Abstract
This study examined the acute effects of dynamic stretching at different velocities on the neuromuscular system. Fourteen participants underwent four experimental sessions in random order: (1) control (lying at rest with the ankle in a neutral position); (2) slow velocity dynamic stretching (50 beats/min; SLOW(DS)); (3) moderate velocity dynamic stretching (70 beats/min; MOD(DS)); and (4) fast velocity dynamic stretching (90 beats/min; FAST(DS)). The stretching protocols consisted of four sets of 10 repetitions and targeted the plantar flexor muscles of the right ankle. Assessments included corticospinal excitability (via motor-evoked potential-MEP/M(max)), spinal reflex activity (via H-reflex-H(max)/M(max)), muscle contractile properties (peak twitch torque; PTT), maximal voluntary contraction (MVC), and maximal range of motion (ROM(max)). Dynamic stretching did not affect MEP/M(max) and MVC of the plantar flexor muscles (P > 0.05). All stretching protocols similarly reduced soleus H(max)/M(max) (P < 0.05), and increased PTT (P < 0.05). Additionally, all conditions, including control, similarly increase ROM(max) (P < 0.05, and Cohen's d value of -0.39, -0.28, -0.38 and -0.29 for CON, SLOW(DS), MOD(DS) and FAST(DS), respectively). Therefore, dynamic stretching reduces spinal reflex activity and enhances muscle contractile properties irrespective of movement velocity without impairing corticospinal excitability and MVC.