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Context: Scapular retraction exercises are often prescribed to enhance scapular stabilization. Objectives: To investigate the upper trapezius (UT), middle trapezius (MT), lower trapezius (LT) activities, and UT/MT and UT/LT ratios during scapular retraction exercise with elastic resistance at different shoulder abduction angles. Design: Descriptive laboratory study. Setting: Biomechanical analysis laboratory. Patients or Other Participants: Thirty-five asymptomatic individuals. Main Outcome Measures: Surface electromyography was used to evaluate UT, MT, and LT activities during the scapular retraction exercise at 0º, 45º, 90º, and 120º shoulder abductions. Results: The mean muscle activity ranged from 15.8%–54.7% maximum voluntary isometric contraction (MVIC) for UT, 30.5%–51.6% MVIC for MT, 21.4%–25.5% MVIC for LT. A significant "muscle×angle" interaction was found (p<0.001). Post hoc analysis revealed that the MT was significantly more activated than UT and LT during both retraction at 0º (p<0.001; p=0.01, respectively) and 120º (p=0.03; p=0.002, respectively). During retraction at 45º and 90º, the LT generated significantly lower activity than the UT (p=0.02; p=0.03, respectively) and MT (p<0.001; p=0.002, respectively). Besides, UT/MT and UT/LT ratios during retraction at 0º were significantly lower than 45º (p=0.03; p=0.001, respectively) and 90º (p<0.001; p<0.001, respectively). Retraction at 90º resulted significantly higher UT/LT ratio than 45º (p=0.004) and 120º (p=0.004). Conclusions: Due to lower UT activity relative to MT, retraction at 0º, 45º, and 120º can be preferred in early shoulder training or rehabilitation. Additionally, retraction at 90º was the most effective exercise in activating entire trapezius muscle parts.

Context: The wall slide exercise is commonly used in clinic and research settings. Theraband positioning variations for hip exercises are investigated and used, but theraband positioning variations for upper extremity wall slide exercise, though not commonly used, are not investigated. Objective: To investigate the effect of different theraband positions (elbow and wrist) on scapular and shoulder muscles' activation in wall slide exercises and compare them to the regular wall slide exercise for the upper limbs. Study Design: Descriptive Laboratory Study. Setting: University Laboratory Patients or Other Participants: 20 participants with healthy shoulders Interventions: Participants performed regular and two different variations of wall slide exercises (theraband at wrist and theraband at elbow) in randomized order. Main Outcome Measures: Surface EMG activity of the trapezius muscles (upper [UT], middle [MT], and lower trapezius [LT]), infraspinatus (IS), middle deltoid (MD), and serratus anterior (SA). Results: Regular wall slide exercise elicited low activity in MD and moderate activity in SA muscles (32% MVIC), while theraband at wrist and elbow variations elicited low activity in MT, LT, IS, and MD muscles and moderate activity in SA muscles (46% and 34% MVICs, respectively). UT activation was absent to minimal (0–15% MVIC) in all wall slide exercise variations. Theraband at wrist produced lower UT/MT, UT/LT, and UT/SA levels. Conclusion: In shoulder rehabilitation, clinicians desiring to activate scapular stabilization muscles should consider using theraband at wrist variation; clinicians desiring to achieve more shoulder abduction activation and less scapular stabilization should consider theraband at elbow variation of upper extremity wall slide exercise.

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