances (e.g. amino acids, sugars, mineral salts) and gathers the excreted material which will be eliminated through the renal filter. The blood also carries hormones, enzymes and vitamins. It performs the defense of the organism by mean of the phagocitic activity of the leukocytes, the bactericidal power of the serum and the immune response of which the lymphocytes are the protagonists.

The main function of platelets, or thrombocytes, is to stop the loss of blood from wounds (hematostasis). Platelets (thrombocytes) are small cell fragments without a nucleus. They are capable of amoeboid movement and may circulate for about ten days. Platelets help close breaks in damaged blood vessels and initiate formation of blood clots, thus playing an important role in the body’s way to control blood loss from broken vessels.

White Blood Cells (leukocytes) are responsible for the defense of the organism by protecting against infection in various ways. Normally, five types of white blood cells are in circulating blood. They differ in size, certain characteristics and thus their functions. Some phagocytize (“cell-eating”) bacterial cells in the body. Others produce proteins (antibodies) that destroy or disable foreign particles, an important function of our immune system. Certain leukocytes help control inflammation and allergic reactions by removing bio-chemicals associated with these reactions. More contain a blood-clot-inhibiting substance, which helps prevent intravascular blood clot formation. Others release histamines which increase blood flow to injured tissues.

The erythrocytes are the most numerous blood cells i.e. about 4-6 millions/mm3. They are also called red cells. In man and in all mammals, erythrocytes are devoid of a nucleus and have the shape of a biconcave lens. In the other vertebrates (e.g. fishes, amphibians, reptilians and birds), they have a nucleus. The red cells are rich in hemoglobin, a protein able to bind in a faint manner to oxygen. Hence, these cells are responsible for providing oxygen to tissues and partly for recovering carbon dioxide produced as waste. However, most CO2 is carried by plasma, in the form of soluble carbonates.

In the red cells of the mammalians, the lack of nucleus allows more room for hemoglobin and the biconcave shape of these cells raises the surface and cytoplasmic volume ratio. These characteristics make more efficient the diffusion of oxygen by these cells. In so-called "sickle-cell anaemia", erythrocytes become typically sickle-

shaped. With the electron microscope, biologists saw that red cells can have different shapes: normal (discocyte), berry (crenated), burr (echinocyte), target (codocyte), oat, sickled, helmet, pinched, pointed, indented, poikilocyte, etc. The mean life of erythrocytes is about 120 days. When they come to the end of their life, they are retained by the spleen where they are phagocyted by macrophages.

LEUKOCYTES (white cells)

Leukocytes, or white cells, are responsible for the defense of the organism. In the blood, they are much less numerous than red cells. The density of the leukocytes in the blood is 5000-7000 /mm3. Leukocytes divide in two categories: granulocytes and lymphoid cells or agranulocytes. The term granulocyte is due to the presence of granules in the cytoplasm of these cells. In the different types of granulocytes, the granules are different and help us to distinguish them. In fact, these granules have a different affinity towards neutral, acid or basic stains and give the cytoplasm different colors. So, granulocytes distinguish themselves in neutrophil, eosinophil (or acidophil) and basophil. The lymphoid cells, instead, distinguish themselves in lymphocytes and monocytes. As we will see later, even the shape of the nucleus helps us in the recognition of the leukocytes.

Each type of leukocyte is present in the blood in different proportions:

neutrophil 50 - 70 %eosinophil 2 - 4 %basophil 0,5 - 1 %lymphocyte 20 - 40 %monocyte 3 - 8 %

Most lymphocytes circulating in the blood is in a resting state. They look like little cells with a compact round nucleus which occupies nearly all the cellular volume. As a consequence, the cytoplasm is very reduced. The lymphocytes of the lymphoid tissues and organs can be activated in a different amount following antigenic stimulation. In the blood, lymphocytes are 20-40 % of all leukocytes and are slight larger than red blood cells.

The lymphocytes are the main constituents of the immune system which is a defense against the attack of pathogenic micro-organisms such as viruses, bacteria, fungi and protista. Lymphocytes yield antibodies and arrange them on their membrane. An antibody is a molecule able to bind itself to molecules of a complementary shape called antigens, and recognize them. As for all proteins, even the antibodies are coded by genes. On the basis of a recombination mechanism of some of these genes, every lymphocyte produces antibodies of a specific shape.

Red Blood Cells (erythrocytes) are the most numerous blood cells. They are produced in the red bone marrow of long bones, and circulate for about 120 days, after which they are broken down in the liver and spleen. The absence of a nucleus gives them the shape of a biconcave lens. They are rich in hemoglobin (about 1/3 by volume), a protein able to bind in a faint manner to oxygen. Hence, red blood cells are responsible for providing oxygen to tissues and partly for recovering carbon dioxide produced as waste. However, most CO2 is carried by plasma, in the form of soluble carbonates. Hemoglobin and red blood cell production require a small supply of iron from food.

Too little hemoglobin (for example due to a lack of iron in the diet) or too few red blood cells cause anemia which reduces the O2-carrying capacity of blood. An affected person may appear pale and lack energy.

The hormone erythropoietin (EPO) is the main stimulus for red blood cell formation. Hypoxia – decreased oxygen levels in the tissues due to smoking or a sojourn at high altitude spurs the release of this hormone in larger-than-normal quantities. Consequently, red blood cell production is increased up along with the formation of hemoglobin. The process takes about 30 days to complete.

