The purpose was to examine if there were changes in muscular performance if the activity was preceded by an active warm up. Twenty-one men (mean age ± SD = 23.9 ± 2.6 y) participated in two trials (active warm-up and control) and performed isometric and isokinetic knee extensions. EMG and MMG sensors were placed over the vastus lateralis muscle to detect neurological signals. Torque and rate of torque development were recorded by an isokinetic dynamometer. PT, EMG and MMG amplitude, and EMG and MMG MPF data were analyzed using two-way (velocity × condition) repeated measures ANOVAs. RTD data were analyzed using a paired t-test. The results indicated no significant two-way interaction for PT. However, the PT data did demonstrate a significant main effect for velocity (60 > 180 > 300°s-1). There were no significant (p > 0.05) two-way interactions or main effects for EMG amplitude, EMG frequency, or MMG frequency. There was, however, a significant two-way interaction for MMG amplitude. MMG amplitude at 180°·s ^-1was significantly greater in the warm-up condition compared to the no warm-up condition. There was no significant difference (p > 0.05) in RTD between the warm-up and no warm-up conditions.

Changes in MMG amplitude occurred, but not MPF, at 180°s^-1 , during the warm-up trial. There were no significant differences in PT, RTD or EMG between trials. The results suggested that mechanical changes, decreases in muscular stiffness or decreased intramuscular fluid viscosity, occurred as a result of performing an active warm-up.