Effects Of Warm-up On Peak Torque, Rate Of Torque Development, And Electromyographic And Mechanomyographic Signals

Abstract

PURPOSE: The purpose of this study was to determine if an active warm-up affects peak torque (PT), rate of torque development (RTD), and the electromyographic (EMG) and mechanomyographic (MMG) signals. METHODS: Twenty-one men (mean age ± SD = 23.9 ± 2.6 y) visited the exercise physiology lab on two occasions. During the first visit they either performed an active warm-up (10 minutes of stationary cycling at 70% of predicted max heart rate) or sat quietly (no warm-up). Participants were then tested for isometric and isokinetic PT (60, 180, and 300 deg/s), and RTD (measured as S-gradient) on an isokinetic dynamometer. EMG and MMG sensors were placed over the vastus lateralis muscle of the right limb to monitor the electrical and mechanical aspects of muscle contractions, respectively. The testing protocol used for the first visit was repeated for the second visit, but the pre-exercise treatment (warm-up, no warm-up) not given during the first visit was administered. RESULTS: The results indicated that an active warm-up did not affect PT, RTD, EMG amplitude, EMG frequency, or MMG frequency (p > 0.05). However, MMG amplitude at 180 deg/s was significantly greater (p < 0.05) in the warm-up condition compared to the no warm-up condition. CONCLUSIONS: The results indicated that warm-up did not affect PT, RTD, EMG amplitude, EMG frequency, or MMG frequency. The increase in MMG amplitude, however, suggests that warm-up may have affected the mechanical properties of muscle by reducing muscular stiffness and/or decreasing intramuscular fluid pressure.