Lecture 2Lecture 2

CVS in exerciseCVS in exercise- CVS serves 5 import func during ex;- CVS serves 5 import func during ex;1) Delivers O1) Delivers O22 to working muscles to working muscles2) Oxygenates blood by returning it to the lungs2) Oxygenates blood by returning it to the lungs3) Transports heat from the core to the skin3) Transports heat from the core to the skin4) Delivers nutrients and fuel to active tissues4) Delivers nutrients and fuel to active tissues5) Transports hormones 5) Transports hormones

- Due to ex the following changes take place;- Due to ex the following changes take place;* * ↑↑ demand on the CVS demand on the CVS ** ↑ ↑ O O22 demand by the muscles demand by the muscles* Speed up metabolic processes * Speed up metabolic processes * * ↑↑ waste production waste production* * MoreMore nutrients are used nutrients are used * * ↑↑ BT BT To perform as efficiently as possible the CVS must To perform as efficiently as possible the CVS must regulate the changes and meet the body’s regulate the changes and meet the body’s increasing demands. increasing demands.

- Training sig improve the CV performance. Trained athletes - Training sig improve the CV performance. Trained athletes have bigger hearts and larger SV than do non athletes and have bigger hearts and larger SV than do non athletes and these are important functional differences (see the table).these are important functional differences (see the table).

At rest, 15-20% of blood goes to skeletal muscle; during At rest, 15-20% of blood goes to skeletal muscle; during exercise, this amount increases to 80-85% of Q. exercise, this amount increases to 80-85% of Q.

- Due to the delivery of O2 to the working muscles, the - Due to the delivery of O2 to the working muscles, the muscle BF can muscle BF can ↑ approx 25-fold during strenuous ex. ↑ approx 25-fold during strenuous ex. 2 reasons for the ↑ in flow;2 reasons for the ↑ in flow;1- intramuscular vasodilation caused by the direct effect of ↑ muscle 1- intramuscular vasodilation caused by the direct effect of ↑ muscle metabolism. metabolism. 2- multiple factors, such as ↑ in arterial BP that occurs in ex, usually 2- multiple factors, such as ↑ in arterial BP that occurs in ex, usually about a 30% ↑.about a 30% ↑.

2 major adjustments to BF must occur to meet the metab 2 major adjustments to BF must occur to meet the metab demands of skeletal muscle during ex. 1) Q from the H demands of skeletal muscle during ex. 1) Q from the H must must ↑↑. . 2) BF from inactive organs and tissues must be 2) BF from inactive organs and tissues must be redistributed to active skeletal muscle.redistributed to active skeletal muscle.

Normal BP at rest varies 110-140 mmHg (systolic BP) Normal BP at rest varies 110-140 mmHg (systolic BP) and 60-90 mmHg (diastolic BP).and 60-90 mmHg (diastolic BP).During ex, systolic pres may ↑ to 200-250 mmHg while During ex, systolic pres may ↑ to 200-250 mmHg while diastolic pres remains relatively unchanged regardless of diastolic pres remains relatively unchanged regardless of ex intensity.ex intensity.An ↑ of more than 15 mmHg may indicate a CHD.An ↑ of more than 15 mmHg may indicate a CHD.

- The ↑ in pres → forces more blood through the BV , - The ↑ in pres → forces more blood through the BV , stretches the walls of the arterioles and reduces the stretches the walls of the arterioles and reduces the vascular resistance. vascular resistance.

A linear relation of work output, VOA linear relation of work output, VO22 & Q occurred → & Q occurred → VOVO22 in turn dilates the muscle BV → ↑ venous return and in turn dilates the muscle BV → ↑ venous return and Q. Q.

Fig 84-9Fig 84-9

- Normal Q at rest is approx 5-6 L/min, and may ↑ - Normal Q at rest is approx 5-6 L/min, and may ↑ to 30-40 L/min during heavy ex (table 21-2). This to 30-40 L/min during heavy ex (table 21-2). This ↑ is achieved by ↑ of both SV & HR.↑ is achieved by ↑ of both SV & HR.Q = SV X HRQ = SV X HRQ is the amount of blood pumped by the H in 1 Q is the amount of blood pumped by the H in 1 min measured in L/min.min measured in L/min.SV is amount of blood ejected/b from left SV is amount of blood ejected/b from left ventricle & measured in ml/beat.ventricle & measured in ml/beat.

