at_environment

Environmental Considerations

HYPERTHERMIA (Elevated body temperature)
Heat stress
- Metabolic heat production
- Conductive heat exchange
- Convective heat exchange
- Radiant heat exchange
- Evaporative heat loss
    o Ability to dissipate heat by evaporation is severely limited in hot, humid environment because evaporation
       cannot occur unless volumes of dry air are available to absorb the water vapor given off
Monitoring the Heat Index
   WBGT (wet bulb globe temperature) index measures heat and humidity
   WBGT = (0.7 Twb) + (0.2 Tg) + (0.1 Tdb)
   - ACSM (The American College Sports Medicine) recommend road races be rescheduled based on 82º F
Heat illnesses
Heat Rash (prickly heat)
   - Wear loose fitting clothes and avoid heavy sweating
Heat Syncope (heat collapse)
Heat Cramps
   - Imbalance between water and electrolytes
Heat Exhaustion
   - Dehydration
   - Mildly elevated temperature (102º F)
Heat Stroke
   - Life threatening emergency
   - 106º F or higher
   - May cause death

   - Heat-related illness is most likely to occur in non-acclimatized athletes by salt-depletion heat exhaustion
   - An extreme endomorph somatotype is more prone to heat-related illness
     (The ponderal index is used to determine somatotype)
   - Obese athletes or athletes with a previous history of heat illness are risky.
   - Artifitial turf can be watered to reduce injuries, but heat illness is likely to increase with high humidity
   - Rebberized sweat suits contribute to heat illnesses

Preventing Heat Illness
   - Fluid and Electrolyte Replacement (Rehydrate during activity is best way!!)
     o 1.5~2.5 liter/hr (Average runner)
     o 5% glucose solution
     o Thirst will replace 50% of fluid lost during a hot day
   - Gradual Acclimatization (about two weeks)
   - Identification of susceptible individuals
   - Lightweight uniforms (Short sleeve T-shirts, shorts, and short socks)
   - Routine weight record keeping (3~5 % weight loss)
   - Unrestricted fluid replacement
   - Well-balance diet
   - Routine temperature and humidity readings
   - A cold shower before a workout will help an athlete resist heat and keep the body cool
   - ACSM recommends distance running - before 8 AM/ after 6 PM in summer
   - Distance race organizer need to disqualify runners if they shows signs of heat injury

HYPOTHERMIA
   - Many sports played in cold weather do not require heavy protective clothing; thus, weather becomes a
     factor in injury susceptibility.
   - A thin, short runner running 8 mph into a 10 mph head wind is most likely to suffer hypothermia
- 75% of heat produced by the body is lost through radiation
    (Vascular area of head and neck = 50% of total heat loss)
- 20% of heat loss is through evaporation (skin: respiratory tract = 2: 1)
- Shivering ceases below a body temperature of 85 to 90º F (29.4 to 32.2º C)
- Death is imminent if core temperature rises to 107º F (41.6º C) or drops to between 77 & 85º (25 and 29º C)
- Air temperature of 30~50 degree F, 80% humidity, and extreme fatigue tend to cause hypothermia
- Reynaud’s syndrome = Numbness or tingling in either or both hands in cold weather,
    o Bilateral episodic spasms of the digital blood vessels. The cause is usually idiopathic

Prevention
- Keep head & neck well-covered in cold weather because greatest loss of heat from body occurs there

Common Cold Injuries
- Frost nip
- Frostbite
    o Rapid re-warming of body part in warm water between 100 and 110º F
    o Re-warming of the body part should continue until it is deep red/bluish in color

ALTITUDE
- Most athletic events are not conducted at high altitudes

Adaptation to Altitude
- Athlete arrive 2~3 weeks before competition provides the best adjustment period

Altitude Illness
- Acute Mountain Sickness
- Pulmonary Edema
    o At altitude of 9,000 to 10,000 feet, high-altitude pulmonary edema may occur
    o Lungs at this altitude will accumulate a small amount of fluid within the alveolar walls
    o Signs of pulmonary edema include acute dyspnea, cough, headache, and weakness
- Sickle Cell Trait Reaction
    o Approximately 8 to 10% of African Americans have the sickle cell trait
    o An abnormal hemoglobin molecules become deoxygenated as a result of exercise at a high altitude, the cells
       tend to clump together
    o Pain in left lower ribs, weakness, nausea, and hematuria
    o Susceptible to an enlarged or ruptured spleen

AIR POLUTION

Ozone
- The ozone levels are most diminished in the later afternoon because of the lower temperatures and decreased
     amount of traffic on the roads

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