Week 8 - Thermoregulation, Immune System & Altitude

Question 1

What is the normal resting temperature in humans

Answer 1

36.5-37.5C

Question 2

What is the definition of core temperature

Answer 2

Temperature of the hypothalamus, the thermoregulatory centre of the body

Question 3

What are some ways to assess core temperature

Answer 3

Oesophageal temperature
Rectal temperature
Stomach temperature
Oral temperature
Tympanic temperature

Question 4

How does heat affect exercise performance

Answer 4

Increased demand on heat loss mechanisms
Increased dehydration and therefore plasma volume, which disturbs maximal oxygen uptake, muscle strength and work capacity

Question 5

What is the best way to lower body temperature

Answer 5

Cold water immersion is the most rapid way to lower body temperature

Question 6

What are some steps to mitigate the impact of heat stress

Answer 6

Heat acclimation and aerobic training
Pre-cooling, hydration status
Hydration, clothing, cooling

Question 7

What occurs when heat acclimatisation is considered

Answer 7

Improved cutaneous blood flow
Effective distribution of cardiac output
Lowered threshold for start of sweating
Increased swear output
Lowered salt concentration of sweat
Lower skin and core temperatures and heart rate for standard exercise
Less reliance on carbohydrate catabolism during exercise

Question 8

What is hypothermia

Answer 8

Cold stress (core temperature below 35C)

Question 9

What are some physiological effects when exercising in the cold

Answer 9

Greater heat loss
Increased sympathetic stimulation
Peripheral vasoconstriction
Reduced blod flow to adipocytes
Increased carbohydrate metabolism
Increased central blood volume
Increased sympathetic stimulation

Question 10

Physiological adaptations to exercise in the cold

Answer 10

Cold acclimatisation
Results in lower skin temperature at which shivering begins
Maintains higher hand and foot temperature
Improved ability to sleep in cold

Question 11

What effect does altitude have on athletic performance

Answer 11

Lower air resistance may improve performance
Lower PO2 at altitude should have no effect on performance
Lower PO2 results in poor aerobic performance

Question 12

Define the terms Hypoxia, Normoxia, Hyperoxia and Hypoxaemia

Answer 12

Hypoxia: Low PO2
Normoxia : Normal PO2
Hyperoxia: High PO2
Hypoxaemia: Low levels of oxygen in the blood

Question 13

What effect does altitude have on physiological responses during exercise

Answer 13

Partial pressure of O2 is reduced
VO2 max reduced
Ventilation higher (as less number of O2)
Heart rate and cardiac output higher (lower O2 content)
Maximal heart rate lower (parasympathetic activation)
a-vO2 difference decreased (short-term)

Question 14

What are some longer-term adjustments to altitude hypoxia

Answer 14

Pulmonary acid-base
1. Hyperventilation
2. Excretion of base via kidneys
Haemtologic
1. Decreased plasma volume
2. Increased haematocrit, haemoglobin and RBC number
Cardiovascular
1. Heart rate increased
2. Stroke volume decreased
3. Cardiac output unchanged
4. Maximal cardiac output decreased
Local
1. Increased skeletal muscle capillarisation
2. Increased RBC
3. Increased mitochondria density
4. Increased oxidative enzyme activity
5. Loss of body weight and lean body mass

Question 15

What are some benefits and detriments to high altitude training

Answer 15

Benefits: Blood changes (red cell mass), some cellular changes, some circulatory changes

Detriments: Blood changes (viscosity), cardiovascular changes, loss of training intensity, reduced muscle mass, increased ventilatory response

Question 16

Explain the live high, train low strategy

Answer 16

Living at high altitude may elicit increase in red blood cell mass
Train at low altitude to maintain high interval training velocity

Question 17

What are the main physiological thermoregulatory responses

Answer 17

Skin blood flow
Sweating
Shivering
Behavioural responses are our most powerful means of regulating body temp

Question 18

Why is prolonged-high intensity exercise be impaired by a hot environment

Answer 18

Competing regulatory of demand of blood flow between mechanisms such as thermoregulation, working muscle, and CNS

Heat related changes in skeletal muscle function and metabolism

Question 19

What are some short adjustments to altitude

Answer 19

Increasing O2 molecules uptake
Hyperventilation
Raises alveolar O2
Lowers alveolar CO2
Causes alkalosis and diuresis
Increased resting HR and cardiac output

Question 20

How can exercise performance be influenced under heated conditions

Answer 20

Heat stimulates dehydration thus decreases heat loss mechanisms.
Decreases sweat rate and plasma volume
Further decreases cardiac output, oxygen uptake, muscle strength and work capacity

Question 21

What is the effect of Live high train low

Answer 21

Living at high altitude may elicit red blood cell mass
Training low can maintain high intensity trianing velocity

However does not show to have effect on haemoglobin mass, VO2 max, time trial performance, or economy