Potassium loading effect on potassium balance in athletes during prolongedrestriction of muscular activity

Negative potassium balance during hypokinesia (decreased number of kilomete rs taken/day) is not based on the potassium shortage in the diet, but on th e impossibility of the body to retain potassium. To assess this hypothesis, we study the effect of potassium loading on athletes during prolonged hypo kinesia (HK). Studies were done during 30 d of a pre-HK period and during 364 d of an HK period. Forty male athletes aged 23-26 yr were chosen as subjects. They wer e divided equally into four groups: unloaded ambulatory control subjects (U ACS), unloaded hypokinetic subjects (UHKS), loaded hypokinetic subjects (LH KS), and loaded ambulatory control subjects (LACS). For the simulation of t he hypokinetic effect, the LHKS and UHKS groups were kept under an average running distance of 1.7 km/d. In the LACS and LHKS groups, potassium loadin g tests were done by administering 95.35 mg KCl per kg body weight. During the pre-HK and HK periods and after KCl loading tests, fecal and uri nary potassium excretion, sodium and chloride excretion, plasma potassium, sodium and chloride concentration, and potassium balance were measured. Pla sma renin activity (PRA) and plasma aldosterone concentration was also meas ured. Negative potassium balance increased significantly (p less than or eq ual to 0.01) in the UHKS and LHKS groups when compared with the UACS and LA CS groups. Plasma electrolyte concentration, urinary electrolyte excretion, fecal potassium excretion, PRA, and PA concentration increased significant ly (p less than or equal to 0.01) in the LHKS and UHKS groups when compared with LACS and UACS groups. Urinary and fecal potassium excretion increased much more and much faster in the LHKS group than in the UHKS group. By con trast, the corresponding parameters change insignificantly in the UACS and LACS groups when compared with the base line control values, It was concluded that urinary and fecal potassium excretion increased signi ficantly despite the presence of negative potassium balance; thus, negative potassium balance may not be based on potassium shortage in the diet becau se of the impossibility of the body to retain potassium during HK.