On average, your body has about 5 liters (5.3 quarts) of blood continually traveling through it by way of the circulatory system.

Circulatory (Cardiovascular) System

Blood is pumped through the body by the heart. It follows a winding course through the right chambers of the heart, into the lungs, where it picks up oxygen, and back into the left chambers of the heart (pulmonary circulation). From these it is pumped into the main artery, the aorta, which branches into increasingly smaller arteries until it passes through the smallest, known as arterioles. Beyond the arterioles, the blood passes through a vast amount of tiny, thin-walled structures called capillaries. Here, the blood gives up its oxygen and its nutrients to the tissues and absorbs from them carbon dioxide and other waste products of metabolism. The blood completes its circuit by passing through small veins that join to form increasingly larger vessels until it reaches the largest veins, the inferior and superior venae cavae, which return it to the right side of the heart (systemic circulation). Valves in the heart and in the veins ensure blood flow in only one direction.

Blood is propelled mainly by contractions of the heart. The organ is composed primarily of cardiac muscle tissue, that continuously contracts and relaxes. Like the smooth muscle tissue of the intestines, cardiac muscles are involuntary muscles that cannot be consciously controlled. (see Chapter: Skeletal Muscle). As the cardiac muscles can never rest in their rhythmic contractions, the heart must have a constant supply of oxygen and nutrients. The coronary arteries are the network of blood vessels that carry oxygen- and nutrient-rich blood to the cardiac muscle tissue (cardiac circulation). Blockage in those coronary arteries can trigger a cardiac event (heart attack).

Contractions of skeletal muscle also contribute to circulation, supporting the work done by the heart. That is why it is important to keep moving (engaging skeletal muscles) during “rest periods” during CV workout...

The body's circulatory system really has three distinct parts: pulmonary circulation, coronary circulation, and systemic circulation. Or, the lungs (pulmonary), the heart (coronary), and the rest of the system (systemic). Each part must be working independently in order for them to all work together.

A typical person has around 4-5 litres of blood. The blood is the transport system by which oxygen and nutrients reach the body's cells, and waste materials are carried away. In addition, blood carries substances called hormones, which control body processes, and antibodies to fight invading germs. The heart, a muscular organ, positioned behind the ribcage and between the lungs, is the pump that keeps this transport system moving.

 

   Your heart is about the size of your clenched fist. It has thick muscular walls and is divided into two pumps. Each pump has two chambers. The upper, smaller, thin-walled atrium receives blood coming in from the veins. The blood flows through a one-way valve, which makes sure it always moves in the correct direction, into the larger, lower chamber called the ventricle. It has thick strong walls that contract to squeeze blood through another valve, out into the arteries.

CVSysEss.jpgheart.jpg

Two-part Circulation

The body's circulation has two parts, with the heart acting as a double pump. Blood from the right side pump is dark red (bluish) and low in oxygen. It travels along pulmonary arteries to the lungs where it receives fresh supplies of oxygen and becomes bright red. It flows along pulmonary veins back to the heart's left side pump.

 

 

Blood leaves the left side of the heart and travels through arteries which gradually divide into capillaries. In the capillaries, food and oxygen are released to the body cells, and carbon dioxide and other waste products are returned to the bloodstream.The blood then travels in veins back to the right side of the heart, and the whole process begins again.

 

FACTOIDS: The body of an adult contains over 60,000 miles of blood

vessels! An adult's heart pumps nearly 4000 gallons of blood each

day! Your heart beats some 30 million times a year! The average three-year-old has two pints of blood in their

body; the average adult at least five times more!

A "heartbeat" is really the sound of the valves in the heart closing as they push blood through its chambers.

Respiratory System

Respiration is carried on by the expansion and contraction of the lungs; the process and the rate at which it proceeds are controlled by a nervous center in the brain.In the lungs, oxygen enters tiny capillaries, where it combines with hemoglobin in the red blood cells and is carried to the tissues. Simultaneously, carbon dioxide, which entered the blood in its passages through the tissues, passes through capillaries into the air contained within the lungs. Inhaling draws into the lungs air that is higher in oxygen and lower in carbon dioxide; exhaling forces from the lungs air that is high in carbon dioxide and low in oxygen. Changes in the size and gross capacity of the chest are controlled by contractions of the diaphragm and of the intercostals, muscles between the ribs.There is a close correlation between heart rate and breathing rate, both at rest and during activity such as everyday life or exercise when there is a higher demand of oxygen and energy.

Cardio-respiratory CapacityCardio-respiratory or aerobic fitness refers to the ability of the heart-lung system to deliver O2 to and remove CO2 from the working muscle during prolonged exercise activities.  The greater this ability, the higher the cardio-respiratory fitness level.  A low level of cardio-respiratory fitness is directly related to lack of exercise.  A regular exercise program leads to adaptive changes in the system to yield a higher cardio-respiratory fitness level.  Regular exercise is a significant factor in reducing the severity of cardiovascular disease.  To obtain an adaptive response of the cardio-respiratory system, demands must be made on the system that exceed those normally encountered.

Most experts recommend consideration of four factors:

* Frequency of Exercise - 3 times per week is the minimum required for improvement. 4 to 6 times per week will provide greater improvement.

* Duration of each Exercise Session - is the amount of time during each exercise session that the appropriate intensity is continuously maintained. Minimum is 20 minutes per exercise session. Duration and intensity are dependent upon each other in order to achieve improvement.  Duration needs to be increased if lower end intensity levels are chosen within the appropriate range.

