EXERCISE PHYSIOLOGYEXERCISE PHYSIOLOGY(Human Physiology 2)(Human Physiology 2)

PhysiotherapyPhysiotherapy

Dr. Waheeb AlharbiDr. Waheeb Alharbi

ReferencesReferences

(1) Physiological basis of medical practice(1) Physiological basis of medical practice

By; John B. WestBy; John B. West

(2) Textbook of Medical physiology (2) Textbook of Medical physiology

By; Arthur C. Guyton & John E. HallBy; Arthur C. Guyton & John E. Hall

Exercise and your bodyExercise and your body

During ex, the body is trying to tell During ex, the body is trying to tell you something to do. There has to be you something to do. There has to be a purpose to these changes a purpose to these changes (occurred during ex) or else the body (occurred during ex) or else the body would not bother. So simply your would not bother. So simply your body is saying "If you are going to be body is saying "If you are going to be doing this, I need extra resources". doing this, I need extra resources".

How does our body response to exerciseHow does our body response to exercise

The following changes may occur;The following changes may occur;

- Your heart beats become faster - Your heart beats become faster

- Your breathing become more deeply and - Your breathing become more deeply and more frequently more frequently

- You start sweating and feeling hot - You start sweating and feeling hot

- You start feeling thirsty - You start feeling thirsty

- Your skin become flushed- Your skin become flushed

- You can feel your pulse beating - You can feel your pulse beating

- Your muscles may begin to ache - Your muscles may begin to ache

- You may feel light headed.- You may feel light headed.

(1) Faster heart beats & stronger pulse feeling :(1) Faster heart beats & stronger pulse feeling :

- The heart is a muscle and its function is to pump - The heart is a muscle and its function is to pump blood around your body.blood around your body.- Blood is the transport system for your body and - Blood is the transport system for your body and carries the fuel and nutrients your body requires. carries the fuel and nutrients your body requires. - The heart size is like the size of a clenched fist - The heart size is like the size of a clenched fist and weighs about 300g.and weighs about 300g. At rest the HR averages about 60-80 bpm in a At rest the HR averages about 60-80 bpm in a healthy adults. healthy adults. During moderate ex your heart will respond to the During moderate ex your heart will respond to the ↑↑ demands for resources by slightly enlarging demands for resources by slightly enlarging →→ thus allowing more blood to enter your heart, and thus allowing more blood to enter your heart, and by by ↑↑ the No. of bpm. This allows more blood to be the No. of bpm. This allows more blood to be pumped around your body (i.e. 80 x 130 = 10.4 pumped around your body (i.e. 80 x 130 = 10.4 L). As the intensity of your ex L). As the intensity of your ex ↑↑ (e.g. you have to (e.g. you have to sprint) HR increases still further so more blood sprint) HR increases still further so more blood can be circulated (e.g. 80 x 170 = 13.6 L).can be circulated (e.g. 80 x 170 = 13.6 L).

(2) Deeper and more frequent breathing(2) Deeper and more frequent breathing

- Because your body is asking for more O- Because your body is asking for more O22 to cope to cope with the demand for a greater fuel supply to your with the demand for a greater fuel supply to your working muscles. working muscles. - The O- The O22 you require is breathed in through your you require is breathed in through your nose and mouth and passes down your bronchial nose and mouth and passes down your bronchial tubes and into your lungs which are made up of tubes and into your lungs which are made up of over 300 million tiny air sacs called Alveoli. It is over 300 million tiny air sacs called Alveoli. It is here the Ohere the O22 transfers itself to your blood to be transfers itself to your blood to be transported around your body.transported around your body.- At rset, you usually breathe in about 500ml/b and - At rset, you usually breathe in about 500ml/b and you do this 12 times/min. This would give you 6 L of you do this 12 times/min. This would give you 6 L of air. When you are exercising it is quite reasonable air. When you are exercising it is quite reasonable to take in 2300ml/b and your BR could to take in 2300ml/b and your BR could ↑↑ 2 or 3 2 or 3 times.times.- Slow deep breathing is more efficient than rapid - Slow deep breathing is more efficient than rapid shallow breathing in increasing air flow to your shallow breathing in increasing air flow to your lungs. lungs.

