Environmental exercise physiology

Question 1

Body temperature regulation: Transfer of body heat

Answer 1

1. Conduction: heat transfer through direct molecular contact from one solid material to another. Sitting on chilly or hot metal bleachers
2. Heat transfer by the movement of gas or liquid across a surface
   - increase movement across skin surface: increase heat exchange
   Major daily thermoregulatory factor
3. Radiation: Heat loss in the form of infrared rays. The body is able to give off or receive radiant heat. Major daily thermoregulatory factor
4. Evaporation: Heat loss via phase change from liquid to gas. Primary heat loss during exercise (80%). Clothing= resistance to E
5. Humidity and Heat loss= E affected by water vapour pressure (Humidity)
   - Increase of humidity, decrease of Evaporation and increase of evaporation
   - prolonged evaporation via sweat = dehydration.

Question 2

Effects of acclimation

Answer 2

• CDV function optimized
• Changes in sweating rate, sweat distribution and sweat content
• Lower core temperature during exercise
• repeated exercise in the heat: rapid changes for better performance in hot conditions. Short term (9-14 days)

Question 3

Exercise in the heat: Health risks

Answer 3

1. Heat cramps
   - least serious of the heat illness
   - Severe, painful cramping of large muscles
   - Triggered by NA+ losses, dehydration
   - Most common in heavy sweaters
   - Prevented by the liberal intake of NA+, water
2. Heat exhaustion
   - Fatigue, dizziness; nausea; vomiting, fainting- weak, rapid pulse
   - Caused by severe dehydration from sweating
   - Simultaneous blood flow needs of muscle and skin not met due to low BV
   - Thermoregulatory mechanisms are functional but overwhelmed
3. Heat stroke
   - Life-threatening, most dangerous
   - Thermoregulatory mechanism failure
   - characterised by:
   - core temp > 40 degrees
   - confusion, disorientation, unconscious
   - If untreated: coma/death
   - Whole body cooling ASAP

Question 4

Dehydration effects

Answer 4

• reduction in sweat rate of skin blood flow
• increased HR
• Small reduction in BV and BP
• Large reductions in SV and CO
• Reduced blood flow to active and inactive muscles, skin, brain

Question 5

Exercise in the cold

Answer 5

• Cold habituation: After repeated exposures with no significant heat loss VC, shivering blunted; core temp allowed to decrease more.
• Metabolic acclimation: After repeated exposures with heat loss. Enhanced metabolic, shivering heat production
• Insulative acclimation: When metabolism increases cannot prevent heat loss. Enhanced skin VC

Question 6

Altitude

Answer 6

• Low altitude (500-2000m)
  Does not affect the wellbeing
  performance may be decreased
• Moderate altitude (2000-3000m)
  Affect well-being in unacclimated people
  Performance decreases
• High altitude (3000-5000m)
  Acute mountain sickness
  performance decreases
• Extreme high altitude (>5500m)
  severe hypoxic effects
• For our purposes
• Few physiological effect

Question 7

Hormonal responses

Answer 7

Immediate onset of exercise
- increase norepinephrine
- Increase of Epinephrine
- Increase of glucagon
- a decrease of insulin
- Increase in Cortisol
- Increase of cell insulin sensitivity
- Increase of Glut-4 intracellular transporter activity
All these: Glycogenolysis and glycolysis in the liver and muscle. Increased glucose uptake into exercising muscle
Increased FFA mobilisation and uptake. Increased availability of glucose to fuel exercise. Increased cardiac work.

Question 8

Hormonal responses 2

Answer 8

• Aldosterone (>30 min)
• Antidiuretic hormone (>30 min)
• PYY; GLP-1 (vigorous)
  all these: sodium spring, water sparing (>15 min). Prevent dehydration