a course on cfd

8/7/2019 A Course on CFD

http://slidepdf.com/reader/full/a-course-on-cfd 1/22

A Course on CFD & Rapid Product Development/Reverse Engineering

This Program will begin with an overview to CFD, RPD&RM. This will be followed by thedetailed presentations on various topics of the three groups of technologies constituting

RPD&RM. These presentations will be made by experts from academia and industry. Apart from

the basic concepts, these will include demonstrations and case studies as well.

Program Co-ordinators: VELOZETA, National Institute of Technology Calicut (NIT-C) Indian Institute of Technology Bombay (IIT-B)

Targeted Audience Graduate Engineers or experienced diploma engineers.

Course Duration: July 15th - August 14th, 2008

Last Date for Registration: June 30th, 2008

Fees: INR 45,000/-

Contact: 09947824645 Email: [email protected] , [email protected]

Detailed Course Content

The topics that will be covered are: y Overview to Rapid Product Development y Introduction to Computational Fluid Dynamics using FLUENT as

an Engineering Tooly Geometric Modeling: Wire-frame, surface and solid representations;

need for multiple solid representations; STL formaty V irtual and Augmented Reality: Stereo-vision; tracking-based

interaction; multi-modal perception; applications and case studiesy Finite Element Analysis: Principle; applications and case studiesy Reverse Engineering: Principle; legal and ethical issues; various

contact and non-contact methods of capturing a physical object;construction of the 3D models; applications and case studies

y Rapid Prototyping: Principle; popular RP processes like FusedDeposition Modeling (FDM), 3D Printing (3DP), Stereo-Lithography (SLA) and Selective Laser Sintering (SLS); applications/benefits andlimitations of RP

y Rapid Tooling: Direct metallic tool making using processes like SLS,3DP and Laminated Tooling; Indirect metallic tool making using



processes like Spray Metal Tooling and 3D KelTool; Benefits of conformal cooling ducts and their manufacture

y Overview to Rapid Manufacturing: Definition; Roadmapy Rapid Manufacturing of Non-metallic Objects: Silicon Rubber

Molding; Epoxy Tooling y Rapid Manufacturing of Metallic Objects through Layered

Manufacturing: Comparison of powder-bed and deposition methodsfor building metallic objects; Comparison of energy sources such aslaser, electron beam and electric arc; Powder-bed technologies likeSLS, 3DP and Arcam; Deposition technologies like Laser AdditiveManufacturing (LAM), Laser-Engineered Net Shaping (LENS),Shape Deposition Manufacturing (SDM) and Arc Hybrid Layered

Manufacturing (ArcHLM)y Laminated Manufacturing: Issues in the joining of laminates; case

studiesy High Speed Machining in Rapid Manufacturing: Scientific definition;

enabling technologies, viz., cutting tools, machine tools and CAMpackages; benefits

y Rapid Casting: RM of metallic objects through Material Translation,i.e., Investment Casting; Segmented Object Manufacturing (SOM)

y Design and Manufacture Using Functionally Gradient Materialsy Aerospace Applications of Rapid Manufacturing y Biomedical Applications of Rapid Manufacturing y Micro-Manufacturing y Concurrent Engineering and Design for X y Product Lifecycle Management

y Rational and Irrational Hypertrophyy Metabolic processes within the cell require ATP to ³fuel´ them

(ATP is the body¶s primary fuel source for all of its energy). If

enough ATP isn¶t present then a host of cellular processes slowdown (including protein synthesis), resulting in the operations of

the cell being compromised. This means, among other things,



slower removal of waste products, slower recovery from training

and slower or less protein synthesis. Research done in the former Soviet Union by Zalessky and Burkhanov has shown that if the

contractile components of the cell continue to grow (sarcomere

hypertrophy) without a concurrent increase in the energy supplyingsystems of the cell (i.e. mitochondria, etc. ± sarcoplasmic

hypertrophy) then such a situation will develop.

y Essentially, the contractile machinery of the cell has growntoo large for the energy systems to support it. In addition,

fellow Soviet researchers, Nikituk and Samoilov have

demonstrated that such a condition can be brought about

through poorly planned resistance training.

y Once such a situation is created, the full potential strength of themuscle cannot be exerted because the cell cannot produce and

utilize enough momentary ATP to cycle actin-myosin cross-

bridges sufficiently. Likewise, when hypertrophy and

strengthening is stimulated, growth cannot be supported becausethe cell lacks the energy systems necessary to support the synthesis

and maintenance of new proteins (muscle protein is constantly

being broken down and rebuilt ± a process of µmaintenance¶). InBodybuilder¶s terms, you hit a plateau. Because such a condition is

unproductive from an adaptive standpoint, it is called irrational

hypertrophy.

