Unique neuromuscular activation of the rectus femoris during concentric and eccentric cycling.

This study investigated neuromuscular activations of thigh muscles during concentric cycling (CONcycling) and eccentric cycling (ECCcycling). Eleven untrained men completed 30 s of CONcycling and ECCcycling each at 5 power outputs of 100-300 W (every 50-W interval). During cycling, root mean square of surface electromyographic signals (RMS-EMG) were obtained from the proximal and distal regions of the rectus femoris (RFp and RFd), vastus lateralis (VL), and biceps femoris (BF). The rating of perceived exertion (RPE) was evaluated using the 6-20 Borg Scale. The RMS-EMG of VL and BF were 21.6%-67.6% higher (P < 0.05) during CONcycling than ECCcycling at all power outputs, while those of RFp and RFd at 100-200 W were 29.6%-40.4% lower during CONcycling than ECCcycling. The RPE was similar between CONcycling at 150 W (10 ± 2) and ECC at 250 W (10 ± 2). There were no significant differences in the RMS-EMG for VL or BF between CONcycling at 150 W and ECCcycling at 250 W; however, the RF RMS-EMG was greater during ECCcycling as compared with CONcycling. There were no regional differences in RF activations. These results demonstrated the unique neuromuscular activation of RF as compared to those of other thigh muscles during CONcycling and ECCcycling.