ABSTRACT
OBJECTIVES: The purpose of the study was to evaluate performance quality of shoulder plyometric exercises, and examine the relationship to scapular muscle activation during an intense exercise bout. DESIGN: Observational study. SETTING: University laboratory. PARTICIPANTS: 32 healthy university students (male/female: 14/18) volunteers. MAIN OUTCOME MEASURES: Subjects performed 10 plyometric exercises. Surface EMG of upper (UT), middle (MT) and lower (LT) trapezius and serratus anterior (SA) was registered. A quality assessment questionnaire was administered at the beginning and end of the exercise bout. Muscle activation at the beginning and end was evaluated by t-test. Mixed repeated measures ANOVA was conducted to test the effects of criterion-quality, time, muscles, exercises, and their interactions. RESULTS: Increased EMG activation was noted in 34/40 cases, (21/40 significant (p < 0.05) changes). Quality assessment revealed a decline in the ability to maintain initial position (43% of subjects), failure to keep a consistent and symmetrical arc of motion (62% of subjects), and performance with trick movements (48% of subjects). Inability to keep a consistent arc of motion was significant in 4 exercises. CONCLUSIONS: The novel questionnaire may aid quality assessment during plyometric exercises. Ability to keep a consistent arc of motion was the most sensitive marker of decline of performance quality.
