Exercise physiology

Question 1

Does exercise physiology allow us to predict performance?

Answer 1

No.

The ability to predict performance would likely destroy the industry.

Question 2

What is fatigue?

Answer 2

Failure to maintain the desired power output
Encompasses: ABILITY and WILLINGNESS to perform work
Causes: Peripheral factors, Central factors

Question 3

Peripheral fatigue

Answer 3

Due to factors operating at the muscle cell membrane or in the cytoplasm

Question 4

Central fatigue

Answer 4

Due to processes occuring proximal to the neuromuscular junction

Question 5

VO2

Answer 5

= oxygen uptake
= the rate at which o2 is used by the animal
= cardiac output x O2 removal by tissues

Question 6

VO2 during exercise

Answer 6

increases up to a maximum value = VO2max

VO2max increases as fitness level increases

Question 7

Why does VO2 increase during exercise? (4)

Answer 7

1. Heart rate increases
2. Stroke volume increases
3. Difference in O2 content of arterial blood vs venous blood increases
4. Circulating blood volume increases

Question 8

Relationship between HR and exercise intensity as horse becomes fitter (2)

Answer 8

As horse becomes fitter, at a given submaximal exercise intensity:

1. HR decreases
2. VO2 as % of oxygen uptake max decreases

Question 9

2 major limiting factors of the respiratory system in performance horses

Answer 9

1. Ventilation is locked to gait at the canter and gallop

2. A large increase in cardiac output –> blood travels through lungs very quickly - pressure very high

Question 10

Result of limiting factors of respiratory system in performance horses (2)

Answer 10

1. Hypoxaemia and hypercapnia: not enough O2 can be added and not enough CO is removed
2. Stress failure of pulmonary capillaries (EIPH): high pressure (also genetic predisposure)