* Intensity of the Exercise - is the degree of difficulty. Intensity is the most critical component of the exercise prescription.  A number of methods have been developed to determine the appropriate intensity level. Two of these methods are discussed in adjoining articles - heart rate reserve method to calculate target heart rate range and the rate of perceived exertion. A third method is maximal oxygen consumption (VO2 max).

* The Type of Exercise - in order for exercise to provide for improvement of the cardiorespiratory system, it must involve large muscle groups, be rhythmical and continuous while providing an adequate but not too great intensity. It must also be enjoyable. Examples are walking/jogging, running, bicycling, swimming, rope skipping, aerobic movement to music, or cross country skiing.

There are a variety of methods measuring your effort during your aerobic workout. The Karvonen method of calculating your target heart rate or training zone is based on your maximal heart rate (MaxHR) and resting pulse (RHR) and considered relatively accurate. Easier calculated but less accurate is the method using only the age specific maximal heart rate. Other methods include the Borg Scale of Perceived Exertion. This method relies purely on your subjective feeling of how hard you think you are working. This is especially helpful when the other methods can’t be used, e.g., when the exerciser has a condition that affects heart rate, e.g., takes certain medication or fights a disease causing agent. With a little bit of practice it is surprising how much this scale can correlate with the actual HR computed using one of the other methods.To determine your target training zone with HRR, do this:Take your resting pulse three mornings in a row, just after waking up, before sitting up or standing up. Add all of them together, and divide by 3, to get the average.Let's say your average is 60 beats per minute.The formula for the Karvonen method is:(220) - (your age) = MaxHR(MaxHR) - (resting heart rate) = HRR(HRR) x (60% to 80%) = training range %(training range %) + (resting heart rate) = (your target training zone)so,220 - 35 = 185 (MaxHR)185 - 60 = 125 (HRR)125 x .6 = 75 (60% training percentage)125 x .8 = 100 (80% training percentage)

75 + 60 = 135 (target training zone, in beats per minute)100 + 60 = 160 (target training zone, in beats per minute)

So, your target training zone, in beats per minute is 135 to 160. Of course, heart rate slows down immediately after cessation of exercise, sto get a 15 second target simply divide each number by 4. That would be 34 to 40 beats over 15 seconds. When counting beats, start with the first beat as zero: ie. 0-1-2-3-4....

the Borg scale of perceived exertion is another way of determining how hard you are working. 

Using your own subjective Rate of Perceived Exertion (RPE) on a scale of 6-20 or a scale of 0-10, you determine how hard you *feel* you are working.   

Original Scale Revised Scale6  0 - Nothing at all7- Very, very light 0.5 - Very, very weak8 1 - Very weak9 - Very light 2 - Weak10 3 - Moderate11 - Fairly light  4 - Somewhat strong12  5 - Strong13 - Somewhat hard 614  7 - Very strong15 - Hard  816 9 - Very, very strong17 - Very hard  10 - * Maximal18 -19 - Very, very hard -20  -* Maximal  -

The talk test is another good way of establishing how hard you are working, if you find it difficult to say a few words, you are probably working out anerobically. 

For a good indication of aerobic exercise, you should be able to say a few words, catch your breath, and then carry on talking. 

Aerobic Fitness Cardiorespiratory fitness, endurance fitness or aerobic fitness refers to the ability of the heart-lung system to deliver oxygen to and remove carbon dioxide from the working muscle during prolonged exercise activities. The greater this ability, the higher the cardiorespiratory fitness level or cardiovascular endurance level. A low level of cardiorespiratory fitness is directly related to lack of exercise. A regular exercise program leads to adaptive changes in the system to yield a higher cardiorespiratory fitness level. Regular exercise is a significant factor in reducing the severity of cardiovascular disease. To obtain an adaptive response of the cardio-respiratory system, demands must be made on the system that exceed those normally encountered. Considerable research has been done to determine the demand that must be placed on the cardiorespiratory system to

result in adaptive changes for improved aerobic fitness.

Four factors must be considered:

  (1) Frequency of Exercise - 3 times per week is the minimum required for improvement.            4 to 6 times per week will provide greater improvement.

  (2) Duration of each Exercise Session - is the amount of time during each exercise session that the appropriate intensity is continuously maintained. Minimum is 20 minutes per exercise session. Duration and intensity are dependent upon each other in order to achieve improvement.  Duration needs to be increased if lower end intensity levels are chosen within the appropriate range.

  (3) Intensity of the Exercise - is the degree of difficulty. Intensity is the most critical component of the exercise prescription.  A number of methods have been developed to determine the appropriate intensity level. Two of these methods are discussed in adjoining articles - heart rate reserve method to calculate target heart rate range and the rate of perceived exertion. A third method is maximal oxygen consumption (VO2 max).

  (4) The Type of Exercise - in order for exercise to provide for improvement of the cardiorespiratory system, it must involve large muscle groups, be rhythmical and continuous while providing an adequate but not too great intensity. It must also be enjoyable. Examples are walking/jogging, running, bicycling, swimming, rope skipping, aerobic movement to music, or cross country skiing.

Cardiorespiratory FitnessWhat is cardiorespiratory Fitness?Cardiorespiratory fitness refers to the body's ability to extract oxygen from the air, and deliver it to the muscles where it can be used to perform work/exercise. It is dependent upon the efficiency of the heart, the lungs, and the blood vessels.

