Circadian variation of the plasma creatine kinase in healthy subjects under resting conditions day-to-day activity and after physical exercise.
Journal/Book: Chronobiologia XIV: 181 (1987). 1987;
Abstract: Institut für Arbeits-Physiologie und Rehabilitationsforschung Universität Marburg/Lahn Marburg/L. W.-Gennany. Plasma creatine kinase (CK)-levels were measured during 24h in healthy untrained subjects undergoing different physical strain: constant bed rest (n=5) bed rest interrupted by ergometric work (1.4 W/kg body weight) at 09.00 (n=5) and 13.00 (n=5) and strain imposed by ordinary day-to-day activities (n=5). Acfditionally 5 shortsrnen were measured performing ergometric work. Whereas a clear circadian rhythm of the CK was detectable under day-to-day activities CK-values coutinuously decreased under constant resting conditions and however the deviation from this trend showed a slight circadian rhythm. Ergometric acivity caused a transitory increase of the CK passing over into a decrease corresponding to the resting conditions. The individual extent of the increase was significantly correlated with the physical working capacity of the respective subject. It is concluded that the circadian rhythm of the plasma-CK depends on physical strain during day time and therefore it is not detectable under resting conditions.