Topic 9: Exercise Testing and Perscription Flashcards
State what you understand by the term “VO2max” and summarise its physiological basis.
VO2 max is the aerobic exercise and maximal oxygen uptake. The ability to take up, transport and ultilise O2 by the body provides the main energetic basis for sustained muscular activity
Determines work capacity
Physiological basis:
- ability of cardiorespiratory system to deliver oxygen to muscles
- Ability of muscles to use oxygen and produce ATP aerobically
State the Fick Equation relating whole body O2 uptake to cardiac output and O2 extraction from blood.
VO2 = Q x (CaO2 - CvO2)
CaO2 = amount of O2 in arterial blood CvO2 = content of O2 in mixed venous blood
Oxygen uptake is the product of cardiac output and the arterio-venous oxygen content difference
*** (UNSURE)
For a healthy young (non athlete) male give typical values at rest and during maximal exercise for:
(i) Workload
(ii) O2 consumption
(iii) cardiac output (CO)
(iv) heart rate & stroke volume (v) systolic
diastolic & mean blood pressure
(vi) arteriovenous O2 content difference.
(i) Workload
(ii) O2 consumption
(iii) cardiac output (CO)
(iv) heart rate & stroke volume (v) systolic
diastolic & mean blood pressure
(vi) arteriovenous O2 content difference.
Briefly explain how cardiac output increases substantially on exercise without a large increase in MAP.
During exercise the CO increases more than the total resistance decreases, so the MAP usually increases by a small amount
*** (UNSURE)
For a healthy young (non athlete) male give typical values at rest and during maximal exercise for:
(i) CO2 production
(ii) minute (pulmonary) ventilation
(iii) respiratory rate & tidal volume
(iv) dead
space volume & alveolar ventilation (v) arterial & mixed venous PO2, PCO2 and O2 saturation.
(i) CO2 production
(ii) minute (pulmonary) ventilation
(iii) respiratory rate & tidal volume
(iv) dead
space volume & alveolar ventilation (v) arterial & mixed venous PO2, PCO2 and O2 saturation.
Briefly describe how CO is redistributed to physiological systems to meet demands of heavy exercise
Redistributes the blood so more of it goes to the working muscles and less of it goes to body organs such as the digestive syste,
Briefly describe how CO is redistributed to physiological systems to meet demands of heavy exercise
Redistributes to the working skeletal muscles, increased flow to skin for effective thermoregulation and cerebral blood flow.
Reduced flow to lessa active organs; liver, kidneys, GI tract.
In connection with incremental exercise state what is meant by terms
(a) anaerobic threshold
(b) respiratory compensation threshold. Briefly describe the physiological basis of these events.
(a) anaerobic threshold
As VO2 progressively increases with incremental exercise, a point is reached when anaerobic metabolism is engaged - marked by the appearnace of hydrogen/ions in blood
(b) respiratory compensation threshold
- the point at which the exercise intensity increases and excessive CO2 excretion by respiratory compensation begins due to accumulation of H+ ions
(H+ can no longer be buffered and blood pH falls)
Identify the efferent neural pathways that lead to the increased
(a) cardiac muscle and
(b) respiratory muscle activity during exercise.
(a) cardiac muscle
- sympathetic pathway
(b) respiratory muscle activity during exercise.
- by increasing the rate and intentsity of motor neurone activity in nerves innervating respiratory muscles
Identify the primary factors that lead to an increase in stroke volume during exercise.
Increased ventricular contractility, from increased ejection fraction adn madiated by sympathetic nerves to the ventricular myocardium
Identify the primary chemoreceptors and baroreceptors that operate to maintain cardiovascular and
respiratory homeostasis in many situations and explain why these cannot account for the
cardiorespiratory response to exercise.
physiological systems use negative feedback principles to maintain homeostasis
Briefly explain the concept of a feedforward mechanism to explain the prompt cardiorespiratory
response to exercise and identify (i) higher brain centres (ii) peripheral receptors that may be involved
Since negative feedback mechanisms seem unable to explain the observed breathing and heart rate responses associated with exercise, researchers have proposed that the response may be related to a feed-forward
- hypothalamus
- primary motor cortex
What is cardiac output?
Cardiac Output: the amount of blood pumped by the left ventricle (to whole body) per minute
CO = HR x SV
What is the blood flow distribution of C.O per L/min?
a) at rest
b) vigerous exercise
a) CO = 5.8 L/min
b) CO = 25.6 L/min
• Name 5 medical conditions featured in ISP that can be better managed by prescribing an exercise program’
Asthma
Chronic Heart Failure
COPD
CHD
DMT1
DMT2
Hypertension
Kidney Disease
Stroke
