Heat: Signs, Symptoms, and Strategies for Training in the Heat

Keeping athletes and clients performing at their peak while also avoiding heat-related illnesses takes preparation and planning. Bodies need time to adapt to the increased physiological demands of training in warm environments. But even with preparation and planning, heat illnesses can and still do occur.


Heat illnesses generally affect those with lower levels of fitness. More fit individuals are typically better able to tolerate exercising in the heat, acclimate quicker, and sweat more (1). To help clients and athletes meet the demands of training in the heat, acclimate them to the warmer environment over a 10 to 14 day period, balancing the length of training sessions with intensity (i.e., long duration with a low intensity, or short duration with a moderate intensity)(1). Adequate hydration is another key component to preventing heat illnesses, as inadequate hydration decreases the body’s sweat rate. Encourage replacing fluids lost to sweat and urination, and offer hydration breaks during training (1-2). (Contrary to Coach Boone’s words in the iconic football movie “Remember the Titans”, water is not for cowards nor does it make you weak.) Teach participants strategies for monitoring fluid loss, such as daily weigh-ins, and pre- and post-workout weigh-ins if necessary (1-2).

Evaporation of sweat is the body’s key mechanism for staying cool. Humidity decreases the rate of sweat evaporation, as can limiting the skin’s exposure when wearing full training gear. If possible, reduce the amount of gear and clothing worn, especially during the acclimation period (1-2). Selecting moisture wicking fabrics will speed the rate of evaporation over less permeable materials. Also attempt to schedule trainings during the cooler times of the day, either in the early morning or early evening, or move them into climate controlled indoor venues when available.

Heat can also affect children differently, since they have immature thermoregulatory systems, including both a delayed response and limited ability to sweat (3). They may require a longer timeline to acclimate, incorporation of more rest breaks, extended warm-ups and cool-downs, and frequent reminders to hydrate (1-3).

By Stacey Penney NASM-CPT, CES, PES, FNS