In many ways cardiorespiratory fitness is the most important aspect of fitness because it improves the condition of the heart, the lungs, the blood vessels, and the blood. Almost all other organs rely on the cardiorespiratory system to deliver them nutrients and oxygen, and remove waste products. Therefore the health of the cardiorespiratory system directly affects the health of all other body systems and organs. In fact by conditioning the cardiorespiratory system, many ailments and diseases are relieved and or prevented. Furthermore regular aerobic exercise has been shown to substantially increase longevity and promote a healthy active old age.

The heart is in fact a muscle. Just like any other muscle if it is not exercised, it can become weak. And by the same token if a weak heart is exercised, it can become strong again. The lungs and blood vessels also can loose condition if not exercised, and regain their healthy condition when exercised. So even if you have not exercised for a long time, you can still benefit from regular exercise.

What are the benefits of improving cardiorespiratory Fitness?By improving cardiorespiratory fitness, you increase your ability to exercise at higher intensities for extended periods of time. For example, if you find that you are gasping for air and your heart is racing after climbing a few flights of stairs, then by regular aerobic exercise, you will find that such tasks come much more easily. Furthermore, aerobic conditioning exercise has many other benefits including having positive effects on the following:

Blood cholesterol levels

High blood pressure

Diabetes

Back pain

Obesity

Arthritis

Depression

Osteoporosis

Muscle pain, stiffness, cramps etc

Asthma

Digestive problems

and more...

It also strengthens the immune system, releives stress and tension and brings a great sense of well being! Regular aerobic exercise is probably the most important factor in general health and fitness.

What is a Calorie?A calorie is a unit of energy. We tend to associate calories with food, but they apply to anything containing energy. For example, a gallon (about 4 liters) of gasoline contains about 31,000,000 calories.

Specifically, a calorie is the amount of energy, or heat, it takes to raise the temperature of 1 gram of water 1 degree Celsius (1.8 degrees Fahrenheit). One calorie is equal to 4.184 joules, a common unit of energy used in the physical sciences.

Most of us think of calories in relation to food, as in "This can of soda has 200 calories." It turns out that the calories on a food package are actually kilocalories (1,000 calories = 1 kilocalorie). The word is sometimes capitalized to show the difference, but usually not. A food calorie contains 4,184 joules. A can of soda containing 200 food calories contains 200,000 regular calories, or 200 kilocalories. A gallon of gasoline contains 31,000 kilocalories.

The same applies to exercise -- when a fitness chart says you burn about 100 calories for every mile you jog, it means 100 kilocalories. For the duration of this article, when we say "calorie," we mean "kilocalorie."

What Calories DoHuman beings need energy to survive -- to breathe, move, pump blood -- and they acquire this energy from food.

The ultimate source of our energy resides in the food that we eat. The energy values of the various foodstuffs are known since the beginning of the 20th century: When 1.0-g of carbohydrate was oxidized to CO2 and H2O in a bomb calorimeter 4.1 kcal was released. Values for 1.0-g fat or 1.0-g protein were 9.1 or 4.1 kcal, respectively. Similarly, the calorie values of various substances in the body were determined and the next job was to find the chemical substance that directly provides the energy for muscle work.

The number of calories in a food is a measure of how much potential energy that food possesses. A gram of carbohydrates has 4 calories, a gram of protein has 4 calories, and a gram of fat has 9 calories. Foods are a compilation of these three building blocks. So if you know how many carbohydrates, fats and proteins are in any given food, you know how many calories, or how much energy, that food contains.

If we look at the nutritional label on the back of a packet of maple-and-brown-sugar oatmeal, we find that it has 160 calories. This means that if we were to pour this oatmeal into a dish, set the oatmeal on fire and get it to burn completely (which is actually pretty tricky), the reaction would produce 160 kilocalories (remember: food calories are kilocalories) -- enough energy to raise the temperature of 160 kilograms of water 1 degree Celsius. If we look closer at the nutritional label, we see that our oatmeal has 2 grams of fat, 4 grams of protein and 32 grams of carbohydrates, producing a total of 162 calories (apparently, food manufacturers like to round down). Of these 162 calories, 18 come from fat (9 cal x 2 g), 16 come from protein (4 cal x 4 g) and 128 come from carbohydrates (4 cal x 32 g).

Our bodies "burn" the calories in the oatmeal through metabolic processes, by which enzymes break the carbohydrates into glucose and other sugars, the fats into glycerol and fatty acids and the proteins into amino acids (see How Food Works for details). These molecules are then transported through the bloodstream to the cells, where they are either absorbed for immediate use or sent on to the final stage of metabolism in which they are reacted with oxygen to release their stored energy.

Click here for a simplified diagram of these metabolic processes.

BMRJust how many calories do our cells need to function well? The number is different for every person. You may notice on the nutritional labels of the foods you buy that the "percent daily values" are based on a 2,000 calorie diet -- 2,000 calories is a rough average of what a person needs to eat in a day, but your body might need more or less than 2,000 calories. Height, weight, gender, age and activity level all affect your caloric needs. There are three main factors involved in calculating how many calories your body needs per day:

Basal metabolic rate Physical activity Thermic effect of food

Your basal metabolic rate (BMR) is the amount of energy your body needs to function at rest. This accounts for about 60 to 70 percent of calories burned in a day and includes the energy required to keep the heart beating, the lungs breathing, the kidneys functioning and the body temperature stabilized. In general, men have a higher BMR than women. One of the most accurate methods of estimating your basal metabolic rate is the Harris-Benedict formula:

Adult male: 66 + (6.3 x body weight in lbs.) + (12.9 x height in inches) - (6.8 x age in years) Adult female: 655 + (4.3 x weight in lbs.) + (4.7 x height in inches) - (4.7 x age in years)

(Note: The first number in the equation for females is, in fact, 655. Strange but true.)

