Positioning during resistance elbow flexor exercise affects electromyographic activity, heart rate, and perceived exertion.

The main objective of this study was to compare electromyography (EMG), heart rate (HR), and perceived exertion (PE) during different elbow flexion exercises in standing position (biceps curl [BC] and adapted BC [ABC]) and seated position (preacher BC [PBC]). Twenty healthy subjects performed the dynamic 1-repetition maximum (1RM) test. The following week (1 exercise per day), these exercises were performed at 25, 30, 35, and 40% 1RM at 1 minute for each one (20 repetitions). Biceps brachii and brachioradialis root mean square (RMS), HR, and PE were recorded in the 5th (R5), 10th (R10), 15th (R15), and 20th (R20) repetitions. Effects of exercise type (BC x ABC x PBC), load level (25% 1RM x 30% 1RM x 35% 1RM x 40% 1RM), and exercise duration (R5 x R10 x R15 x R20) were analyzed. The RMS of the elbow flexors in the PBC R20 was significantly lower than BC and ABC at 40% 1RM, and, in the same way, for all load levels, HR and PE were significantly lower in PBC R20 at 40% 1RM compared with BC and ABC. For all exercises, RMS, HR, and PE at 25% 1RM were significantly lower than at 40% 1RM. The execution of the exercises caused significant increases in the RMS, HR, and PE mainly between R5 compared with R15 and R20. In conclusion, different positions demand different neuromuscular (EMG), cardiovascular (HR), and sensorial (PE) responses. A decreased effort sensation in PBC at the same relative load level can contribute to better execution when standing and seated exercises are compared.