y The defining characteristic of this kind of growth is cells that

contain significantly larger mitochondria than in the

untrained state, but fewer of them per myofibril. The net

result is an ATP shortage in the cell.

y On The Other Hand

y

If training results in proportionate vascular improvements within

the cell (mitochondrial density increases ± the total number of mitochondria also increases as the existing mitochondria getbigger), such a plateau will not be encountered and training-

invoked hypertrophy can proceed. This is called rational

hypertrophy, for obvious reasons.



y As this article isn¶t intended to get into the details of training

procedures, I¶m going to leave this subject by saying that for continued progress with regard to increased muscle mass

and/or strength-endurance, sarcoplasmic hypertrophy is,

indeed, necessary and must be trained for.y ³But Why Aren¶t Olympic Lifters Bigger Than

Bodybuilders?´

y It wouldn¶t be right not to address the fact, though, that trainingwith weights ~90% of your 1RM and above seems to favor the

development of strength more so than muscular size. But, in light

of the information presented in Part I of this series, how is that

possible? It is theorized that when using loads of ~90% of 1RM

and above muscular failure may occur because of signalingproblems at the neuromuscular junction, and that this occurs before

a significant growth stimulus has been delivered to the cells. In

addition, the total time that the muscle fibers are required to

produce force is shorter in low-rep sets than in higher-rep sets andthis may result in exhaustion of fewer muscle fibers and a lesser

growth stimulus.

y Simply put, a hard set of 8 reps may deliver more growthstimulus to the muscle cells than a hard set of 3 reps because

in a 3-rep set (or any low number of reps) failure may occur

before a significant growth stimulus has been achieved.

y Effect Of Higher Reps

y Additionally, when higher reps are performed substrates such as

phosphate and hydrogen ions build up in the muscles ± some

researchers theorize that the presence of these substrates may

further facilitate the muscle growth process (though this has notbeen confirmed). It is also widely believed that lifting heavy

weights (~90% of 1RM and above) effectively stimulates thenervous system to µimprove¶ its recruitment pattern, frequency andefficiency to produce limit strength, making you stronger without

actually increasing muscle size. These reasons are why

bodybuilders, as a group, have bigger muscles than Olympic lifters



± they typically train with longer-duration, higher-rep sets, which

is an effective method of producing hypertrophy.

y Olympic Lifters, on the other hand, typically train with short-

duration, low-rep sets, which is an effective method of

producing strength gains due to neural adaptations, butproduces little in the way of hypertrophy. Accordingly,

Olympic lifters, as a group, are much stronger than

bodybuilders, but not as heavily muscled.

y Other Important Factors

y It also needs to be pointed out that any type of repetitive weight

training (regardless of rep range) will result in the type IIB fibers

having endurance-type adaptations. This occurs most quickly and

profoundly at lighter loads (8-15 rep maximums) because, withthese loads, the type IIBs do not twitch with maximum frequency

and, therefore, adapt to twitch at lower frequencies for longer

periods. This adaptation improves the IIB fibers ability to produce

tension for longer periods of time, thus allowing them to be trainedin a fashion that produces substantial muscular damage and greater

growth stimulation. This gives the Bodybuilder¶s muscle more

potential for growth. Training in the 8-15 rep range (roughlyspeaking) also constitutes endurance training for IIB fibers,

causing them to adapt so that they have better endurance

characteristics (i.e. higher mitochondrial densities and greater abilities to sustain enzyme concentrations).

y In other words, sarcoplasmic hypertrophy. This increases the

IIB fibers¶ energy production capabilities, allowing for

further stimulation of sarcomeric hypertrophy and the

development and maintenance of muscle proteins.

y

My Point

y Don¶t do as others have, and use these observations to argue thatbigger muscles are not stronger muscles. As was eluded to above,muscles adapt very specifically to specific tasks. If you train using

three rep sets then they get good at doing three rep sets. If you train

using 8 rep sets then they get good at doing 8 rep sets. Moderate-

reps sets, however (such as 8-12 reps), stimulate more muscle



growth than low-rep sets (assuming of course, you are training

with sufficient intensity).

y Make no mistake about it though, your legs will be bigger

when you¶re squatting 405 for 8 than they were when you

were squatting 275 for 8. For the case of 3 rep sets, you maynot be much bigger when you¶re cleaning 315 for 3 than you

were when you were cleaning 185 for 3, but you will have a

much more efficient nervous system for the task.

y Take Home Lessons!

