Exercise Physiology

Question 1

what are the two types of exercise

Answer 1

dynamic

static

Question 2

what is dynamic exercise

Answer 2

• This is the rhythmical movement of joints and contraction and relaxation of muscles – such as swimming, running and cycling

Question 3

what is static exercise

Answer 3

• Static – maintained contraction for a length of time – weight lifting

Question 4

what is the energy requirements of the exercising muscle

Answer 4

• At rest skeletal muscle has relatively low metabolic needs but during exercise as the muscles perform work their metabolic requirements increase
• Energy comes in the form of ATP

Question 5

name the energy sources

Answer 5

• immediate energy system
• anaerobic glycolysis
• aerobic

Question 6

describe energy sources

Answer 6

Immediate energy system

• fastest supply of ATP (creatine phosphate/phosphocreatine)
• rapid mobilisation of high energy phosphate
• uses no oxygen

anaerobic glycolysis

• can supply ATP when requirements are high
• less efficient at generating ATP
• uses no oxygen

aerobic

• sustained supply of ATP
• uses oxygen

Question 7

what is creatine phosphate catalysed by in order to release ATP

Answer 7

creatine kinase

Question 8

how is ATP generated from anaerobic glycolysis

Answer 8

• ATP is generated from glucose via the glycolytic pathway.

Question 9

describe lactic acid synthesis

Answer 9

• made when excess pyruvate is converted to lactate
• happens by lactate dehydrogenase
• lactic acid build up can cause a drop in the pH and the muscle can begin to fatigue

Question 10

what is the VO2

Answer 10

the rate of oxygen uptake by skeletal muscle

Question 11

how can VO2 be determined

Answer 11

- by the Fick equation 
VO2 = Q x (CaO2-CvO2)
–	Q is the cardiac output of the heart (blood flow to muscle)
–	CaO2 is the arterial oxygen content
–	CvO2 is the venous oxygen content

Question 12

what is CaO2-CvO2

Answer 12

CaO2 – CvO2) is also known as the arteriovenous oxygen difference.
– Difference between what is going into the capillary bed versus (in terms of arterial oxygen) what is being removed (in terms of venous)

Question 13

what should the VO2 be at rest

Answer 13

• VO2: 250ml/min (70kg person) (oxygen consumption)

- 3.6 ml O2 consumed/min for each kg of body mass (ml O2/(min x kg).

Question 14

define the maximal oxygen uptake

Answer 14

VO2 max is the highest peak oxygen uptake that an individual can obtain during dynamic exercise using large muscle groups during a few minutes performed under normal conditions at sea level. – this is when you are performing maximally at a constant rate

Question 15

what is VO2 max reached

Answer 15

• VO2 max is reached when oxygen consumption remains at steady state despite an increase in workload.

Question 16

what does the VO2 max reflect

Answer 16

• it reflects the aerobic physical fitness of the individual
• important in determinant of their endurance capacity during prolonged, sub-maximal exercise

Question 17

what is the VO2 max in

• COPD/advanced heart disease
• mildy active middle aged adults
• elite endurance athletes

Answer 17

• 10-20 ml o2/(minxkg)
• 30-40 ml O2/(min x kg)
• 80-90 ml O2/(min x kg)

Question 18

what is the anaerobic threshold

Answer 18

• The anaerobic threshold (also known as the lactate threshold) is the point where lactate (lactic acid) begins to accumulate in the bloodstream.

Question 19

what happens in the anaerobic threshold

Answer 19

• Lactic acid is produced faster than it can be metabolized, the development of metabolic acidosis occurs and exercise endurance is reduced.

Question 20

how does the anaerobic threshold vary

Answer 20

• The AT measurements vary from person to person, and, within a given individual, sport to sport.
• Untrained individuals have a low AT whilst elite endurance athletes have a high AT.

Question 21

what are the aims of adjustments of the cardiovascular system that accompany exercise

Answer 21

• Aim of the adjustments during exercise the muscles are actively working and you need to increase oxygen delivery to these muscles
• As well as remove carbon dioxide

Question 22

what are the two major changes in the cardiovascular system as a result of increased exercise

Answer 22

1. Rise in cardiac output – through increases in SV and HR

2. Redistribution of larger proportion of cardiac output to the active muscles

Question 23

how does a rise in cardiac output happen when you start exercise

Answer 23

• Heart rate is kept low by the action of the parasympathetic nervous system (vagus nerve)
• Partial vasoconstriction of blood vessels by activity of sympathetic nerves.
• As exercise begins there is reduced activity of parasympathetic and increased activity of sympathetic nerves.
• Increased HR and mobilisation of blood from great veins (vasoconstriction)

Question 24

what are the cardiovascular changes in exercise due to an increase in sympathetic activity

Answer 24

• Increased venous return
• Increased end diastolic volume (EDV) (increased preload)
• According to Starlings law, increased SV
• Sympathetic activity has a positive inotropic response on the heart.
• The increase in HR and SV act to increase cardiac output during exercise.