- Fig 84-10 shows the approx changes in SV & HR - Fig 84-10 shows the approx changes in SV & HR as the Q ↑ from its resting level to a marathon as the Q ↑ from its resting level to a marathon runner. The SV ↑ from 105 to 162 ml, whereas runner. The SV ↑ from 105 to 162 ml, whereas HR ↑ from 50 to 185 bpm. Therefore, the HR HR ↑ from 50 to 185 bpm. Therefore, the HR accounts by far for a greater proportion of the ↑ accounts by far for a greater proportion of the ↑ in Q than does the ↑ in SV during strenuous ex. in Q than does the ↑ in SV during strenuous ex.

Table 21-2Table 21-2

Fig 84-10Fig 84-10

- -

- CVS is normally much more limiting on - CVS is normally much more limiting on VOVO22max than is the RS, because Omax than is the RS, because O22

utilization by the body can never be more utilization by the body can never be more than the rate at which the CVS can than the rate at which the CVS can transport Otransport O22 to the tissues. to the tissues.

VOVO22 max is the rate of O max is the rate of O22 under max under max

aerobic metabolism.aerobic metabolism.

Exercise and CV diseaseExercise and CV disease- Regular ex has several beneficial effects. Even - Regular ex has several beneficial effects. Even moderate ex routine can lower total blood choles levels.moderate ex routine can lower total blood choles levels.

- A high choles level of the major risk factors for - A high choles level of the major risk factors for atherosclerosis, which leads to CV disease and stroke.atherosclerosis, which leads to CV disease and stroke.

- A regular ex, a healthy lifestyle, a balanced diet, weight - A regular ex, a healthy lifestyle, a balanced diet, weight control and not smoking control and not smoking → reduces stress, lowers BP and → reduces stress, lowers BP and slows the formation of plaque.slows the formation of plaque.

- A regular mod ex may cut the incidence of HA 50%.- A regular mod ex may cut the incidence of HA 50%.

- Ex is also beneficial in accelerating one’s recovery after - Ex is also beneficial in accelerating one’s recovery after a HA.a HA.

- Regular light to mod ex coupled with a low fat diet and - Regular light to mod ex coupled with a low fat diet and a low stress lifestyle, not only reduces symptoms of CAD a low stress lifestyle, not only reduces symptoms of CAD (e.g. angina) but also improves one’s mood and overall (e.g. angina) but also improves one’s mood and overall quality of life. quality of life.

Exercise & immune systemExercise & immune system- Mod ex has a beneficial effect on overall health and may - Mod ex has a beneficial effect on overall health and may reduce the incidence of minor infectious disease. However, reduce the incidence of minor infectious disease. However, exhaustive ex does not promote disease resistance and exhaustive ex does not promote disease resistance and may even reduce immune response.may even reduce immune response.

- Intensive ex has been found to reduce both the levels of - Intensive ex has been found to reduce both the levels of antibody secretion by B lymphocytes and the effectiveness antibody secretion by B lymphocytes and the effectiveness of T lymphocytes.of T lymphocytes.

- Recent research indicates that fit people tend to have - Recent research indicates that fit people tend to have higher No. of NK cells in their circulation. NK cells are an higher No. of NK cells in their circulation. NK cells are an important part of our immune defence mechanisms against important part of our immune defence mechanisms against viral infect and some bacterial infect. NK cells are able to viral infect and some bacterial infect. NK cells are able to destroy the cells of our body that become infected with destroy the cells of our body that become infected with these disease-causing micro-organisms. There is some these disease-causing micro-organisms. There is some evidence that in the elderly a mod degree of physical evidence that in the elderly a mod degree of physical activity (e.g. regular walking) confers some protection activity (e.g. regular walking) confers some protection against picking up infections of the upper respiratory tract against picking up infections of the upper respiratory tract compared with a sedentary lifestyle. compared with a sedentary lifestyle.

Warning signsWarning signsIf you experience any of the following symptoms, If you experience any of the following symptoms, stop exercising and seek medical help: stop exercising and seek medical help: Extreme breathlessness Extreme breathlessness Breathing problems such as wheezing or Breathing problems such as wheezing or coughing coughing Chest pain or pressure Chest pain or pressure Extreme perspiration Extreme perspiration Dizziness, fainting Dizziness, fainting Severe muscle pain or cramps Severe muscle pain or cramps Nausea Nausea Severe pain in any muscles or joints Severe pain in any muscles or joints Extreme and long-lasting fatigue after exercising.Extreme and long-lasting fatigue after exercising.