Circadian specificity of hamstring static stretching on muscle flexibility and torque

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The current study was the first to divide subjects into morning, afternoon, and evening groups for comparison, on the basis of the assumption that there is enough variability between morning, afternoon, and evening strength and flexibility to affect the overall gains. This assumption may have been too far reaching and leading to the lack of consistent results with the current study. Thus, there was a difficulty to compare the findings of the present study with previous literature on circadian rhythm. All prior studies measured the change in each subject’s strength and flexibility over the course of a day. The present results displayed that static stretch training of trained individuals, 3 repetitions of 30 s, 5 times/week for 6 weeks, at the same time of day, produced a significant increase in the hamstring eccentric and concentric torque and flexibility. Moreover, static stretching in the afternoon and evening induced more gains in hamstring torque and flexibility than morning stretching. So, static stretching is a time-dependent task that should be considered by clinicians, coaches, and athletes to be scheduled in the afternoon or evening.

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