EMG analysis of concurrent activation potentiation.

Purpose: This study evaluated the effect of remote voluntary contractions(RVC) on concentric isokinetic knee extensor and flexor peak torque, rate of torque development, power, and work, the activation of the affected muscles, and gender differences therein.

Methods: Eleven men and 12 women were evaluated with EMG and isokinetic dynamometry during knee extension and flexion tests in RVC and baseline (NO-RVC) test conditions. The RVC condition included jaw clenching, hand gripping, and the Valsalva maneuver. A two-way mixed ANOVA with repeated measures for test condition was used to evaluate the main effects for each isokinetic measure, as well as the EMG of the prime movers, their antagonist,and the muscles involved in the RVC, and the interaction between test condition and gender.

Results: Significant interactions between test condition and gender indicate differences in response to RVC during knee extension tests for power and work (P < or = 0.05) and for knee flexion tests for peak torque and power (P < or = 0.05). All subjects produced higher peak torque and power during knee extension in the RVC condition (P < or = 0.05). Men produced a higher rate of torque development and work during knee extension (P < or = 0.05) and a higher peak torque and power during knee flexion in the RVC condition (P < or = 0.05). Prime mover activation was greater in the RVC condition for most tests (P < or = 0.05). Women demonstrated lower bilateral flexor digitorum superficialis activation than men during all tests in the RVC condition (P < or = 0.05).

Conclusions: RVC increased the performance of several outcome variables assessed, which coincides with the concomitant increase in EMG of the prime movers.