(3) Sweating, feeling hot & flushed(3) Sweating, feeling hot & flushed- When you exercise the muscles are used more - When you exercise the muscles are used more and as a result produce heat. This heat needs to and as a result produce heat. This heat needs to be dissipated and your body loses heat in 2 be dissipated and your body loses heat in 2 principal ways. principal ways. A) Your sweat glands are stimulated to secrete A) Your sweat glands are stimulated to secrete fluid, which then evaporates on the surface of fluid, which then evaporates on the surface of your body to produce a cooling effect. your body to produce a cooling effect. B) Your small BV near to the surface of your skin B) Your small BV near to the surface of your skin enlarge to allow more blood to flow closer to the enlarge to allow more blood to flow closer to the surface where cooling can take place. This is what surface where cooling can take place. This is what makes you feel "flushed". Your body is telling you makes you feel "flushed". Your body is telling you it wants to cool down so you should help it.it wants to cool down so you should help it.- On a hot day you should try and wear a short-- On a hot day you should try and wear a short-sleeved shirt, or at least have the sleeves rolled sleeved shirt, or at least have the sleeves rolled up, to allow more skin surface to be exposed to up, to allow more skin surface to be exposed to the air. the air.

(4) Feeling thirsty(4) Feeling thirsty

- Ex will - Ex will ↑↑ the temp of your body which will try to the temp of your body which will try to reduce it by secreting fluids. These fluids come reduce it by secreting fluids. These fluids come from the reservoir of fluids contained in your from the reservoir of fluids contained in your body. If the fluids are not replaced, the level in body. If the fluids are not replaced, the level in the reservoir will go down and eventually this will the reservoir will go down and eventually this will trigger a feeling of thirst. trigger a feeling of thirst. - Prolonged periods of intensive ex can result in - Prolonged periods of intensive ex can result in fluid losses of up to 2-3 L fluid losses of up to 2-3 L →→ dehydration which dehydration which will not only adversely affect performance but can will not only adversely affect performance but can also be dangerous.also be dangerous.

- Fluid, esp H- Fluid, esp H22O, should be regularly consumed O, should be regularly consumed before, during and after training or matches to before, during and after training or matches to continually top up your reservoir and prevent you continually top up your reservoir and prevent you feeling thirsty. feeling thirsty.

(5) Muscle Ache(5) Muscle Ache- In moderate ex your body may be able to - In moderate ex your body may be able to remove the waste materials as they are remove the waste materials as they are produced, but as the intensity or length of the produced, but as the intensity or length of the activity activity ↑↑, the build up of these waste products , the build up of these waste products occurs faster than they can be removed. occurs faster than they can be removed. - The waste materials occupy space previously - The waste materials occupy space previously available to the fuel and nutrients in your blood, available to the fuel and nutrients in your blood, so as they build up, your blood supply to carry so as they build up, your blood supply to carry them away them away ↓↓. Without O. Without O22 and nutrients the and nutrients the efficiency of your muscles diminishes, waste efficiency of your muscles diminishes, waste products swell your muscle, and muscle soreness products swell your muscle, and muscle soreness ensues. ensues. - When such soreness occurs, stretching the - When such soreness occurs, stretching the muscles involved will assist in reducing the pain muscles involved will assist in reducing the pain and discomfort. and discomfort.

(5) Feeling light headed(5) Feeling light headed

- Normally blood is circulating to all parts of your - Normally blood is circulating to all parts of your body. When demand body. When demand ↑↑ for more fuel to be taken for more fuel to be taken to working muscles, your body responds by to working muscles, your body responds by reducing your blood supply to some organs not reducing your blood supply to some organs not immediately involved in the activity. It is then immediately involved in the activity. It is then redistributed to the areas in need. This means redistributed to the areas in need. This means that organs such as your liver and stomach will that organs such as your liver and stomach will have their blood supply reduced so that more have their blood supply reduced so that more blood can be taken to your muscles.blood can be taken to your muscles.- Your brain is another part of your body that - Your brain is another part of your body that finds itself having to deal with a reduced BF and finds itself having to deal with a reduced BF and the diminished Othe diminished O22 supply may well make you feel supply may well make you feel light-headed and cause your conc to lapse. In light-headed and cause your conc to lapse. In severe cases it could cause you to collapse.severe cases it could cause you to collapse.

