Circadian variation in human flexibility and grip strength.

The main aim of this study was to monitor changes in joint flexibility over 24 hours in 25 subjects. Measurements of finger tip to floor, lumbar flexion, lumbar extension, passive straight leg raising and glenohumeral lateral rotation at 90° abduction were taken every two hours during the 24 hour cycle. The presence of circadian rhythms in flexibility were established by graphical analysis of the results. These were shown to exist in all measurements, the most strong being finger tip to floor and most weak glenohumeral lateral rotation. The study also investigated grip strength over 24 hours and disclosed a circadian pattern in which there was a considerable fall in strength during the early hours and a rapid rise after 0600 hours.