Giuseppe Coratella, Gianpaolo Tornatore, Stefano Longo, Fabio Esposito, Emiliano Cè
The present study examined the muscle activation in lateral raise with humerus rotated externally (LR-external), neutrally (LR-neutral), internally (LR-internal), with flexed elbow (LR-flexed) and frontal raise during both the concentric and eccentric phase. Ten competitive bodybuilders performed the exercises. Normalized surface electromyographic root mean square (sEMG RMS) was obtained from , , and , , , and . During the concentric phase, and showed greater sEMG RMS in frontal raise (effect size (ES)-range: 1.78/9.25)) and LR-internal (ES-range: 10.79/21.34), respectively, vs. all other exercises. showed greater sEMG RMS in LR-neutral than LR-external (ES: 1.47 (95% confidence-interval-CI: 0.43/2.38)), frontal raise (ES: 10.28(95% CI: 6.67/13.01)), and LR-flexed (ES: 6.41(95% CI: 4.04/8.23)). showed greater sEMG RMS in frontal raise vs. all other exercises (ES-range: 17.2/29.5), while (ES-range: 2.66/7.18) and (ES-range: 0.41/3.31) showed greater sEMG RMS in LR-internal vs. all other exercises. Similar recruitment patterns were found during the eccentric phase. When humerus rotates internally, greater activation of , , and occurs. Humerus external rotation increases the activation of and Frontal raise mainly activates and . LR variations and frontal raise activate specifically shoulders muscles and should be proposed accordingly.