Your Caloric NeedsAs you now know, there are three main factors involved in calculating how many calories your body needs per day: your BMR, physical activity and the thermic effect of food.

Caloric Breakdown

1 g Carbohydrates: 4 calories 1 g Protein: 4 calories 1 g Fat: 9 calories

The second factor in the equation, physical activity, consumes the next highest number of calories. Physical activity includes everything from making your bed to jogging. Walking, lifting, bending, and just generally moving around burns calories, but the number of calories you burn in any given activity depends on your body weight. Click here for a great table listing the calories expended in various physical activities and for various weights.

The thermic effect of food is the final addition to the number of calories your body burns. This is the amount of energy your body uses to digest the food you eat -- it takes energy to break food down to its basic elements in order to be used by the body. To calculate the number of calories you expend in this process, multiply the total number of calories you eat in a day by 0.10, or 10 percent. If you need some help determining how many calories you eat in a day, check out these sites:

USDA National Nutrient Database Food Data Mike's Calorie And Fat Gram Chart

The total number of calories a body needs in a day is the sum of these three calculations. If you only want a rough estimate of your daily caloric needs, you can skip the calculations and click here.

StressMany people who feel tired or stressed use these feelings as anexcuse to skip their workout. This is understandable. Exercise takes quite a bit of energy and time, and when these are in short supply, it’s easy to rationalize skipping a workout.Psychologists who study health behaviour have found that when people are feeling stressed, the need to reduce stress becomes a top priority. The need to feel better now overrides the drive to do something that may lead to future benefits. In other words, if you feel bad and you think skipping your workout will make you feel better, you will probably skip your workout. The same sort of thinking goes for diets and addictions. If you think eating a big slice of chocolate cake will relieve the stress you are feeling right now, you are likely to eat it.. Stress is the most common reason people resume an addiction they had given up, such as smoking or drinking.Why not use exercise as a way to reduce stress and fatigue? If you can discover that exercise helps yuou feel good, this will not only help you stick to your exercise programme, but you’ll enjoy yourself in the meantime! You will also reap the numerous short and long-term physical and emotional health benefits that come with regular physical activity. And, if you freel less stressed, you will be better able to stick to your other healthful lifestyle resolutions, such as eating well or quitting smoking.

Talk yourself into exercise!Every time you exercise, notice how exercise helps you feel better. If you don’;t really enjoy the exercise itself (let’s admit it, many peole don’t !) at least notice how you feel better afterward. Many people report feeling less angry, irritabele, anxious or depressed. Perhaphs you also notice improved muscle strength or more stamina. Maybe you have better balance or muscle tone.

Once you believe exercise makes you feel better, remind yourself of this fact frequently. When you find you are talking yourself out of exercise, talk yourself into exercise instead!

Exercise, activity that results in contraction of skeletal muscle. The term is usually used in reference to any activity that promotes physical fitness. Although muscle contraction is the common element of all forms of exercise, many other organs and systems are affected, for example, the heart and lungs. Many people also find that regular exercise enhances their sense of mental well-being along with their general physical health.

Today there is an increasing emphasis on preventive medicine, or maintaining health, partly as a result of the increasing costs of health care and our greater awareness of the effects of lifestyle on health and longevity. While public interest in exercise and fitness has increased during the past 20 to 30 years, according to the United States National Center for Health Statistics, in 1990 only 41 percent of adults 18 to 64 years of age reported that they exercised regularly, and only 32 percent of those over 65 years of age reported regular exercise or participation in physical sports. Over one-quarter of Americans (three-quarters by some standards) are significantly overweight and are at risk for a wide variety of health problems.

II PHYSIOLOGY OF EXERCISE

Contraction of skeletal muscles, the muscles under conscious control, is the primary physiological event during exercise. Because skeletal muscles can actively contract, but are not designed to actively lengthen, they are arranged as opposing pairs. As one muscle shortens, another is stretched. An example of such a pair of muscles can be observed in the upper arm, where the biceps and triceps have opposite actions. To flex the arm at the elbow, the biceps contract, while the triceps stretch. To extend the forearm, the triceps contract, while the biceps lengthen.

At the molecular level, muscle contraction occurs when large proteins called actin and myosin slide together to shorten muscle fibers. The energy for contraction and relaxation of skeletal muscle is provided by a molecule called adenosine triphosphate (ATP). ATP is a high-energy molecule formed during the breakdown of glucose (a kind of sugar) or fats. Glucose can be stored in muscle as glycogen, and enters exercising muscle from the blood.

The metabolism of glycogen or glucose to provide energy for exercise occurs in one of two ways, depending on the presence of available oxygen to the muscle, which in turn depends on the type of exercise being performed. If oxygen is not available (anaerobic activity), glycogen or glucose will be broken down by the anaerobic pathway (glycolysis). If oxygen is available (aerobic activity), it will be metabolized by the aerobic pathway (known as the Citric Acid Cycle). When oxygen is readily available, glucose reacts completely with the oxygen to produce water and carbon dioxide. A portion of the energy released from one molecule of glucose is utilized to produce ATP.

