Circadian variation of isometric muscle strength training in man

Journal/Book: In: E. MORGAN (Ed.): Chronobiology and Chronomedicine. Vol. II. P. Lang Frankfurt - Bern - New York - Paris 1990 p. 322-329. 1990;

Abstract: Institut für Arbeitsphysiologie und Rehabilitationsforschung der Philipps-Universität Marburg Robert-Koch-Strasse 7a D-3550 Marburg/Lahn FRG Introduction Ample information is available on circadian variations on immediate reactions to various stimuli. However when repeated stimuli are applied over a longer period the extent to which adaptive long-term responses of the organism depend on the time of day or the phase of the circadian system respectively is not clear. Up to now there is some information on habituation to cold stimuli (Hildebrandt & Strempel 1977) as well as on endurance training (Baier & Rompel 1977). This study was performed in order to verify whether the result of isometric muscle strength training depends on the phase of the circadian rhythm. Methods In the first part of the study four groups of healthy female subjects (n=6-7) performed a seven-day isometric strength training programme. This involved three different muscle groups (knee extensors elbor flexors and elbow extensors) and consisted of ten maximal voluntary contractions each of six seconds duration with one minute intervals. Each group trained at a different time of day (03.00 09.00 15.00 21.00 h). After a visual warning the subjects had to perform a maximal voluntary contraction according to the duration of an acoustical signal. Measurements of maximal strength were performed using a dynamometer according to Hettinger ( 1968). . . . .

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