Comparison of Muscle Activation between Open and Closed Chain Hinge Exercises

Hinge pattern resistance training exercises prioritize hip flexion and extension, and are often paired with squat pattern exercises to develop the lower body musculature comprehensively. However, few studies have examined biomechanical differences between various exercises that fit within the hinge movement pattern to optimize their selection towards specific goals and considerations. Differences in the kinetic chain of an exercise may alter muscle activation, and therefore exercise-specific applicability. For example, a Romanian deadlift (RDL) is a closed-chain exercise, while a reverse hyperextension (RH) is open-chain. To develop our understanding further, the muscle activation of the RDL and RH was compared in apparently healthy males. To determine load for the study, participants completed repetition-maximum (RM) testing on the RDL and RH. On a follow-up visit, surface electromyography (EMG) of the longissimus, multifidus, gluteus maximus, semitendinosus, and biceps femoris (lumbar/hip extensors) was measured using standard procedures. After a standardized warm-up protocol, participants completed maximal voluntary isometric contractions (MVICs) in the five muscles mentioned above. Participants then completed five slow (2s concentric, 2s eccentric) repetitions of the RDL and RH at 50% of estimated 1RM. The testing order was randomized. A repeated-measures ANOVA was then used to compare muscle activation (%MVIC) between the RDL and RH. Changing from a closed- (RDL) to an open-chain (RH) increased muscle activation in the gluteus maximus (+19.5%), biceps femoris (+27.9%), and semitendinosus (+18.2%). Interestingly, the differences in gluteus maximus, biceps femoris, and semitendinosus activation in these exercises were found specifically in the eccentric phase of contraction. Simple alterations in the execution of hinge movement may therefore alter the activation of muscles that impact lumbar/hip extension.