The acute effects of static stretching on peak torque, mean power output, mechanomyography, and electromyography during maximal, eccentric isokinetic muscle actions

The purposes of this study were to examine the acute effects of static stretching on peak torque (PT), mean power output (MP), mechanomyographic (MMG) amplitude, MMG mean power frequency (MPF), electromyographic (EMG) amplitude, and EMG MPF of the vastus lateralis (VL) and rectus femoris (RF) muscles during maximal, eccentric isokinetic muscle actions at 60 and 180°·s −1 of the stretched and unstretched limbs in males and females. Thirteen females (mean ± SD age = 21 ± 1 years) and fifteen males (23 ± 2 years) volunteered to participate in the investigation. PT of the right (stretched) and left (unstretched) leg extensors were measured on a calibrated Cybex 6000 dynamometer at randomly ordered velocities of 60 and 180°·s−1. MP was determined by the dynamometer software. Following the pre-stretching isokinetic assessments, the right leg extensors were stretched using one active and three passive stretching exercises. After the stretching, PT and MP were reassessed. MMG and EMG signals were recorded from the VL and RF muscles during each isokinetic assessment. The results indicated no changes (p \u3e 0.05) in PT from pre- to post-stretching. There were, however, stretching-induced decreases (p \u3c 0.05) in MP that were accompanied by decreases (p \u3c 0.05) in MMG amplitude in the RF muscle. No meaningful changes were evident from pre- to post-stretching for MMG MPF, EMG amplitude, or EMG MPF. These results supported the hypothesis of Bodor (9), which suggested that MMG amplitude is more closely related to MP than PT during maximal isokinetic muscle actions. Furthermore, in conjunction with previous studies, these results suggested that the isokinetic responses to static stretching for PT are mode-specific