Respiration in exerciseRespiration in exercise

VOVO22 & V & VEE in exercise; in exercise;- Normal VO- Normal VO22 for a young man at rest is about for a young man at rest is about 250ml/min. However, under maximal conditions, 250ml/min. However, under maximal conditions, this can be this can be ↑ 8-20 times, such as↑ 8-20 times, such asin untrained average male may reach 3600 ml/minin untrained average male may reach 3600 ml/minin trained average male may reach 4000 ml/minin trained average male may reach 4000 ml/minin male marathon runner may reach 5100 ml/minin male marathon runner may reach 5100 ml/min

- This ↑ is reflected in a similar ↑ in V- This ↑ is reflected in a similar ↑ in VEE, which ↑ from , which ↑ from 5600 ml/min to as much as 120000-140000 ml/min. This 5600 ml/min to as much as 120000-140000 ml/min. This ↑ is due to the ↑ in both V↑ is due to the ↑ in both VTT & fr (figure 18-B). V & fr (figure 18-B). VTT can be can be as much as 50% of the VC and is mostly taken from as much as 50% of the VC and is mostly taken from inspiratory reserve.inspiratory reserve.

- ↑ in V- ↑ in VEE → ↑ the elastic and flow-resistive work of → ↑ the elastic and flow-resistive work of breathing → ↑ the total energy requirement for breathing.breathing → ↑ the total energy requirement for breathing.

Figure 18-BFigure 18-B

- Ex - Ex ↑ the diffusion capacity of the lungs. The ↑ results from the ↑ the diffusion capacity of the lungs. The ↑ results from the greater expansion of the lungs and also from improvement of the greater expansion of the lungs and also from improvement of the VE/Perf ratio, which results from ↑ BF through the lungs.VE/Perf ratio, which results from ↑ BF through the lungs.

- O- O22 diffusing capacity is a measure of the rate at which O diffusing capacity is a measure of the rate at which O22 can can diffuse from the pulmonary alveoli into the blood. This is diffuse from the pulmonary alveoli into the blood. This is expressed in terms of ml of Oexpressed in terms of ml of O22 that will diffuse each min for each that will diffuse each min for each mmHg difference between PmmHg difference between PAAOO22 and pulmonary blood O and pulmonary blood O22 pressure.pressure.- The normal diffu capac in a nonathlete at rest is 23 ml/min, - The normal diffu capac in a nonathlete at rest is 23 ml/min, nonathlete during max ex is 48 ml/min. This amount may ↑ to 64 nonathlete during max ex is 48 ml/min. This amount may ↑ to 64 ml/min in speed skater during max ex, 71 ml/min in swimmers ml/min in speed skater during max ex, 71 ml/min in swimmers during max ex and 80 ml/min in oarsman during max ex.during max ex and 80 ml/min in oarsman during max ex.

- These results mainly from the fact that BF through - These results mainly from the fact that BF through many of the pulm cap is sluggish or even dormant in the many of the pulm cap is sluggish or even dormant in the resting state, whereas in max ex, resting state, whereas in max ex, ↑ BF through the lungs ↑ BF through the lungs causes all the pulm cap to be perfused at their max rate, thus causes all the pulm cap to be perfused at their max rate, thus providing a far greater surface are through which Oproviding a far greater surface are through which O22 can diffuse can diffuse into the pulm cap blood.into the pulm cap blood.

- There is a linear relation between VO- There is a linear relation between VO22 & &

total Vtotal VEE (fig 84-6). Both VO (fig 84-6). Both VO22 & V & VEE ↑ approx ↑ approx

20-fold between the resting state and 20-fold between the resting state and maximal intensity of ex in the well-trained maximal intensity of ex in the well-trained athlete.athlete.

