High-density surface electromyography excitation in front vs. back overhead press prime movers

The current study compared the spatial excitation of the prime movers when performing the overhead press with the barbell passing in front (front-OHP) or behind the neck (back-OHP) using high-density surface electromyography (HD-sEMG). Fourteen resistance trained men performed both exercises within a non-fatiguing set with 8-RM as the external load. The HD-sEMG amplitude and the muscle excitation centroid of anterior deltoid, lateral deltoid, posterior deltoid, upper trapezius, pectoralis major and triceps brachii muscles were recorded during the ascending and the descending phase. During the ascending phase, the front-OHP showed a superior HD-sEMG amplitude of the anterior deltoid (ES = 1.03) and the pectoralis major (ES = 0.70). During the descending phase, the front-OHP showed a superior HD-sEMG amplitude of the anterior deltoid (ES = 1.00) and the pectoral major (ES = 0.74), while the back-OHP showed superior excitation of the posterior deltoid (ES = 1.11), the upper trapezius (ES = 0.72) and triceps brachii (ES = 2.01). During the ascending phase, the front-OHP showed a more medial centroid of the lateral deltoid (ES = 2.30). During the descending phase, the front-OHP showed a more lateral centroid of the lateral deltoid (ES = 0.87), whereas the centroid of the posterior deltoid (ES = 0.63) and the triceps brachii (ES = 0.68) was more medial. Additionally, the centroid was more cranial in the front- vs. the back-OHP for the posterior deltoid (ES = 1.10), while for the pectoralis major the centroid was more caudal (ES = 0.62). The front- and back-OHP appeared to provide different overall excitation in the prime movers. Moreover, distinct spatial excitation patterns were observed, making both exercises suitable for the training routine.