exercising in heat/humidity

Question 1

how does themoregulatory system attempt to remove heat from body

Answer 1

Primary goal of the thermoregulatory system during exercise in heat is to remove heat from body
• Sweat glands stimulated to increase sweat production
• Vasodilation occurs @ arterioles of skin to increase blood flow to periphery for cooling
• Fluid loss via sweating = gradual decrease plasma volume

Question 2

what happens when temp exceeds body temp

Answer 2

As temp increases conduction, convection and radiation decrease their effectiveness to facilitate body heat loss. When temp exceeds body temp body gains heat by these 3 methods. In these conditions sweat evaporation from skin and respiratory tract provide only means for heat dissipation

Question 3

what is double heat load

Answer 3

Double heat load – when exercising in heat body forced deal with 2 forms heat: metabolic heat created by working muscles and environmental heat
• This creates comp for blood flow
• Muscles require oxygenated blood to sustain energy production
• Periphery for cooling as blood and core temp rise

Question 4

definition of cardiovascular drift

Answer 4

gradual, time dependent downward drift in number of cardiovascular responses

Question 5

reponses of cardiovascular drift (5)

Answer 5

1. Fluid loss exceeds fluid gain – decrease in blood plasma therefore decrease SV
2. this decreases cardiac output and further strain is placed on comp for blood flow between working muscles for energy and periphery blood vessels for cooling
3. as exercise continues blood is prefereneced to interal organs and working muscles
4. this will decrease periphery blood flow and negatively affect thermoregulatory functions as well as decreased sweat rate
5. core temp increases, aerobic energy production and vo2 max decreases and athlete at risk suffering from heat related illnes as well as significant decrease in perfromance

Question 6

effect of high humidity

Answer 6

With high humity evaporation greatly diminishes (still large amounts of sweat) – this form of sweating represents useless water loss that can prevent dehydration and overheating

Question 7

physiological effects of dehydration

Answer 7

• severely compromises cardiovascular function and exercise capacity
• affects the bodies ability to dissipate heat and therefore increases the rate of heat storage

As dehydration progresses, plasma volume decreases as peripheral blood flow and sweating rate diminish. This;
•	↑ heart rate
•	↑ core temperature
•	↓sweating rate
•	↓ VO2 max
•	↓ blood pressure

Question 8

symptoms of heat illness

Answer 8

• Light headed, nausea, pale
• Reduced/little sweating
• Confusion, altered consciousness, collapse
• Increase core temp

Question 9

what is heat cramps

Answer 9

occur in voluntary muscles several hrs after strenuous exercise in individuals who lost large volume sweat and excreted small volume urine

Question 10

heat acclimatisation

Answer 10

Body’s ability to adapt to repeated daily exposure of exercise in heat to reduce the impact of heat on physiological function and exercise performance

Question 11

Methods used to acclimatise

Answer 11

1. Live and trait in got environment where sporting event held
2. Live and train in another location
3. Stay home simulate hot conditions

Question 12

acclimatisation - frequency

Answer 12

• 7-14 lving and training in heat
• Major adaptations occur within first few days of repeated heat exposure
• Heat acclimatisation should occur daily or at intervals of no more than three days apart for 10 to 12 sessions, otherwise deacclimatisation starts to occur

Question 13

acclimatisation - duration

Answer 13

• Exercise should last60 to 90 minutes either in hot conditions or wearing heavy clothing

Question 14

acclimatisation - conditions

Answer 14

• Exercise in 25-30 degrees celcius (any hotter and the intensity needs to be reduced)
• Wearing heavy clothing in cool conditions- causes the same increased sweating response as with heat exposure

Question 15

chronic adaptations to heat acclimatisation (3)

Answer 15

Sweating – changes optimise cooling and preserve essential electrolytes
• Increases sweat rate
• Early onset of sweating (lower sweqting threshold)
• Effective distribution of sweat
• More dilute sweat
Decrease core temp
• Means further away from limiting temp
Cardiovascular – ensures greater proportion of Q to the msucles
• Decrease HR
• Increase PV
• Lower vasodilation threshold (increase skin blood flow)

Question 16

ways to prevent heat stress (6)

Answer 16

• Acclimatise (train in warm conditions)
• Decrease clothing, increase rest, fans, icepacks, decrease warm ups during exercise
• Avoid hottest part of the day if feasible
• Wear light weight clothing
• Ensure adequate hydration- water, sports drinks, slushies
• Use pre-cooling methods

Question 17

what is pre-cooling

Answer 17

Attempt minimise negative effect of high core temp athletes use pre-cooling methofd to reduce skin and core body temp before comp.

Question 18

examples of pre cooling

Answer 18

• Ice baths or cool pools
• Cold showers
• Ice vests
• Refrigerated cool rooms
• Ventiliation or fans
• Protective shade
• Reduced or modified clothing