Figure 84-6Figure 84-6

Blood gases during exercise;Blood gases during exercise;- BG do not always have to become abnormal for - BG do not always have to become abnormal for resp to be stim in ex. Instead, resp is stim mainly resp to be stim in ex. Instead, resp is stim mainly by neurogenic mech during ex.by neurogenic mech during ex.Part of this stim results from direct stim of the Part of this stim results from direct stim of the respiratory center by the same nervous signals respiratory center by the same nervous signals that are transmitted from the brain to the that are transmitted from the brain to the muscles to cause the ex.muscles to cause the ex.An additional part is believed to result from An additional part is believed to result from sensory signals transmitted into the respiratory sensory signals transmitted into the respiratory center from the contracting muscles and moving center from the contracting muscles and moving joints. All this extra nervous stim is normally joints. All this extra nervous stim is normally sufficient to provide almost exactly the necessary sufficient to provide almost exactly the necessary ↑ in V↑ in VEE required to keep the blood respiratory gases very required to keep the blood respiratory gases very near to normal.near to normal.

CVS in exerciseCVS in exercise- CVS serves 5 important functions during - CVS serves 5 important functions during exercise;exercise;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

- Ex places an - Ex places an ↑↑ demand on the CVS. O demand on the CVS. O22 demand demand by the muscles by the muscles ↑↑ sharply. Metabolic processes sharply. Metabolic processes speed up and more waste is created. More speed up and more waste is created. More nutrients are used and body temp nutrients are used and body temp ↑↑. To perform . To perform as efficiently as possible the CVS must regulate as efficiently as possible the CVS must regulate these changes and meet the body’s increasing these changes and meet the body’s increasing demands. demands.

- A key requirement of CV func in ex is to deliver - A key requirement of CV func in ex is to deliver the required Othe required O22 and other nutrients to the and other nutrients to the exercising muscles. For this purpose, the muscle exercising muscles. For this purpose, the muscle BF can BF can ↑ a maximum of approx 25-fold during strenuous ↑ a maximum of approx 25-fold during strenuous ex. Almost one half this ↑ in flow results from ex. Almost one half this ↑ in flow results from intramuscular vasodilation caused by the direct effectof ↑ intramuscular vasodilation caused by the direct effectof ↑ muscle metabolism. The remaining ↑ results from muscle metabolism. The remaining ↑ results from multiple factors, the most important of which is probably multiple factors, the most important of which is probably the moderate ↑ in arterial BP that occurs in ex, usually the moderate ↑ in arterial BP that occurs in ex, usually about a 30% ↑.about a 30% ↑.

- The ↑ in pressure not only forces more blood through - The ↑ in pressure not only forces more blood through the BV but also stretches the walls of the arterioles and the BV but also stretches the walls of the arterioles and further reduces the vascular resistance. further reduces the vascular resistance.

Figure 84-9 shows the interrelations among work output, Figure 84-9 shows the interrelations among work output, VOVO22 & Q during ex. All these parameters are related & Q during ex. All these parameters are related directly to one another (linear function), because the directly to one another (linear function), because the muscle workout ↑ VOmuscle workout ↑ VO22 and VO and VO22 in turn dilates the muscle in turn dilates the muscle BV → ↑ venous return and Q. BV → ↑ venous return and 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 ↑ is to 30-40 L/min during heavy ex (table 21-2). This ↑ is achieved by ↑ of both SV & HR.achieved by ↑ of both SV & HR.

