In The News

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Overview. Physiology of Heat StressCausal factorsHeat Disorders

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In The News

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1. In The News Dealing With Heat Emergencies

2. Overview Physiology of Heat Stress Causal factors Heat Disorders & Health Effects Work-load assessment Control Today we will coverToday we will cover

3. Physiology of Heat Stress Body’s normal set point of thermoregulation is 98.6 F Regardless of activity level, etc.

4. Physiology of Heat Stress Increased ambient temperature and exercise/activity raise the core temperature Heated blood is diverted to the skin where the limbs serve as a radiator to dissipate some heat if ambient air temp < skin temp If rate exceeds capacity, sweat is released to pull away additional heat

5. Physiology of Heat Stress During periods of heavy exertion, it is not uncommon for an athlete to sweat out 1-2L fluid per hour (2.2-4.4 pounds!) After 2-3 hours of exercise Hot Thirsty Fatigued

6. Physiology of Heat Stress Decreased blood volume due to evaporation means increased blood viscosity and decreased availability of blood to be cooled at the skin surface

7. Physiology of Heat Stress Without intervention in the form of rehydration/fluid intake, rest, and/or transfer to cool environment, severity and gravity of heat illness will increase

8. Age, weight, degree of physical fitness Degree of acclimatization, metabolism Use of alcohol or drugs, and a variety of medical conditions such as hypertension all affect a person's sensitivity to heat Causal Factors

9. Causal Factors The type of clothing worn must be considered Prior heat injury predisposes an individual to additional injury.

10. Heat Disorders & Health Effects Heat Stroke Heat Exhaustion Heat Cramps Heat Collapse Heat Rashes Heat Fatigue

11. Heat Stroke Occurs when the body's system of temperature regulation fails and body temperature rises to critical levels This condition is caused by a combination of highly variable factors, and its occurrence is difficult to predict Heat stroke is a medical emergency

12. Heat Stroke - Primary Signs & Symptoms Confusion; irrational behavior; loss of consciousness; convulsions Lack of sweating (usually); hot, dry skin; and an abnormally high body temperature, e.g., an internal temperature of 105.8°F If body temperature is too high, it causes death

13. Heat Stroke - Treatment Professional medical treatment should be obtained immediately. Patient should be placed in a shady area and the outer clothing should be removed. Patient's skin should be wetted and air movement around the worker should be increased to improve evaporative cooling until professional methods of cooling are initiated and the seriousness of the condition can be assessed. Fluids should be replaced as soon as possible

14. Heat Exhaustion Signs and symptoms Headache, nausea, vertigo, weakness, thirst, and giddiness

15. Heat exhaustion - Treatment Removed from the hot environment and given fluid replacement Encouraged to rest

16. Heat exhaustion - Concerns Heat exhaustion should not be dismissed lightly for several reasons Victim may be injured when he or she faints

17. Heat Cramps Caused by performing hard physical labor in a hot environment. These cramps have been attributed to an electrolyte imbalance caused by sweating It is important to understand that cramps can be caused by both too much and too little salt

18. Heat Cramps Thirst cannot be relied on as a guide to the need for water; instead, water must be taken every 15 to 20 minutes in hot environments

19. Heat cramps - Treatment Under extreme conditions, such as working for 6 to 8 hours in heavy protective gear, a loss of sodium may occur (hyponatremia) Recent studies have shown that drinking commercially available carbohydrate-electrolyte replacement liquids is effective in minimizing physiological disturbances during recovery

20. Heat collapse "Fainting" In heat collapse, the brain does not receive enough oxygen because blood pools in the extremities The onset of heat collapse is rapid and unpredictable

21. Heat Rashes Most common problem in hot environments Prickly heat is manifested as red papules and usually appears in areas where the clothing is restrictive

22. Heat Rashes Prickly heat occurs in skin that is persistently wetted by unevaporated sweat, Heat rash papules may become infected if they are not treated In most cases, heat rashes will disappear when the affected individual returns to a cool environment.

23. Heat Fatigue A factor that predisposes an individual to heat fatigue is lack of acclimatization Signs and symptoms include impaired performance of skilled sensorimotor, or mental function Best treatment is to remove heat stress before a more serious heat-related condition develops

24. On average, about 175 Americans succumb to the taxing demands of heat every year. Our bodies dissipate heat by varying the rate and depth of blood circulation, by losing water through the skin and sweat glands, and as a last resort, by panting, when blood is heated above 98.6°F. Sweating cools the body through evaporation. However, high relative humidity retards evaporation, robbing the body of its ability to cool itself. When heat gain exceeds the level the body can remove, body temperature begins to rise, and heat related illnesses and disorders may develop. The Heat Index (HI) is the temperature the body feels when heat and humidity are combined. The chart below shows the HI that corresponds to the actual air temperature and relative humidity. (This chart is based upon shady, light wind conditions. Exposure to direct sunlight can increase the HI by up to 15°F.) (Due to the nature On average, about 175 Americans succumb to the taxing demands of heat every year. Our bodies dissipate heat by varying the rate and depth of blood circulation, by losing water through the skin and sweat glands, and as a last resort, by panting, when blood is heated above 98.6°F. Sweating cools the body through evaporation. However, high relative humidity retards evaporation, robbing the body of its ability to cool itself. When heat gain exceeds the level the body can remove, body temperature begins to rise, and heat related illnesses and disorders may develop. The Heat Index (HI) is the temperature the body feels when heat and humidity are combined. The chart below shows the HI that corresponds to the actual air temperature and relative humidity. (This chart is based upon shady, light wind conditions. Exposure to direct sunlight can increase the HI by up to 15°F.) (Due to the nature

25. Heat Hurts Performance at Best…Kills at Worst!

26. High Profile Heat Related Deaths Korey Stringer Minnesota Vikings OL 27 years old 335 pounds Collapsed of heatstroke during fall camp; died 15 hours later

27. High Profile Heat Related Deaths Eraste Autin University of Florida freshman fullback 6’2”, 250 pounds 88 degrees, 72% humidity on the day he collapsed during a routine training session Core temp > 108 degrees

28. Monitoring Heat: Cutting Edge Technology CorTemp ingestible sensors developed by NASA allow ATs to monitor core temp wirelessly Stay within system 18-30 hours Passed painlessly Can monitor entire team from a wireless PDA or laptop

29. Exam 2 Exam format 30 multiple choice/true false (2 points each) 40 points worth of short answer/essay Content Strength & Conditioning Pharmacology Environmental Conditions Heat Emergencies

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