An Electromyographic Analysis of Lateral Raise Variations and Frontal Raise in Competitive Bodybuilders

The present study examined the muscle activation in lateral raise with humerus rotatedexternally (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 bodybuildersperformed the exercises. Normalized surface electromyographic root mean square (sEMG RMS)was obtained fromanterior,medial, andposterior deltoid,pectoralis major,upper trapezius, andtricepsbrachii. During the concentric phase,anterior deltoidandposterior deltoidshowed greater sEMG RMS infrontal raise (effect size (ES)-range: 1.78/9.25)) and LR-internal (ES-range: 10.79/21.34), respectively,vs. all other exercises.Medial deltoidshowed 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)).Pectoralis majorshowed greater sEMG RMS in frontalraise vs. all other exercises (ES-range: 17.2/29.5), whileupper trapezius(ES-range: 2.66/7.18) andtriceps brachii(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 ofposterior deltoid,triceps brachii, andupper trapeziusoccurs. Humerus externalrotation increases the activation ofanteriorandmedial deltoid.Frontal raise mainly activatesanteriordeltoidandpectoralis major. LR variations and frontal raise activate specifically shoulders muscles andshould be proposed accordingly.