- Fig 84-10 shows the approx changes in SV & HR as - Fig 84-10 shows the approx changes in SV & HR as the Q ↑ from its resting level to a marathon runner. The the Q ↑ from its resting level to a marathon runner. The SV ↑ from 105 to 162 ml, whereas HR ↑ from 50 to 185 SV ↑ from 105 to 162 ml, whereas HR ↑ from 50 to 185 bpm. Therefore, the HR accounts by far for a greater bpm. Therefore, the HR accounts by far for a greater proportion of the ↑ in Q than does the ↑ in SV during proportion of the ↑ in Q than does the ↑ in SV during strenuous ex. strenuous ex. - The SV normally reaches its maximum by the - The SV normally reaches its maximum by the time Q has time Q has ↑ only half way to its maximum. Any further ↑ only half way to its maximum. Any further ↑ in Q must occur by ↑ HR.↑ in Q must occur by ↑ HR.

Table 21-2Table 21-2

Fig 84-10Fig 84-10

- During max ex, both SV & HR are - During max ex, both SV & HR are ↑ ↑ to about 95% of their max level.to about 95% of their max level.

- 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.

- Due to light ex the following changes take place;- Due to light ex the following changes take place;1) Extensive vasodilation occurs as the rate of 1) Extensive vasodilation occurs as the rate of VOVO22 in skeletal muscle in skeletal muscle ↑. Peripheral resistance drops, ↑. Peripheral resistance drops, BF through the cap ↑, and blood enters the venous BF through the cap ↑, and blood enters the venous system at an accelerated rate.system at an accelerated rate.2) The venous return ↑ as skeletal muscle contraction 2) The venous return ↑ as skeletal muscle contraction squeeze blood along the peripheral veins and an ↑ BR squeeze blood along the peripheral veins and an ↑ BR pulls blood into the venae cavae via the respiratory pulls blood into the venae cavae via the respiratory pump.pump.3) Q 3) Q ↑, primarily in response to; ↑, primarily in response to; a- the a- the ↑ in venous return↑ in venous returnb- atrial stretching (the atrial reflex).b- atrial stretching (the atrial reflex).

This regulation by venous feedback produces a This regulation by venous feedback produces a gradual gradual ↑ in Q to about double resting levels. Over the ↑ in Q to about double resting levels. Over the range of ↑, the BF to skeletal muscles, cardiac muscles range of ↑, the BF to skeletal muscles, cardiac muscles and skin rises. The ↑ flow to the muscles reflects the and skin rises. The ↑ flow to the muscles reflects the dilation of arterioles and precapillary sphincters in dilation of arterioles and precapillary sphincters in response to local factors; the ↑ flow to the skin occurs in response to local factors; the ↑ flow to the skin occurs in response to the rise in body temp.response to the rise in body temp.

At higher level of exertion, other physiological At higher level of exertion, other physiological adjustments occur as the cardiac and vasomotor centers adjustments occur as the cardiac and vasomotor centers call for the general activation of the SNS. Q ↑, toward call for the general activation of the SNS. Q ↑, toward maximal levels, and major changes in the peripheral maximal levels, and major changes in the peripheral distribution of blood take place, facilitating the BF to distribution of blood take place, facilitating the BF to active skeletal muscle. active skeletal muscle.

- During ex at max level, your blood - During ex at max level, your blood essentially races between the essentially races between the skeletal muscles and the lungs and skeletal muscles and the lungs and heart. Although BF to the most heart. Although BF to the most tissues is diminished, skin perfusion tissues is diminished, skin perfusion ↑ ↑ further, because the body temp continues further, because the body temp continues to climb. Only the blood supply to the brain to climb. Only the blood supply to the brain remains unaffected.remains unaffected.

Exercise, CV fitness & healthExercise, CV fitness & health

- CV performance improves sig with - CV performance improves sig with training. Table 21-3 compares the training. Table 21-3 compares the cardiac performance of athletes with cardiac performance of athletes with non athletes. Trained athletes have non athletes. Trained athletes have bigger hearts and larger SV than do bigger hearts and larger SV than do non athletes and these are important non athletes and these are important functional differences.functional differences.

Table 21-3Table 21-3

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 cholesterol moderate ex routine can lower total blood cholesterol levels.levels.

- A high cholesterol level of the major risk factors for - A high cholesterol 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 moderate ex may cut the incidence of heart - A regular moderate ex may cut the incidence of heart attack almost in half.attack almost in half.

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

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