A Anaerobic and Aerobic Exercise

During anaerobic metabolism, the breakdown of glucose stops at an early point, producing lactic acid and two molecules of ATP. This anaerobic metabolism produces a so-called oxygen debt, which is repaid later when oxygen becomes available. When a skeletal muscle is heavily worked, the acute soreness that results is due partly to a buildup of lactic acid. The presence of lactic acid can also be felt during exercise as a burning sensation in the muscles.

Anaerobic exercise involves heavy work by a limited number of muscles, for example during weight lifting. These types of activities are maintained only for short intervals, and the supply of oxygen is insufficient for aerobic metabolism, resulting in a substantial oxygen debt and anaerobic metabolism within those muscles. Another example is sprinting, in which the exercise is high in intensity but short in duration, resulting in substantial oxygen debt. Weight lifting and other types of anaerobic exercise increase strength and muscle mass, but are of limited benefit to cardiovascular health.

Unlike anaerobic exercise, aerobic exercise uses oxygen to keep large muscle groups moving continuously at an intensity that can be maintained for at least 20 minutes. Aerobic exercise uses several major muscle groups throughout the body, resulting in greater demands on the cardiovascular and respiratory systems to supply oxygen to the working muscles. Aerobic exercise includes walking, jogging, and swimming, and is the form recommended for reducing the risk of heart disease and increasing endurance.

IV HEART, RESPIRATION, AND EXERCISE

Although skeletal-muscle contraction is a main feature of exercise, many other systems in the body are activated to support this process. The heart pumps increased volumes of blood to supply oxygen and nutrients and remove carbon dioxide and metabolic wastes; the respiratory system handles an increased workload, exchanging oxygen and carbon dioxide between the blood and the atmosphere. The nervous system and various hormones have important roles as well, integrating the body's response to exercise and regulating the metabolic changes that occur in muscle and other tissues.

Another critical role of the cardiovascular system and respiratory system during exercise is to get rid of the heat produced by increased metabolism. During exercise, increased blood flow to the skin results in direct transfer of heat to the environment as well as loss of heat during evaporation of sweat. Substantial heat is also transferred to the atmosphere in exhaled air during breathing.

The effects of exercise on the heart and circulation can vary considerably with intensity of exercise and with physical fitness. Assessment of a person's physical fitness often includes measurement of aerobic capacity in the form of maximum oxygen consumption, or VO2 maximum, during aerobic exercise. Oxygen consumption of like-sized fit and unfit individuals will be approximately the same at rest or at a given level of exercise, for example, walking on a treadmill. But the more fit person will be able to achieve a greater maximal oxygen consumption due to the training effect that takes place with regular aerobic exercise. As a person engages in regular aerobic exercise, the heart, lungs, and muscles all become more efficient at using oxygen. The heart pumps more blood with each stroke, the lung capacity of each inhalation increases, and the muscle fibers extract more oxygen from the blood. The training effect on the heart is quite obvious when heart rates are compared between long-distance runners and sedentary individuals. The athlete will have a lower heart rate at rest (perhaps as low as 50 beats per minute) and during light jogging, for example, than the nonathlete (who might have a resting rate of 80). During light jogging, the untrained person will experience a large increase in heart rate, while the athlete's heart rate will not rise nearly as much.

V BENEFITS OF EXERCISE

The benefits of exercise are far-reaching. Clinical and epidemiological studies have demonstrated that regular aerobic exercise reduces the risk of death due to heart disease and stroke, aids in reducing weight, helps prevent diabetes mellitus, strengthens bones, and enhances immune function. The psychological benefits are also broad, and most studies suggest a positive relationship between physical fitness and mental achievement.

The relationship between regular aerobic exercise and cardiovascular health and longevity is well established. Regular exercise leads to a reduction in the risk of coronary heart disease, in which fatty deposits (plaque) form in blood vessels supplying the muscular wall of the heart, compromising oxygen delivery to the heart muscle. In addition, with regular exercise the efficiency of the heart during exercise is increased.

Many people exercise to lose weight. A calorie is a unit that measures the energy content of foods and the energy expenditure by the body. When the daily calorie intake from food is the same as calories expended from exercise, weight remains the same. The number of calories burned during exercise varies greatly with the type of physical activity, but the key to successful weight reduction is to exercise regularly, without increasing food intake proportionally. For example, walking one hour per day may utilize only 300 calories of energy per day, a small fraction of an individual's daily caloric intake. But over a period of time, if food consumption is simultaneously reduced or remains the same, significant weight loss will result. One sound approach to reducing calories is to eat healthier foods that contain more fiber and less fat, and therefore fewer calories. This type of diet has also been proven healthier for the heart and blood vessels.

One area of controversy has been how much exercise is enough to improve general health, reduce the risk of heart disease, and increase longevity. Meaningful studies on this topic are very difficult to perform because they require large populations of subjects and many years of data collection, and because poor health sometimes results in limitations to physical activity. Despite these difficulties, it is clear that regular exercise, along with a generally healthy lifestyle, is beneficial. People who have sedentary lifestyles make up half the population of industrialized societies, and this group has the most to gain by exercising. One recent U.S. National Institutes of Health (NIH) panel suggested that as little as 30 minutes every day of purposeful, moderately strenuous physical activity—for example, rapid walking or lawn mowing—is sufficient to lower the risk of heart disease. There is no conclusive evidence to prove that an especially rigorous exercise routine, such as running many miles per day, as opposed to walking or jogging daily, will add years to a person's life.