y y y y y y y If you want to grow bigger muscles you must train your muscles

against a resistance great enough to stimulate hypertrophy, but not

so great that you cannot continue the set long enough to stimulate

growth. Practically, that means you must select weights that allow

you to complete 6-12 reps (smaller muscle groups may respond



better to even higher reps). Most people will use between 70% and

85% of their 1-rep maximums to achieve this. Training in thisrange produces micro-trauma to the muscle fibers that results in

muscle growth (if proper rest and nutrition is supplied). If your

primary concern is increasing limit strength, then you should trainwith weights over 85% of your 1-rep maximum, and the sets (by

necessity) will be of 5 or less reps. If you want to avoid

hypertrophy as much as possible, while increasing strength asmuch as possible, then sets of 1-3 reps using weights of over 90%

of 1-rep max are indicated.

y Training in this range produces little micro-trauma, thus

stimulating little growth, but results in nervous system firing

pattern refinements that increase limit strength.y Size Factor

y In all cases, if you want to get stronger OR bigger, you MUST

train for strength. Getting stronger in the rep range that you¶re

using is the most fundamental sign of progress ± it is the rep rangethat determines whether the training effect will be strength or

muscle mass increases.

y If you are not getting stronger in your training rep range, thenyour training is not working. This fact cannot be ignored, it

cannot be argued around, and it cannot be refuted ± it is as

fundamental, and as simple, as that

Strong Science ± Research On The Ideal Rep Range & Sets To

Maximize Results

When it comes to the perfect training program, there are three key

variables for gaining strength and muscle mass: the number of sets per

bodypart, the number of reps completed per set and the frequency with

which each bodypart is trained.

Yet, if you were to ask the bodybuilding industry¶s biggest pros for their

numbers of sets, reps and training frequency, you¶d be surprised at how



much their answers would differ. This means that different training

schemes work better for some individuals than for others, which is oftena frustrating realization for aspiring bodybuilders seeking the best way

to train.

The Big Debate

This topic is debated in local gyms, college strength rooms and exercise

physiology laboratories. There are so many differing opinions that it

makes even the smartest exercise scientist¶s head spin. Searching

through scientific journals only turns up conclusions that vary from one

study to another. Most scientific studies have two major flaws. One

problem is that they often involve only a small group of subjects

(usually 10-20) who are supposed to represent the bodybuilding

majority. The other problem is that many weightlifting studies usebeginners as subjects. Even the least-educated bodybuilder knows that

beginners respond to training much differently than experienced

bodybuilders.

Researchers

Fortunately, scientists from Arizona State University in Mesa, Arizona,have published a study that could give us some solid answers. They

gathered data from 140 well-designed weightlifting studies and

compared the optimum number of reps and sets and the best trainingfrequency for inducing strength gains in both novice and trained

(defined as having lifted weights consistently for more than one year)

weightlifters. Then, the data was analyzed using a statistics method thatcalculated the optimal rep, set and frequency scheme for beginner and

advanced weightlifters (see ³Strong Results´ sidebar).

Intensity Rules

Intensity refers to the number of reps and the amount of weightemployed.



Beginners

The study concluded that beginners should start with a program of

higher reps and lighter weight. Those who have been lifting for less than

a year should use weights that allow 12-15 reps to be completed per set.Beginners make considerable strength gains by adaptations that occur

within the nervous system. Lifting weights teaches the nervous systemhow to fire signals to the muscles faster and more efficiently so that the

right muscle fibers are optimally recruited during a lift. Using more

repetitions allows the nervous system to get more practice, as it must

work to control each and every rep.

Advanced

For advanced trainers, heavier weight and lower reps produced the

greatest strength gains. If you¶ve been training for more than a year and

are interested in making strength gains, use weights that allow you tocomplete about six to eight reps per set. According to the concept of

progressive overload, as muscles adapt to repeated training, you must

challenge them with heavier weight.

Therefore, advanced trainers need to use poundages that are relativelyheavier than those a beginner would use.

Pump Up The Volume

Volume refers to the total number of sets performed for one bodypart

during a workout. If you do three sets of three exercises for chest, the

total volume is nine sets.

B

eginnersThe Arizona team discovered that beginners should complete only three

or four sets per bodypart for good strength results. In the study, optimal

results for beginners interested in gaining strength were achieved withthree sets of one exercise per bodypart.



When performing only one exercise per bodypart, we recommends that

it be a basic exercise, such as bench presses or incline bench presses for chest, barbell or dumbbell overhead presses for shoulders, barbell rows

or pulldowns for back, squats or leg presses for legs, close-grip bench

presses or skull-crushers for triceps and standing barbell or dumbbellcurls for biceps. Considering its lower volume of exercises, this workout

can be done as one full-body workout or split into two separate workouts

that train the entire body (quads, hams, chest and triceps one day, for example, and back, shoulders, biceps and calves the next).

