ABSTRACT
Potassium metabolism in young adult men exercising in the heat for six consecutive days and the effect of potassium deficiency in mice and rats induced by low potassium diet during heat exposure were observed. Increased potassium loss in sweat and lower potassium intake resulted in negative potassium balance. Individuals with a negative potassium balance had lower se- rum potassium levels and higher body temperature after exercise. Potassium deficient mice accomplished less work done (2.372 vs 4.253 Kg.M) but exih-ibited a markedly greater rate of heat gain (1.36 vs 0.87℃/Kg.M) as compared to the controls. The survival rate and cellular energy metabolism also decreasedThese observations suggest that prevention from potassium deficiency must be emphasized during prolonged physical activity under hot environments. According to the linear regression equations between potassium intake and balance, it is proposed that the potassium requirements in mild and medium physical activity in the heat are 40 and 60 mEq/day respectively, and the allowance of potassium in the latter may be 70-80 mEq/day.