VI GETTING IN SHAPE

Physical fitness is often defined in terms of four measurements: cardiovascular-respiratory function, body composition (the proportion of lean body mass in comparison to fat), flexibility, and muscular endurance and strength. Exercise is characterized in terms of four variables as well: frequency, intensity, duration, and mode. In planning an exercise program, it is important to take into account one's personal fitness objectives and the exercise regimen that will best meet those objectives. Age and existing health

conditions should also be considered. Individuals over the age of 40 or who suffer from serious health problems or physical limitations should first consult a physician for recommendations about the best exercise program to adopt.

A Fitness Goals

If overall fitness or prevention of heart disease is a primary goal, 20 to 30 minutes of moderate-intensity, daily aerobic exercise—such as walking, jogging, swimming, or dance aerobics—should be considered. In general, begin with shorter exercise sessions and gradually work up to 20 to 30 minutes. In addition to reducing risk of heart disease, such an aerobic-exercise program will also help in weight reduction and altering body composition, and in enhancing flexibility.

If improving muscle strength is the primary consideration, regular, high-intensity workouts with weights are more appropriate. Studies have shown that even older people can benefit greatly from a weight-lifting workout. In particular, bone density, often a concern in the elderly, is increased, muscle atrophy (decrease) is prevented, and general strength and coordination are improved by this type of exercise. A structured, supervised weight program after consultation with a physician is recommended.

Stretching exercises, including yoga, will enhance flexibility. In planning an exercise program, be sure to include stretching exercises and warm-up and cooldown periods to prevent muscle pulls and other injuries.

B Exercise Intensity

If an aerobic program is adopted, in addition to duration (at least 20 to 30 minutes) and frequency (daily or several times a week), intensity of the exercise should also be considered. The intensity of the aerobic exercise can be determined by evaluating the heart rate attained during exercise. The maximum heart rate (beats per minute) for an individual is approximately 220 minus age. To improve aerobic capacity (VO2 maximum), exercise should be performed at an intensity that produces a heart rate of at least 70 percent of this maximum. For a 20-year-old, for example, the maximum heart rate is 220 - 20, or 200. The heart rate should rise to at least 140 (70 percent of 200). You can determine your heart rate by placing two fingers over the radial artery in the wrist or the carotid artery of the neck. By keeping an occasional record of heart rate responses to a standard exercise (for example, jogging at a rate of 1 mile per ten minutes), it is possible to track your fitness progress; over a period of several weeks, the same exercise will produce a lower heart rate. Similarly, the intensity of exercise (such as the speed of jogging) required to produce a given rise in heart rate will increase.

The most important aspect of getting in shape is to make exercise an integral part of one's lifestyle. Exercising to stay as physically fit and healthy as possible should be a lifelong commitment, and is especially important to people who perform little physical work in their day-to-day lives.

Why do we eat? Energy, Building Blocks and Essential Nutrients

A healthy diet supplies energy (fuel for the cells in the form of glucose) , building blocks and essential nutrients. Our cells individually work to make us function. When our heart beats, lungs breathe, or muscles contract, it is individual cells that do all that. They fuel up not on pizza or cheeseburgers, but rather use only the simplest molecules, such as glucose, amino acids or fatty acids. These simple molecules are called building blocks.

We cannot directly use a pizza in our body -- it just does not serve a function in it's pizza form. But that pizza can be broken down . The protein in the meat, cheese and crust is broken down in amino acids. The fats in the crust, meat and cheese are broken down to glycerol and fatty acids. The carbohydrates in the crust, and the vegetables are broken down into simple sugars such as glucose. The body then uses the glucose, amino acids, fatty acids and glycerol to build the molecules that we do need. Given a source of organic carbon (such as sugar) and organic nitrogen (such as amino acids from digestion of proteins), an animal can fabricate a great variety of organic molecules by using enzymes to rearrange the molecular skeletons of precursors. There are some things that the body needs, however, but cannot make. These are called essential nutrients.

Essential nutrients are amino acids,fatty acids, vitamins and minerals. We can make 11 amino acids, but must ingest other 9 (we need 20 amino acids in total). Humans can manufacture some, but not all fatty acids. We do make some of the vitamins -- organic molecules-- we need (actually bacteria in our gut make some), but we have to eat the rest. Finally, we need minerals in very small quantities, but we obviously cannot make elements. So, we now know we need to eat foods that supply carbohydrates, proteins, fats, vitamins and minerals. But where do they come from?

Nutrition Labels: Understanding and using them

The nutritional information given on a food label is based on a serving size. It relates this serving size to the % daily value. The daily value for calories depends on one's sex and age, but the average is considered to be 2000.

When you add up all that you have eaten on a given day, the proportions of the three macromolecules (carbs, proteins and fats) should be a certain percentage of 2000 kcalories:

65 grams should come from fat (30% of the kcalories); 20 grams of these 65 grams from saturated fat (10% of the kcalories);

300 grams should come from carbohydrates (60% fo kcalories);

25 grams of fiber (no kcalories);

50 grams should come from protein (10% of kcalories);

fat yields 9 kcalories/gram

carbohydrates yield 4 kcalories/gram

proteins yield 4 kcalories/gram

9 kcalories/gram * 65 grams = 585 calories from fat

4 kcalories/gram * 300 grams = 1200 calories from carbohydrates

4 kcalories/gram * 50 grams = 200 calories from protein

Food Pyramid

We require three types of macromolecules (macronutrients) to supply energy and building blocks: carbohydrates, proteins and fats. We also require minerals and vitamins.

