The long-term effects of static stretching at different times of day on hamstring peak torque and flexibility in trained individuals

Abstract

Introduction. There is some recent evidence that temporal specificity is important for optimizing training for muscular performance. This study was to examine the long-term effects of static stretching performed at different times of day on hamstring torque and flexibility. Methods. The total of 60 trained male subjects with tight hamstring were selected and randomly divided into 3 equal groups. Group A received static stretch in the morning (07:00-9:00), group B in the afternoon (13:00-16:00), and group C in the evening (18:00-20:00). The hamstring isokinetic concentric and eccentric peak torque and knee extension range of motion were assessed before and after 6 weeks of static stretching (3 repetitions of 30 s, 5 times/week). Results. A statistically significant increase was observed in hamstring concentric and eccentric torque, and flexibility after static stretching at different times of day (p < 0.05). The concentric and eccentric torque post-training values were significantly higher than the pre-training values (p < 0.05). The hamstring flexibility post-training values of groups B and C were significantly higher than for group A (p < 0.05). The torque and flexibility change scores of groups B and C were significantly higher than for group A (p < 0.05), without any significant difference between groups B and C (p > 0.05).Conclusions. Afternoon and evening static stretching is more effective than morning stretching in improving the hamstring concentric and eccentric torque and flexibility. Therefore, static stretching is a time-dependent task and should be scheduled by clinicians, coaches, and athletes in the afternoon or evening.