Reduced muscle activity during isokinetic contractions associated with external leg compression.

BACKGROUND The potential mechanism of compression apparel remains unclear to date because of insufficient knowledge on the influence of compressive level on muscular responses. OBJECTIVE To explore the influence of external leg compression on (a) the muscle force and endurance of the quadriceps femoris and (b) the muscle activation patterns during prolonged muscle actions. METHODS Twelve male participants performed consecutive maximal concentric muscle actions of the quadriceps in compression garment (CG) and control condition (CON) at two angular velocities on the Contrex. The EMG amplitude and frequency of the rectus femoris (RF), vastus lateralis (VL), and vastus medialis were quantified during the concentric phase of the knee extension movement. RESULTS There was no significant compression effect on muscle force and total work during knee extensions. Contrarily, the overall EMG amplitude was significantly lower in CG than in CON at 60 and 300°/s. Additionally, the EMG frequency of the RF and VL was significantly higher in CG than in CON at 60°/s. CONCLUSION Increased external pressure is associated with changes in EMG time and frequency domain behavior. These effects can potentially relieve muscle fatigue and improve muscle endurance during long-term exercise.