Advanced

The volume of sets for advanced trainers is increased slightly but still

remains on the lower side. Researchers found that advanced trainers who

are concentrating on strength gains should perform only about four to sixsets per bodypart. For most people, that means three sets of two

exercises. The best option is to pick one basic exercise for each muscle

(as previously described for beginners) and one assistance exercise (onethat trains the muscle group in a similar manner to the basic exercise or

that trains the muscle group using a single-joint exercise).

Basic Exercises

For chest, do flat bench presses and incline dumbbell presses or dumbbell flyes. For shoulders, do barbell or dumbbell overhead presses

followed by upright rows or lateral raises. For back, do bent barbell rows

or pulldowns followed by one-arm dumbbell rows or seated cable rows.

A good leg workout would entail squats or leg presses followed by

lunges or leg extensions. For triceps training, perform close-grip benchpresses or skull-crushers followed by triceps pressdowns.

And for biceps, follow standing barbell or dumbbell curls with preacher

curls or incline dumbbell curls.

The best type of workout split is a 2 or 3 day training split

Again, progressive overload is behind the increase in the number of setsper bodypart for advanced trainers. As muscles adapt, increase the



amount of stress they receive. One way to do this is to increase the

number of sets performed. Of course, the increase only enhancesstrength to a degree. Scientists found that when more than six sets per

bodypart were performed, strength gains were not as significant as for

those who trained with four to six sets per bodypart.

Whats The Frequency?

Frequency refers to the number of times a bodypart should be trained

each week.

Beginners

As far as weekly training frequency goes, beginners should train eachmuscle group three times per week. (A beginner may choose to split his

bodypart training over two workouts, resulting in a six-day-a-week program that works each muscle group three times weekly.)

Weightlifting trains a beginner¶s nervous system, and by training more

frequently, the nervous system can adapt at a faster pace. To make sense

of this concept, consider when children learn to ride a bike. The more

often they practice, the faster they learn.

Advanced

On the other hand, advanced trainers should not train a bodypart more

than twice per week to optimize strength gains. Unlike beginners,advanced trainers¶ nervous systems have pretty much adapted by this

point. Their strength gains come mainly from adaptations in the muscle

fibers themselves. Because training with heavy weights and more totalsets causes more muscle damage than beginners would experience if

they used lighter weights and fewer sets (as suggested by this study),advanced lifters require more recovery time between workouts.

This allows the muscles to regenerate muscle protein and grow larger

and stronger.

Bottom Line



³Bodybuilders aren¶t as strong as Powerlifters´ argument. If strength was related to muscle mass,wouldn¶t Powerlifters be bigger than Bodybuilders?

The explanation is simple: Strong people usually have better mechanical advantages than weaker

people.

This includes more favorable joint lengths and connective tissue factors (including attachmentplacings and superior tendon and ligament strength). They may have more type II fibers than

others and/or a more efficient nervous system (which can be trained for). A muscle can betrained to get stronger but not bigger ± this depends on rep range, training volume and frequency.

However, if a muscle gets larger it must also get stronger in the rep range over which it wastrained. Likewise, if a muscle gets stronger in a rep range conducive to producing growth then

the muscle will also get larger.

It is a scientifically verified physiological fact that muscle size and strength are directly related.

Let¶s take a look at what happens to a muscle when you train it.

Segment from the Neuromuscular System series:

³Muscle biopsies of experienced bodybuilders have shown that it was the size of the individual

fibers within their muscles that was responsible for the abnormal muscle size and not the actualnumber of fibers present.´ Although there is some evidence that extreme conditions may result in

modest increases in fiber number (hyperplasia), the mechanism responsible for muscle sizegrowth is hypertrophy ± the increase in size of existing muscle fibers.

Another segment from the Neuromuscular System series:

³It is also worthy of note that contractile machinery comprises about 80% of muscle fiber volume. The rest of the volume is accounted for by tissue that supplies energy to the muscle or is

involved with the neural drive.´

This tells us that there are a couple of ways to increase muscle size.

1. Increase the volume of the tissue that supplies energy to the muscle or is involved with

the neural drive ± called sarcoplasmic hypertrophy.2. Increase the volume of contractile machinery ± called sarcomere hypertrophy.

Let¶s take a look at both routes.

