Does Static Stretching Compromise Jump Performance in Diurnal Variation? The Effect of Static Stretching in Diurnal Variation

The purpose of the study was to investigate the effect of static stretching on squat jump (SJ) and countermovement jump (CMJ) in diurnal variation. Fifty-three male collegiate athletes (age=21.9±2.6 years; height=179.7±8.1cm; body-mass=75.3±8.6kg; mean±SD) completed the SJ and CMJ tests either after static stretching or no stretching protocols at two times of the day (07:00h and 17:00h) in random order on non-consecutive days. After warming-up for 5 minutes with low-intensity jogging, participants walked for 2 minutes before performing one of the two stretching protocols (static stretching or no stretching) then 4-5 minutes of additional rest was given before SJ and CMJ performances were measured. Jump heights were analyzed using the two-way ANOVA with repeated measures (2[stretching]×2[time-of-day]). No stretching protocol caused better jump heights in both SJ and CMJ (p< .01). SJ heights were higher at 17:00 compared to 07:00 in both static stretching (8.8%) and no stretching (9.1%) protocols (p< .01). Similarly, CMJ heights were higher at 17:00 compared to 07:00 in both static stretching (10.6%) and no stretching (5.8%) protocols (p< .01). Static stretching adversely influenced jump heights both in the morning and evening. However, it caused less negative effect in the evening.