Beat the Heat

Beat the Heat

Tips for avoiding heat injury when exercising in hot weather

American Council on Exercise Chief Science Officer Dr. Cedric X. Bryant offers up some tips to keep you healthy as temperatures around the country continue to climb.

In excessively warm and often humid conditions, heat stress can be a real threat for individuals who engage in aerobic-type exercise activities — either outdoors or indoors in facilities without air conditioning. Individuals exercising in a warm, humid
environment should adhere to five relatively basic guidelines to avoid heat injury.

• Adequately hydrate. This can be accomplished by consuming copious amounts of fluid (just short of feeling fully bloated) thirty minutes before exercise, drinking at least six ounces of fluid after approximately every 20 minutes of exercise, and drinking beyond thirst cessation during the recovery period. Water is generally considered the best hydration fluid unless the duration of the exercise bout exceeds 60 minutes. If an individual exercises for longer than an hour, a sports drink (e.g., Gatorade or PowerAde) may be the more beneficial.
  
• Become acclimatized to the environment. Acclimatization, the body's gradual adaptation to changes in environment (it usually takes 10-14 days of heat exposurecombined with exercise), can greatly reduce an individual's risk for heat injury. Following
  acclimatization, individuals will sweat sooner, produce more sweat, and lose fewer electrolytes in their sweat. The net effects of acclimatization are a lower body core temperature, a decreased heart rate response to exercise, and a diminished potential for dehydration and electrolyte depletion.
  
• Lower the intensity level. Especially during the acclimatization period, this will decrease the heat load and reduce the strain on thermoregulatory mechanisms.
  
• Never wear clothing that is impermeable to water (e.g., rubberized sweat suits), since such clothing prevents the evaporation of sweat from the skin and thereby increase the risk of heat injury.
  
• Respect the existing environmental conditions since temperature and relative humidity can greatly influence both the degree of heat stress and the body's ability to effectively respond to the heat stress.
  

As a general rule of thumb, an individual should consider curtailing exercise when the ambient temperature is above 90 degrees Fahrenheit and, concurrently, the relative humidity is above 60 percent.