Sarcoplasmic Hypertrophy

Increasing the volume of the tissue that supplies energy to the muscle or is involved with theneural drive: Intimately involved in the production of ATP are intracellular bodies called

µmitochondria¶. Muscle fibers will adapt to high volume (and higher rep) training sessions byincreasing the number of mitochondria in the cells. They will also increase the concentrations of



the enzymes involved in the oxidative phosphorylation and anaerobic glycolysis mechanisms of energy production and increase the volume of sarcoplasmic fluid inside the cell (including

glycogen) and also the fluid between the actual cells. This type of hypertrophy produces verylittle in the way of added limit strength but has profound effects on increasing strength-

endurance (the ability to do reps with a certain weight) because it dramatically increases the

muscles¶ ability to produce ATP. Adaptations of this sort are characteristic of Bodybuilders¶muscles.

It should also be obvious that as the volume of the tissue that supplies energy to the musclerepresents only around 20% of the total muscle cell volume in untrained individuals, this isn¶t

where the majority of growth potential lies.

Hypertrophy Factor

Sarcoplasmic hypertrophy of muscle cells does directly produce moderate increases in size. But

also, ATP is the source of energy for all muscular contraction ± type II fibers included. Wouldn¶t

having more of this in the muscle, and having the ability to produce greater intramuscular quantities at any one time, be an asset? The answer is, clearly, ³yes´. That¶s where a major portion of the importance of sarcoplasmic hypertrophy comes into Bodybuilding. As for

increasing the tissue that is involved with the neural drive, this would theoretically occur inresponse to the need for contracting cells with hypertrophied contractile machinery. Directly, it

would produce very little in the way of added size. In addition, there are other intracellular bodies whose growth and/or proliferation would fall under the category of sarcoplasmic

hypertrophy.

These would be organelles such as the ribosomes, which are involved in protein synthesis. As in

the case of neural drive machinery, in most cases they would increase in size or number only to

support sarcomere hypertrophy. They would have little direct impact on overall muscle size.

Sarcomere Hypertrophy

Increasing the volume of contractile machinery: The vast majority of the volume of each musclecell (~80%) is made up of contractile machinery. Therefore, therein lies the greatest potential for

increasing muscle cell size. Trained muscle responds by increasing the number of actin/myosinfilaments (sarcomeres) that it contains ± this is, primarily, what is responsible for the increased

strength and size. But before a muscle will grow like this it has to be µbroken down¶.

Let¶s take a look at both the µbreaking down¶ and µbuilding up¶ processes:

The Process Of Exercise-InducedMuscle Cell Damage

When a muscle fiber develops sufficient tension for sufficient time, increasing fatigue impairsthe actin/myosin cross-bridge cycling necessary for the contractile filaments to maintain force



production. This impaired cross-bridge cycling under load results in trauma to the contractilefilaments as some cross-bridges are subjected to tensions greater than they can structurally

support. Additionally, training leads to post-workout breaches in plasma membrane integrity thatallow calcium to leak into the muscle cells (there is much more calcium in the blood than in the

muscle cells). This intracellular increase in calcium levels activates enzymes called µcalpains¶

which remove pieces of the damaged contractile filaments (called µeasily releasablemyofilaments¶).

A protein called µubiquitin¶ (which is present in all muscle cells) binds to the removed pieces of filaments thus µidentifying¶ them for destructive purposes. At this time, neutrophils (a type of

granular white blood cell) are chemically attracted to the area and rapidly increase in number.

The Breakdown

They release toxins, including oxygen radicals, which increase membrane permeability and

phagocytize (ingest and destroy) the tissue debris that the calcium-mediated pathways released.

Neutrophils don¶t remain around more than a day or two, but are complimented by theappearance of monocytes also attracted to the damaged area. Monocytes (a type of phagocyticcell) enter the damaged muscle and form into macrophages (another phagocytic cell) that also

release toxins and phagocytize damaged tissue. Once the phagocytic stage commences, thedamaged fibers are rapidly broken down by lysosomal proteases, free O2 radicals, and other

substances produced by macrophages. The muscle is now in a weaker state than before it wastrained. Incidently, macrophages have an essential role in initiating tissue repair. Unless

damaged muscle is invaded by macrophages, activation of satellite cells and muscle repair doesnot occur. Also, increased intracellular Ca++ concentrations are known to activate an enzyme

called phospholipase A2.

This enzyme releases arachidonic acid from the plasma membrane which is then formed intoprostaglandins (primarily PGE2) and other eicosanoids that contribute to the degradativeprocesses. So, now that we¶ve looked briefly at the process of post-exercise muscle degradation,

how does it grow?

