Athletes are at risk to certain heat disorders that are created by deficits in body water (Table). These result from failure to replace large or recurrent sweat water losses. These disorders are as follows.
Heat cramps are painful and vigorous muscle contractions that most commonly involve the gastrocnemius or hamstring muscles. These cramps are most common early in the season and affect the underconditioned athlete; they result from inadequate circulation to the exercising muscle. The early season hot weather cramps suffered by athletes are distinctly different than the "miner's cramps" and "stoker's cramps" studied in industrial settings early in this century. Miners and steel factory workers were found to be electrolyte depleted through profuse sweat losses during eight- to 12-hour work periods day after day in hot environments. There is no evidence that the early season hot weather cramps in healthy young athletes are in any way related to electrolyte
Smith NJ, Stanitski CL, Dyment PG, Smith RE, Strong WB. The Prevention of Heat Disorders in Sports. Am J Dis Child. 1984;138(8):786-790. doi:10.1001/archpedi.1984.02140460076025