Plasma, urinary and fecal potassium changes in athletes during ambulatory, periodic, and continuous hypokinetic conditions

Objectives: Prolonged hypokinesia (HK) induces significant electrolyte changes, but little is known about the effect of prolonged periodic hypokinesia on plasma, urinary, and fecal K. The aim of this study was to measure potassium (K) changes during prolonged periodic (PHK) and continuous (CHK). Design and methods: Studies were done during the pre HK and HK periods. Thirty male athletes were chosen as subjects. They were divided equally into three groups: unrestricted ambulatory control subjects (UACS), continuously hypokinetic subjects (CHKS), and periodically hypokinetic subjects (PHKS). The CHKS group was kept on a running distance of 0.7 km/day, while the PHKS group kept on a running distance of 0.7 and 11.7 km/day for 5 days and 2 days per week, respectively. The UACS group was on a running distance of 11.7 km/day. Results: The following were measured: fecal K excretion; urinary K; sodium (Na) and chloride (Cl) excretion; plasma K; Na and Cl concentration; plasma renin activity (PRA) and plasma aldosterone (PA) concentration; physical characteristics; and peak oxygen uptake. Fecal K, urinary K, Na and Cl excretion, plasma K, Na and Cl concentration, and PRA and PA concentration, increased significantly (p ≤ 0.01) in the CHKS and PHKS groups when compared with the UACS group. Body weight and VO2 peak decreased significantly (p ≤ 0.01) in the CHKS group, while body weight increased and VO2 peak decreased significantly (p ≤ 0.01) in the PHKS group when compared with the UACS group. The measured parameters changed much more in the PHKS group than in the CHKS group. By contrast, the measured parameters did not change significantly in the UACS group when compared with the baseline control values. Conclusion: It was shown that prolonged PHK and CHK induce significant plasma and excretory K changes; however, plasma and excretory K changes were much greater in the PHKS group than in the CHKS group. It was concluded that the greater the stability of muscular activity, the smaller the plasma, urinary, and fecal K changes during prolonged HK.