The Process Of Exercise-InducedMuscle Growth

Muscle cells have many nuclei and other intracellular organelles. This is because nuclei are

intimately involved in the protein synthesis process (don¶t forget, actin and myosin are proteins),and a single nuclei can only support the manufacturing of a limited amount of protein. If muscle

cells didn¶t have multiple nuclei they would be very small muscle cells indeed. So if a muscle isto grow beyond its current size (i.e. synthesize contractile proteins ± actin and myosin) it has to

increase the number of nuclei that it contains (called the µmyonuclei number¶).

How does it do this?



Around the muscle cells are myogenic stem cells called µsatellite cells¶ (or µmyoblasts¶). Under the right conditions these cells become more µlike¶ muscle cells and actually donate their nuclei

to the muscle fibers, thereby increasing myonuclei number. For this to happen, several thingsneed to take place. One, the number of satellite cells has to increase (called µproliferation¶). Two,

they have to become more µlike¶ muscle cells (called µdifferentiation¶). And three, they have to

fuse with the needy muscle cells.When the sarcolemma (the muscle cell wall) is µdamaged¶ by tension (as in weight training or even stretching) growth factors are produced and released in the cell. There are several different

types of growth factors. The most significant are:

y Insulin-like Growth Factor 1 (IGF-1)y Fibroblast Growth Factor (FGF)

y Transforming Growth Factor -Beta Superfamily (TGF-beta)

These growth factors can then leave the cell and go out into the surrounding area becausesarcolemma permeabilty has been increased due to the µdamage¶ done during contraction. Once

outside the muscle cell these growth factors cause the satellite cells to proliferate (mainly FGFdoes this) and differentiate (mainly IGF-1 does this). TGF-beta¶s role is one of mediation ± in

this case it inhibits growth. After this process the satellite cells then fuse with the muscle cellsand donate their nuclei, giving the muscle cells the µability¶ to grow.

Now factors that promote protein synthesis such as IGF-1, growth hormone (GH), testosteroneand some prostaglandins can commence the growth process. Protein synthesis occurs because a

genetically-coded substance called µmessenger RNA¶ (mRNA) is sent out from the nucleus to theribosomes. The nucleus is believed to release increased mRNA in response to tension and/or

myofibrillar damage done as a result of insufficient cycling of actin-myosin cross-bridges duringintense muscular contractions, though this mechanism is not fully understood.

The mRNA contains the µinstructions¶ for the ribosomes to synthesize proteins, and so theprocess of constructing contractile (actin and myosin) and structural proteins (for the other

components of the cell) from the amino acids taken into the cell from the bloodstream is set off.

Several substances can influence this process. A short overview of the major ones are foundbelow:

IGF-1:

IGF-1 comes in two varieties ± paracrine IGF-1 is made primarily in the liver and autocrine IGF-1 is made locally in other cells. Paracrine IGF-1 travels through the bloodstream to the varioustissues of the body, but autocrine IGF-1 is local in that in affects only tissues in the area in which

it is released. Receptors on the surface of the cells are necessary for paracrine IGF-1 to enter thecells and exert its anabolic effects. But autocrine IGF-1, which is manufactured and released in

the muscle cell as a response to high tension contractions, operates independently of receptors onthe surface because it¶s already inside. Once inside the cell, IGF-1 interacts with calcium-

activated enzymes and sets off a process that results in protein synthesis (and the calcium ions



intense µconventional¶ Bodybuilding-type weight training. This is strong evidence to support theidea that muscles should be trained every 48 hours. Clearly, increasing the volume of muscular

contractile elements is the key to increasing muscle size and strength. Since the type II fiberscontain the most actin/myosin filaments, and generate the highest tensions, they have the greatest

potential for strengthening/growth.

The prerequisite, of course, is that you have to lift weights heavy enough to recruit the type IIfibers ± and for them to twitch fast enough to develop significant tension. You also have to

subject them to that tension long enough for significant damage to occur to the

The Science Of BuildingMuscle

The science of building muscle: this groundbreaking article will help you get the most out of

your workout by breaking down the critical components of each rep

Sets are competitions with yourself. They¶re finite journeys taken again and again. Broken down

into reps and stacked together to form workouts, they¶re training¶s fundamental unit of measurement. They¶re like miniature lives, beginning with vigor, but debilitating with time andrepetition, and always, eventually, ending. They¶re regimented periods of joy and pain, and, at

their best, they deliver an aching sense of accomplishment we¶ll call ³joyous pain.´ They¶re allthat and more, and they¶re the very essence of bodybuilding, so it¶s remarkable that they¶reseldom considered in depth.

What happens to your body during a set? Why do your muscles fail? What physiological factors

dictate the very essence of bodybuilding? And, most important, what steps can you take toenhance your sets and eke out invaluable extra reps?

