GUNGAHLIN COLLEGE

1. GUNGAHLIN COLLEGE Human Movement SPORTS INJURIES Environmental Injuries

2. Environmental Injuires • Heat Injuries • Cold Injuries • Altitiude

3. Core Body Temperature • 34°C - Hypothermia • 36°C – Minimise heat loss and active heat production • Normal – 36.5°C – 37.5°C • 38°C – Heat loss mechanisms are activated • 41°C – Hyperthermia

4. How can the body lose and gain heat • Evaporation • Heat is lost when sweat on the skin is evaporated  converting liquid to gas • Radiation • Heat can radiate from a warm object to a cooler one. In a cold climate, athletes will radiate heat to the environment surrounding them. During exercise on a warm day, an athlete will gain heat from the surrounding environment

5. Convection • Airflow across the body • Cold, windy conditions increase heat loss • Conduction • Heat is transferred when two objects of different temperatures contact each other

6. How does the body control its temperature? Changing the amount of blood flow to the skin • Hot: blood vessels dilate to increase the blood flow to the skin. • Heat moves to the body surface • More blood committed to transporting heat to the body surface, the less available to the working muscles Sweating • Large quantities of water can be lost as sweat when exercising • Fluid replacement necessary to control temperature and function • Dehydration will limit the body’s ability to sweat and lose heat and therefore diminish performance Shivering • The body will attempt to produce heat by shivering • Appropriate clothing is essential

7. Heat Illness • Heat illness can be categorised into two categories: • Heat exhaustion • Heat stroke • Dehydration - will reduce performance and increase the risk of heat illness. Fluid loss reduces the body’s ability to sweat and therefore its ability to cool itself. • Dehydration will also reduce the blood supply to the skin contributing to an increase in core temperature. • The more intense the activity, the less dehydration can be tolerated by the body before it will effect performance.

8. Factors effecting heat illness - Fluid • Water comprises 50-70% of a person’s body weight. During exercise water can be lost (as sweat) at rates of up to 4-5 litres in a 2-hour period • Thirst is not an adequate indicator of the body’s need for water: • When exercising in the heat, athletes should monitor fluid loss by weighing themselves before and after exercise. Each kilogram of weight lost indicates approximately one litre of water has been lost from the body

9. Factors increasing the risk of heat illness • Hot Environments- hot environments minimize heat loss and may lead to heat gain. • High humidity- humid environments will reduce the body’s ability to lose heat whilst sweating. • Inadequate fluid intake- Inadequate intake of fluids will lead to dehydration and restrict sweat rates which will lessen the body’s heat loss. • Poor fitness- more fit athletes have better heat loss mechanisms that unfit athletes. • Exercise in unaccustomed heat- the body’s ability to lose heat improves after about a two week period of acclimatization period. • Inappropriate clothing- inappropriate clothing may interfere with the air flow and sweating responses necessary to achieve maximum heat loss.

10. HEAT EXHAUSTION • SMA slides 155

11. HEAT STROKE • SMA slides 161

12. Prevention Of Heat Injury The risk of experiencing heat illness, particularly in hot conditions, can be reduced in the following ways:

13. Prevention - The Timing of Games • Where possible, games should not be scheduled during the hottest part of the day • Early morning or night games are preferable • Adjusting training and competition intensity to conditions can reduce risk

14. Athletes • Rest participants during games using player interchange or substitution • Players should rest in shaded areas • Acquiring adequate fitness and acclimatisation • Provide fans, ice packs and ice vests • Provide additional fluids

15. Clothing • Light coloured • Loose fitting • Adequate ventilation • UV protected clothing

16. Hydration - Fluid Replacement • - In the hour before event 1-2 glasses of water (250ml glass) • - During Event 1 glass of water every 15-20 minutes (250 ml glass) • - After event Fluid should be consumed regularly to replace fluid loss. Amounts will depend on the weather conditions. • You should have a comfortable amount of fluid in the stomach when entering the event.

17. Altitude • Levels of Altitude • Low – 0-1500m (Canberra 600m, Thredbo 1300m) • Moderate - 1500-3000m (Mexico City 2300m, Kosciusko 2228m) • High- 3000-5000m (Brady’s joint) • Extreme - >5000m (Everest 8848m) • As altitude increases, there is a decrease in barometric pressure and results in the air becoming less dense. This results in a reduction in the oxygen levels in the blood and muscle tissue. • The most immediate response to altitude by the body is the hyperventilation that results from the decrease in oxygen levels. There is also an increase in the resting heart rate and cardiac output. • With an acute exposure to altitude the body’s cardiovascular capacity (VO2 max) will reduce.

18. Acclimatisation • Participants should be fully acclimatised prior to participation • Particularly during the change of climatic seasons • Special consideration for participants travelling from cool to hot climates

19. Acclimatisation • Adaptations occur over 2-3 weeks • The body will try to adjust to the altitude by secreting a hormone called erythropoietin (EPO), which stimulates the bones to increase the red blood cell production, which in turn enables blood to carry more O2. • This acclimation will begin in the first 24-48 hours of reaching a higher altitude but can take several weeks to complete. • If competing 2-3 weeks is required to acclimatise • Responses to acclimatisation: • Increased plasma volume • Earlier sweating response • More sweating • More dilute sweating (minimises electrolyte loss)