Electromyographic changes in prime movers during fatiguing dynamic and isometric bench presses

This is the authors' abstract. We don't add key points for this paper.

BACKGROUND: The amplitude and median power frequency (MPF) of surface electromyographic (EMG) signals are considered well-suited for monitoring the progression of fatigue. The aim of this study was to examine changes in the amplitude and MPF of surface EMG signals from prime movers during fatiguing dynamic and isometric bench presses.METHODS: In Experiment-1, the EMG amplitudes of the upper, middle, and lower parts of the pectoralis major muscle (PMU, PMM, and PML, respectively), anterior deltoid (AD), and the triceps brachii (TB) were measured during fatiguing dynamic bench press at 70% of one-repetition maximum (1RM) in 19 men. In Experiment-2, the EMG amplitude and MPF of the aforementioned muscles were measured during fatiguing isometric bench press at 70% of 1RM in 16 men.RESULTS: EMG amplitudes of PMU, PML, and AD significantly increased from the first to the final repetition of the dynamic bench press. However, EMG amplitudes of PMM and TB significantly increased only up to 75% and 50% of repetitions, respectively. EMG amplitude was significantly higher in PMM and PML compared to PMU at the beginning of isometric bench press, and higher in PML compared to TB at exhaustion. Additionally, MPF decreased significantly across all muscles from 25% to 100% of the time to exhaustion.CONCLUSIONS: Among the prime movers in bench press, the pectoralis major muscle appears to be preferentially recruited and subsequently fatigued.