title: Shoulder Muscle Activation Levels During Exercises With Axial and Rotational Load on Stable and Unstable Surfaces.
abstract: This study evaluated the effects of instability on the EMG activity of scapular stabilizing and upper limb muscles during exercises with axial and rotational load. Twenty male volunteers (20.9 ± 1.8 years, 174.1 ± 0.04 cm, 73.17 ± 8.77 kg) experienced in strength training participated in a crossover design. Muscle activation of anterior deltoid (AD), posterior deltoid (PD), pectoralis major (PM), biceps brachii (BB), triceps brachii (TB), upper trapezius (UT), middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) were determined on both conditions. Participants performed a single series of 10 repetitions of bench press and fly exercises on stable (bench) and unstable (proprioceptive disc) conditions at 60% of 1-RM. The Friedman test and post hoc Dunn's indicated that the unstable condition showed greater EMG activity for AD (P = .001) and BB (P = .002) on the fly exercise, SA (P = .001) and LT (P = .048) on the bench press, and PM (P ≤ .002) on both exercises. These results show that using an unstable surface in exercises with rotational load provides superior EMG activity of the agonist muscles, while in exercise with axial load, the instability favors EMG activity of the scapular stabilizing muscles.
authors.affiliation: 1 University of Pernambuco.
authors.forename: Vinícius Yan Santos
authors.initials: VY
authors.lastname: Nascimento
authors.affiliation: 1 University of Pernambuco.
authors.forename: Rafaela Joyce Barbosa
authors.initials: RJ
authors.lastname: Torres
authors.affiliation: 1 University of Pernambuco.|2 Federal Rural University of Pernambuco.
authors.forename: Natália Barros
authors.initials: NB
authors.lastname: Beltrão
authors.affiliation: 1 University of Pernambuco.
authors.forename: Priscila Soares Dos
authors.initials: PS
authors.lastname: Santos
authors.affiliation: 1 University of Pernambuco.|3 Asces College.
authors.forename: André Luiz Torres
authors.initials: AL
authors.lastname: Pirauá
authors.affiliation: 1 University of Pernambuco.
authors.forename: Valéria Mayaly Alves de
authors.initials: VM
authors.lastname: Oliveira
authors.affiliation: 1 University of Pernambuco.
authors.forename: Ana Carolina Rodarti
authors.initials: AC
authors.lastname: Pitangui
authors.affiliation: 1 University of Pernambuco.
authors.forename: Rodrigo Cappato de
authors.initials: RC
authors.lastname: Araújo
mesh_terms: D001132:Arm / Q000502:physiology*; D004576:Electromyography; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D012399:Rotation; D012785:Shoulder Joint / Q000502:physiology*; D013647:Task Performance and Analysis; D014891:Weight Lifting / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult
keywords: electromyography; scapula; upper limb