Exercise in Heat

Question 1

what are the four mechanisms to regulate core temperature

Answer 1

1. radiation
2. conduction
3. convection
4. evaporation

Question 2

describe radiation as a mechanism to regulate core temperature

Answer 2

Transfer of heart by electromagnetic waves

Question 3

describe conduction as a mechanism to regulate core temperature

Answer 3

Transfer of heat through direct contact

Question 4

describe convection as a mechanism to regulate core temperature

Answer 4

Transfer of heat by the motion of moving substances (typically air or water)

Question 5

describe evaporation as a mechanism to regulate core temperature

Answer 5

Transfer of heat resulting from the evaporation of water (sweat) on the skin surface

Question 6

describe what sweat is

Answer 6

Sweat is the primary mechanism by which heat can be dissipated from the body

Question 7

list five physiological changes due to heat

Answer 7

1. increased core temperature
2. increased heart rate
3. increase in sweating
4. increased blood viscosity
5. increased peripheral blood flow

Question 8

describe increased core temperature as a physiological response to heat

Answer 8

The core temperature increases due to the outside temperature and body’s metabolism while exercising.

Question 9

describe increased heart rate as a physiological response to heat

Answer 9

An increase in heart rate is due to the body’s increased temperature which means blood must go to the skin to allow heat loss as well as muscles to continue exercising.

Question 10

describe increased sweating as a physiological response to heat

Answer 10

Increased sweating is due to the body losing heat through evaporation.

Question 11

describe increased peripheral blood flow as a physiological response to heat

Answer 11

Increased peripheral blood flow is due to blood being redirected to the skin to dissipate heat through convection.

Question 12

describe increased blood viscosity as a physiological response to heat

Answer 12

Blood viscosity is a measure of the resistance of blood to flow. Therefore an increase in blood viscosity will make the blood more thick and more sticky.

Question 13

what happens when exercising in heat

Answer 13

A significant amount of body fluid is lost via sweat. A loss of fluid equal to 1-2% of body mass during exercise will impair both athlete performance and mental function

Question 14

what are three pre-event hydration strategies

Answer 14

1. Adequate hydration is crucial prior to exercise in the heat (200 - 600ml)
2. The amount of water intake required to achieve adequate hydration will vary between individuals
3. Hyperhydration is the consumption of excess fluid in preparation for loss of fluid in upcoming exercise

Question 15

what are four hydration strategies to do during exercise

Answer 15

1. drinking during exercise (400 - 800ml per hour) will decrease the risk of dehydration
2. For short-duration events aim to drink 100 - 200ml per 15 minutes
3. Drinking plain water is adequate for exercise less than one hour in duration
4. For exercise less than one hour, combining carbohydrates with fluid is beneficial

Question 16

list three strategies for coping with exercise in the heat

Answer 16

1. wear thin, light-coloured cotton clothing
2. pre-cooling strategies to lower the core body temp prior to exercise
3. cooling strategies during the event

Question 17

why should someone wear less clothing

Answer 17

The less clothing the better to allow skin exposure for evaporative cooling

Question 18

what are some pre-cooling strategies someone could use

Answer 18

ingesting slushies and wearing a ice vest

Question 19

why and what are some cooling strategies during the event

Answer 19

This lowers the core body temperature allowing the athletes to continue playing for longer. COuld wear ice vests and sit in shade.

Question 20

what is heat acclimatisation

Answer 20

Involves a period of training (typically 5-10 days) in a hot environment to allow the body to prepare to perform in a similar environment which is expected for competition

Question 21

what are five chronic adaptations to successful heat acclimatisation?

Answer 21

1. increased sweat rate to optimise evaporative cooling
2. Decrease core temperature means that you are further away from the limiting temperature
3. Increased blood plasma increases cardiac output to allow more effective evaporative cooling and oxygen delivery to muscles
4. lower vasodilation thresholds increase skin blood flow address heat loss mechanisms earlier, and delays the subsequent rise in temperature
5. early onset of sweating delayed subsequent rise in the body temperature

Question 22

what is humadity

Answer 22

Humidity represents the proportion of water in ambient air. If the relative humidity is high there is nowhere for the sweat on the skin to evaporate.

Question 23

what does humidity do to the body? what does it cause?

Answer 23

Humidity places greater stress on the body. It limits the body’s ability to lose heat via evaporation making it more difficult to exercise in the heat, placing athletes at a greater risk of overheating.