Question 25

what increases CO the most in exercise

Answer 25

- In mild exercise small changes in CO are achieved largely by changes in heart rate and stroke volume - Stroke volume reaches maximum levels at fairly moderate exercise intestate - Further increases in CO during heavy exercise are achieved via heart rate changes - During heavy maximal exercise the increase is achieved by heart rate as stroke volume can be limiting

Question 26

what are the long term changes of exercise

Answer 26

- heart remodelling

Question 27

what are the ways in which hypertrophy can happen

Answer 27

hypertrophy can either happen via physiologically such as pregnancy or exercise, or pathologically in diseases such as hypertension

Question 28

what happens to the heart during exercise

Answer 28

- The heart can adapt to sustained increases in blood pressure by increasing muscle mass largely via an increase in cardiac myocytes size (hypertrophy)

Question 29

describe the difference between the athletes heart and the failing heart

Answer 29

THE ATHLETE’S HEART • Increased muscle mass • Normal cardiac function • Reversible ``` THE FAILING HEART • Increased muscle mass • Reduced cardiac function • Irreversible • Cell death and fibrosis ```

Question 30

describe why athletes have bradycardia

Answer 30

- Volume induced cardiac hypetrophy in atheletes increases resting end diastolic volume (EDV) and SV - therefore Athletes typically have a slower resting HR (bradycardia) when compared to untrained individuals

Question 31

Why are cardiac overloading stimuli (e.g. those experienced during exercise) beneficial whilst others are harmful

Answer 31

- could it be because of different signaling pathways

Question 32

describe the redistribution of CO to active muscles

Answer 32

- At rest 20-25% of the resting cardiac output is distributed to the skeletal muscles at about 1 l/min. - During maximal exercise about 80-90% of the increased cardiac output goes to the skeletal muscle with a blood flow of about 22 l/min.

Question 33

what are the two main mechanisms that control redistribution of blood flow

Answer 33

- Systemic regulation | - Local control

Question 34

how does systemic regulation control the redistribution of blood flow

Answer 34

- At the start of exercise there is an increase in the sympathetic outflow to the heart and systemic resistance vessels. - Adrenergic receptors (adrenoceptors) play an important role directing blood flow from non-essential organs to skeletal muscle. - via alpha adrenorecepotrs, beta 1 and 2 adrenoreceptors

Question 35

what do alpha adrenoreceptors do

Answer 35

• Alpha adrenoreceptors constrict the vessels in the gut and cause vasoconstriction of veins.

Question 36

what do beta 1 adrenoreceptors do

Answer 36

• Beta 1 adrenoreceptors (found in the heart) act to increase the rate and force of myocardial contraction

Question 37

what do beta 2 adrenoreceptors do

Answer 37

• Beta 2 adrenoreceptors act to relax smooth muscle and increase ventilation and oxygen uptake and cause vasodilation of blood vessels, especially those supplying skeletal muscle

Question 38

how is blood flow locally regulated

Answer 38

- Blood flow is strongly determined by local regulatory factors either from the blood vessels themselves (endothelial factors and myogenic mechanisms) or from the surrounding tissues (tissue factors).

Question 39

name the endothelial/myogenic mechanisms that help control blood flow locally

Answer 39

- Endothelial/myogenic mechanisms: Nitric oxide acts to relax smooth muscle cells and this causes dilation of blood vessels

Question 40

name the tissue factors mechanism that help control blood flow locally

Answer 40

- Tissue factors: include adenosine and inorganic phosphates, carbon dioxide, hydrogen ions (H+) and potassium ions (K+) released from contracting muscles.

Question 41

describe how blood flow to the skin changes

Answer 41

– vasodilation at the skin initially during exercise so it increases initially during light exercises and strenuous exercises but decreases during maximal exercise, - blood flow to the skin is diverted to skeletal muscles in expense to blood flow to the skin, this means you have not got good thermoregulation

Question 42

how does total peripheral resistance TPR change during exercise

Answer 42

• Total peripheral resistance (TPR) during maximal dynamic exercise drops dramatically – it is approximately one-third of the resting resistance.