Here, in a step-by-step format, are the answers.

Prepare For Liftoff

It doesn¶t matter what the exercise is. You slide plates on a bar, set a pin in a machine¶s weight

stack or pick the right dumbbells, and before you even begin the first set, your body is preparingitself for the onslaught that awaits. Your sympathetic nervous system releases norepinephrine,

a.k.a. noradrenaline, from specialized nerve fibers that innervate your heart, thus boosting your

heart rate. Your adrenal glands secrete epinephrine, a.k.a. adrenaline, along with some NE,which travels via your blood to your heart to ramp up the rate and force of its contractions. NEand EPI also increase the force of muscle contractions, resulting in greater strength. Your

testosterone starts to rise. Secreted from your testicles into your bloodstream, it travelsthroughout your body to different tissues. It causes nerve signals to rush more rapidly to muscles,

thus, like NE and EPI, increasing the force of muscle contractions.

Boost Tactic



The more you focus on the set before you even begin, the more NE, EPI and testosterone youwill produce, allowing you to lift heavier weight and complete more reps. In addition, targeting

the muscles you¶ll work in the set by performing an isometric hold can increase strength. This iscalled postactivation potentiation, and it¶s believed to work by ramping up the nervous system so

it fires more rapidly during the set.

As an example of how to perform this hold before barbell curls, position a Smith machine bar ata height that replicates the curl¶s halfway point (arms at 90 degrees). So it won¶t move, load the

bar with more weight than you can curl once. Then, as if doing a curl, pull up against thestationary bar (without unhooking it) as hard as you can for 20 seconds. Rest for two to three

minutes, then do your set of barbell curls.

Start Of The Set

As you begin the first of a probable 10 reps, you have high energy and are pain free, and the

weight feels relatively light. Your muscles must contract to move the weight. Contraction occurs

in muscle fibers when specialized structural proteins called actin and myosin interact with eachother. The motor nerves send a signal that causes sodium to enter muscle fibers and potassium torush out. This process, known as depolarization, basically changes the electrical charge of the

fibers and triggers the release of calcium into the cells, causing the myosin to attach to the actinso it can pull it in. This shortens the muscles and moves the weight. The farther the myosin pulls

in the actin, the more the muscles contract.

During the first rep, your motor nerves call primarily on slow-twitch fibers.

These are much weaker than the bigger fast-twitch fibers, but since fast-twitch fibers fatigue

rapidly, the body knows to save them for when a set gets tough. The slow-twitch fibers contract

by pulling the actin in farther and farther until the weight is lifted as high as desired. As youlower the weight, the muscles resist it by allowing the actin to slide slowly back toward itsoriginal position.

Boost Tactic

Focus on the working muscles. Research shows that athletes who focus in that way during a setcan recruit more muscle fibers.

TheMidpoint

With each progressive rep, the weight becomes increasingly harder to lift. At the midpoint, younotice your strength and energy starting to wane and feel the first hints of pain. As the body

exhausts slow-twitch muscle fibers, it recruits more of them and also starts to get help from fast-twitch fibers. Myosin requires energy to keep these fibers contracting rep after rep. This is

supplied in the form of adenosine triphosphate, which is created in the muscle primarily by



creatine phosphate. Creatine donates high-energy phosphate to form ATP, and ATP then passesit on to myosin to attach to actin and pull it in. During weight lifting, the muscles also make ATP

by breaking down glucose in a chemical reaction known as glycolysis.

Many bodybuilders believe that each rep they perform brings more blood to working muscles,

thus giving them a pump.

In fact, reps actually squeeze blood out of muscles. When a muscle contracts, it creates so much

pressure on the tiny blood vessels that feed its fibers that it reduces blood flow to itself. Althoughmuscle blood flow increases after a set, the pump you feel during a set is due to water. Each

contraction produces more metabolic waste products, and sodium collects in the muscles. Thisbuildup causes water from outside the cells, as well as water from the blood, to rush into muscle

cells, as if filling a water balloon.

Boost Tactic:

To increase intermuscular creatine during exercise, ingest five grams of creatine within 30minutes of your workout (along with 20 g of protein and 20-40 g of slow-digesting carbs). Toaugment blood flow to the muscles, take 3-5 g of arginine 30-60 minutes before the workout.

Enhanced blood flow means more water is delivered to the muscles between sets and then drawninto the muscles for a greater pump. Creatine, glutamine and taurine also draw water into

muscles.

