Effects of stretching on peak torque and the H:Q ratio

The purpose of the present study was to examine the acute effects of hamstring and calf stretching on leg extension and flexion peak torque (PT) and the hamstrings-to-quadriceps (H:Q) ratio during maximal, concentric isokinetic muscle actions at 60, 180, and 300° • s^-1 in women. Thirteen women (mean age ± SD = 20.8 ± 1.8 yrs; height = 163.0 ± 5.7 cm; mass = 64.0 ± 8.3 kg) performed 3 maximal concentric isokinetic leg extension and flexion muscle actions at 3 randomly ordered angular velocities (60, 180, and 3008 • s^-1) before and after a bout of static stretching. The stretching protocol consisted of 1 unassisted and 3 assisted static stretching exercises designed to stretch the posterior muscles of the thigh and leg. Four repetitions of each stretch were held for 30 s with 20 s rest between repetitions. The results indicated that leg flexion PT decreased from pre- to poststretching (34.9 ± 3.5 and 32.4 ± 3.2 Nm, respectively) collapsed across velocity. However, no other changes were observed from pre- to poststretching for leg extension PT (78.5 ± 5.9 and 77.8 ± 5.5 Nm, respectively) and the H:Q ratio (0.47 ± 0.04 and 0.44 ± 0.03, respectively). Our findings suggested that despite the stretching-induced decreases in leg flexion PT, leg extension PT and the H:Q ratios were unaltered by the stretching.