Electromyographical Assessment of Passive, Active Assistive, and Active Shoulder Rehabilitation Exercises

Objective: To determine the electromyographical (EMG) activation levels of shoulder musculature during early rehabilitation exercises to regain active range of motion. Design: Descriptive. Setting: University clinical research laboratory. Participants: Ten asymptomatic volunteers (age, 25 ± 5 years; height, 171 ± 7 cm; weight, 78 ± 15 kg). Intervention: Fine-wire (supraspinatus and infraspinatus) and surface (anterior deltoid, upper trapezius, lower trapezius, and serratus anterior) electrodes recorded EMG activity from each muscle during 12 therapeutic exercises completed during a single testing session in random order. Main Outcome Measure: EMG root mean squared amplitude normalized to a percentage of maximum voluntary contraction (% MVC). Results: Passive exercises generated the lowest mean EMG activity (<10%) for all muscles studied. The standing active shoulder elevation exercises generated the greatest mean EMG activity with an upper boundary of 95% CI (40% MVC). Overall the active-assistive exercises generated a small (<10%) increase in muscle activity compared with the passive exercises for the supraspinatus and infraspinatus muscles, which was not a significant increase (P > .05). Conclusion: This electrophysiological data in normal volunteers suggest that many exercises used during the early phase of rehabilitation to regain active elevation do not exceed 20% MVC. Progression from passive to active-assisted can potentially be performed without significantly increasing muscular activation levels exercises. Upright active exercises demonstrated a consistent and often a statistically significant increase in muscular activities supporting that these exercises should be prescribed later in a rehabilitation program.