Near Failure

You start to falter on the seventh rep, struggling to move the weight up at your previous brisk pace. Your energy is quickly diminishing. A rapidly rising burning sensation floods your

working muscles as you grind out the eighth rep. The immense power you felt just two reps agois now gone. The ninth rep is harder still, but you gut it out, running through the stop signs. By

the 10th rep, the lactic-acid-induced pain has your muscles blasting off nerve impulses likefrantic 911 calls, demanding you halt the set. You seem to have virtually no strength or energy

left, but you clench your eyes shut, trying your best to block out the pain and focus on your muscles. The weight slowly rises a 10th time.

During the final reps, your body starts calling on more fast-twitch muscle fibers, which exhaust

quickly, accounting for your feeling of boundless strength and energy dissipating so rapidly from

one rep to the next. The heavier the weight and the more reps you perform, the harder it is for themyosin and actin to extend under the force of the weight, and, in some muscle fibers, the actinliterally rips away from the myosin, like Velcro being torn apart. This damages the muscle fibers

at the molecular level.

Glycolysis not only provides ATP, but it also creates lactic acid±traditionally seen as the greatvillain in gyms everywhere, for it was the one metabolic byproduct that seemed to be responsible

for ending the set. Lactic acid is the reason your muscles burn during and after a grueling



workout. It creates an acidic environment, and it may indeed halt your set. It does, however, havea good side: it seems to trigger growth hormone release. As lactic acid levels rise, so does your

GH response. Lactic acid is also a substrate that can be used for fuel. New research suggestslactic acid may even help muscles contract more forcefully.

Boost

Tactic

As you approach failure, you need to focus intensely on the task and fight through the pain.

Research shows that taking 200 milligrams of caffeine before workouts blunts muscle painduring exercise. One study even found that caffeine reduces pain more effectively than aspirin.

Failure

After your final rep±when you cannot, no matter how hard you try, grind out one more±the fibershave become fatigued and can no longer contract. The myosin and actin slowly struggle to

extend and return the weight back to the starting position, and some fibers may have ripped

apart.

New research suggests that a set may end for a reason other than lactic acid buildup. As wasmentioned, when muscles receive signals to contract, sodium is moved into the cells while

potassium flows out. As you perform more reps (and more sets during your workout), sodiumlevels start to build up in muscles, while potassium levels continually decline.

Sodium/potassium pumps help offset these changes by moving electrolytes back in and out of the

cells, but during intense exercise, the pumps can¶t keep up with the large changes in electrolyteconcentrations. The result is a decline in the amount of force muscles can produce, which leads

to fatigue and, ultimately, failure.

Boost Tactic

Take 600-1,000 mg of N-acetylcysteine before workouts to delay fatigue by enhancing

sodium/potassium pumps. Pushing a set beyond failure via techniques like forced reps and dropsets ensures the recruitment of as many muscle fibers as possible, allowing for more muscle

growth.

Aftermath

After your set, the acidic environment caused by lactic acid is buffered mainly by bicarbonate,thus rapidly diminishing or eliminating pain before your next one. Simultaneously, fat is burnedto produce ATP, which donates a phosphate to creatine and restores creatine phosphate levels,

giving you quick energy for another set. The spike in lactic acid levels at the end of your setsignals your body to release GH, which enhances fat burning and initiates muscle regeneration

and growth. Likewise, testosterone levels have risen during the set, which will further aid theprocess of muscle regeneration and muscle building.



Cellular damage has also caused the muscle to flood with proteins which further break down thedamaged structures.

This starts an inflammatory cascade of white blood cells that serve numerous functions, such as

the removal of broken-down muscle tissue so that new and stronger tissue can be built up in its

place. That process takes a few days to complete; 24 to 48 hours after your workout, if yousuffered enough damage, you will likely feel the effects of calcium and prostaglandins, whichbuild up in the muscle fibers, sensitizing nerve cells that signal your brain and thus providing the

lingering ache known as delayed onset muscle soreness.

Boost Tactic

Postworkout, consume 40 g of whey protein and 60-100 g of fast-digesting carbs to enhance

muscle recovery and blunt DOMS. Taking 5-10 g of glutamine can help increase GH levels. Amassage may speed recovery, as can low-intensity activities (such as walking, cycling and

swimming).

The Next Set

A minute or two after your set, you¶re ready to do it all over again. You grab the barbell, the

dumbbells or the handle once more. You focus entirely on the targeted muscles. The inevitablepain is like a false fire alarm, extreme heat that never sparks a flame, so you vow not to let it

distract you. You know every set has to end, but you feel limitless strength and energy onceagain. Hope springs eternal, and the life of a set is born anew as you lower the weight, launching

the first rep of the next set

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