More than half of our diet should come from bread, cereal, rice and pasta, preferably whole-grained (more fiber, vitamins and minerals). We should have 6-11 servings of these foods each day.

We should have 2-4 servings of fruits and 3-5 servings of vegetables. Fruits and vegetables are a great source of fiber, vitamins and minerals.

We need 2-3 servings of dairy products and meats.

Fats and sugars should be minimized.

Carbohydrates -- sugar and starch. Principle product of carbohydrate breakdown is glucose. Glucose not immediately needed for energy is stored as glycogen in the liver and muscles. When we are eating carbs, we are eating from the bottom two levels of the food pyramid -- grains, bread, cereal, pasta, vegetables and fruit. Sixty percent of our calories each day should come from carbohydrates. Complex carbohydrates (white flour products) are a good source. They lack fiber, however. Most fiber in complex carbs has been removed. Fiber is the casing around the grain. Supercomplex carbs are richer in fiber, thus a healthier source for both carbohydrates and fiber. Eat whole-grain products, such as oatmeal, barley, bulgur wheat, wild and brown rice. They are better than just complex carbs.

In 1996, Americans ate 152 pounds of sweeteners in products found at the very top of the pyramid -- called fats and sweets. Although a product label must include all ingredients in the order of greatest to least amount, the large amount of sugar is often hidden because several kinds of sugar are often used in a given product. Some of them sound quite healthy: high fructose corn syrup, dextrose, corn syrup, honey, fructose, and finally sugar. Be aware, they are all just sugar!

Proteins give cells their structure and are the components of enzymes, hormones, neurotransmitters, muscles and more. They are made up of amino acids. We need proteins in our diet because we break them down and use the amino acids to build various proteins that our bodies need -- hormone, enzyme, muscle fiber. We can use protein as a source of energy, but this is inefficient. Usually the body does not use proteins as an energy source because proteins are too valuable for muscle, enzymes, antibodies, hair, cartilage, hormones, etc. The body can break proteins down during starvation, after all available carbohydrates and fats have been used, by converting amino acids to glucose in the liver. The third level of the food pyramid supplies our protein needs: 10%of our calories should come from protein each day. Proteins are described as either complete or incomplete.

Complete proteins supply all 20 amino acids. We can make 11 of these amino acids but the other nine are considered essential, which means that we have to eat them because we cannot make them. Animal proteins such as meat, eggs, milk and cheese supply all 20 amino acids. Plant proteins do not. So, a vegetarian diet has to be carefully planned to include a mixture of corn, beans, rice and grains.

A vegetarian diet can be healthier than a diet that includes red meat and dairy products, as these contain saturated fats. However, a vegetarian diet is not recommeded for young children because it is so hard to get all the essential amino acids. Eating meat supplies all 20 amino acids. No plant protein can supply all 20 amino acids, except soy and quinoa. So, the diet must include a combination of plant proteins. It is no coincidence that many third world diets include corn and beans. Corn and beans together, supply all 20 amino acids. Amino acids are not stored like sugars are. The liver can hold on to them for a while, but you must eat all 20 every day in order to keep the body running smoothly. A vegetarian diet, thus, takes a bit more tought and preparation than the diet of carnivores.

Lipids -- fats, oils, cholesterol-- are another source of stored energy. They should make up no more than 30% of our diet and should include mono- and poly- unsaturated fats instead of saturated fats! Remember that some fats are essential because we cannot make them in our bodies. We must eat fat to get the essential fatty acids. We need fats to make up new cells. The downside of fat is that it causes cardiovascular diseas, by clogging the arteries. Fats are found in many of the foods we eat -- usually the foods that taste best. They are also found at the top of the food pyramid, and should be used with restraint.

Saturated fats are those found in meats, candies, dairy products and pastries, and are associated with cardiovascular disease because they raise the levels of LDL (or popularly known as "the bad cholesterol") in our blood. Polyunsaturated fats like canola oil lower the risk of cardiovascular disease, but increase the risk of cancer. What fats are then good for you? Olive and peanut oils are monosaturated and seem to be best for us because they do not cause heart disease or cancer.

Hydrogenated vegetable oils sounds like a good thing but it is not! They are vegetable, but hydrogenated means that they have been made saturated and thus contain trans fatty acids.

Cholesterol is made by the body and is necessary because it is the precursor of steroid hormones such as estrogen, progesterone, and testosterone. It is also found in plasma membranes, and helps keep them fluid at lower temperatures.

The bottom line is that a healthy diet should come from a variety of sources. Furthermore, one should always remember that any food is healthy food when consumed in moderation! Remember the food pyramid and stick to its model and you

will be eating healthy. Add to that regular exercise -- half an hour of brisk walking daily will do-- and you will live a healthy and happy life! It is not as hard as many of us may have thought, is it?

Feet – The Hands that Touch the EarthThe Spine Health & Fitness: Body Systems

Bones / SkeletonSkeletal MusclesHeart & LungsMetabolism: Energy Systems & NutritionThe Senses (Balance)

Health & Fitness: Exercise

Take Home Exam (link to a separate page)

separate pages for:

Base: DOMS, FeetCore: Spine, AbsBody Systems: Skeletal, Muscular

Cardio-PulmonaryEnergy Systems: Metabolism

NutritionFitness: Balance (The Senses)

Exercise (cardio, conditioning, flexibility) how often, structure,

add:chapter about scapula position, movements, stabilization