Question 43

how do you work out MAP

Answer 43

• MAP = (CO x TPR) + CVP

Question 44

if the TPR decreases why is MABP only slightly increased or normal

Answer 44

* Decreases in TPR are offset by increases in CO | * MABP only rises slightly

Question 45

describe how systolic and diastolic pressure changes

Answer 45

* Increased force of ventricular contraction (increased SV) causes an increase in systolic pressure. * In dynamic exercise the diastolic pressure remains relatively stable or even decreases. * Decrease in the TPR can lead to a decrease diastolic pressure.

Question 46

how does the respiratory system adjust for exercise

Answer 46

- increased pulmonary minute ventilation | - increased oxygen extraction in tissues

Question 47

how does ventilation change in exercise

Answer 47

- At rest pulmonary ventilation is about 8l/min but in heavy exercise can increase to 100 l/min or more - Increased in ventilation is achieved via a rise in respiratory rate and tidal volume (increase in minute ventilation) - At moderate work rates the steady state ventilation is directly proportional to the work done as measured by the oxygen consumption - However during severe exercise the increase in ventilation is disproportionately large in relation to oxygen uptake (limiting factor

Question 48

how is ventilation increased in exercise

Answer 48

- achieved by a rise in respiratory rate and tidal volume( due to increase in minute ventilation)

Question 49

what is the pathway of oxygen uptake from the atmosphere to the mitochondria during exercise

Answer 49

- Uptake of O2 in lungs - pulmonary ventilation - Delivery of O2 to muscle - blood flow and O2 content - Extraction of O2 from blood - delivery and PO2 gradient between blood/cell/mitochondria

Question 50

how does the blood gases change in oxygen

Answer 50

- At high levels of exercise the partial pressure of oxygen in the arterial blood declines slightly - As the oxygen consumption rises the partial pressure of oxygen in the mixed venous blood also declines - The partial pressure of carbon dioxide rises - Overall the arteriovenous difference in oxygen content rises markedly - The increase in gradient drives oxygen diffusion into the cells

Question 51

define the term post exercise oxygen consumption

Answer 51

- There is a measurable increase in the rate of oxygen intake/uptake following strenuous activity (excess post-exercise oxygen consumption (EPOC).

Question 52

describe oxygen consumption during exercise

Answer 52

- Oxygen consumption does not rise immediately to match the energy requirements, it rises progressively over several minutes until it matches a stead state of the needs of the exercising muscles - As the work continues the oxygen uptake remains at a level that is appropriate to the degree of exercise - Thus at the beginning of exercise the body builds up on an oxygen deficit

Question 53

what happens at the end of exercise to oxygen consumption

Answer 53

- At the end of the exercise period the oxygen consumption declines rapidly but may not reach resting levels for up to 60 minutes - There is a measurable increase in the rate of oxygen intake following strenuous activity (excess post-exercise oxygen consumption (EPOC)) proposed to be necessary to eliminate the "oxygen debt." - During the initial phase of oxygen decline ATP and creatine phosphate are resynthesised (via oxidative pathways). Excess lactate is resynthesised into glucose and glycogen.

Question 54

what is the challenge of matching cardiac output and ventilation to the metabolic demands of exercise

Answer 54

- The primary site for coordination/integration is the brain central controller/command with input from sensors

Question 55

what are the factors that regulate the cardiovascular response to exercise

Answer 55

- As exercise begins HR increases and force of contraction increases - Initially changes due to autonomic factors (inhibitor of parasympathetic and increase in sympathetic) - Changes are through to be due to signals from higher brain levels (central command)

Question 56

what does central command receive feedback from

Answer 56

* Central command acts to modulate baroreceptor reflex sensitivity. – the set point changes slightly * Central command also receives feedback from increased activity in afferent nerves from exercising limbs.

Question 57

what do metabaroreceptors respond to

Answer 57

• Metaboreceptors respond to changes in metabolite concentrations (mainly pH and K+) – these are stimulated by metabolites in the skeletal muscle, these feedback information about what is going on during exercise

Question 58

what is the major drive fro ventilation

Answer 58

• Chemoreception also contributes. CO2 major driver for ventilation

Question 59

what do patients with denervated carotid bodies have

Answer 59

• Patients with denervated carotid bodies have slower ventilatory responses compared to normal subjects. Therefore the response of the peripheral chemoreceptors also involved.

Question 60

what provides extra stimulus to the peripheral chemoreceptors

Answer 60

• Plasma potassium concentrations are elevated during exercise and are thorugh to provide an extra stimulus to the peripheral chemoreceptors

Question 61

during exercise there is increased neural input from..

Answer 61

• Increased neural input from afferent activity in the joints