EMG Changes In Fatigue

Abstract

INTRODUCTION: Instrumental musicians frequently undergo similar levels of physical strain to sport athletes, yet the physical demands of musicianship are rarely considered during practices/rehearsals. PURPOSE: To develop a quantitative model of fatigue in violin performance and provide a basis for smarter practice/rehearsal programming. METHODS: This study was conducted in three distinct phases: (1) MEDLINE, PubMed, Web of Science, SportDISCUS, and Cochrane Library were searched for articles reporting changes in electromyographic (EMG) amplitude and/or frequency data during constant force isometric, intermittent isometric, or dynamic contraction protocols ≥20 seconds. Meta-analysis was conducted using general regression models to model the relations between initial EMG levels and both the rate of change in EMG and time to failure. (2) Professional/university violinists (n=55; ≥10 years experience) performed 5 randomly ordered 45-second music excerpts designed to elicit 5 typical right arm movements. Surface EMG data were obtained for 16 relevant muscles of the core, shoulders, chest, and right arm during excerpt performances. (3) Models from the meta-analysis were applied to the EMG data during violin performance. RESULTS: Database searches identified 7273 articles; after removal of duplicates, 5079 articles were screened and 82 articles were included in the meta-analysis. Meta-analysis revealed that a higher initial EMG contraction intensity was associated with a greater rate of change of EMG amplitude (%MVC/min) and a shorter time to task failure (min). During violin performance, average EMG amplitude ≤12.5% MVC for investigated core, shoulder, and upper arm muscles across all excerpt performances; wrist flexors and extensors ranged from 11.8% MVC (excerpt #5) to 55.8% MVC (excerpt #4). Applying the results of the meta-analysis, the rate of EMG amplitude increase and time to task failure were estimated to range from 0 - 38.9 %MVC/min and .88 - 42.4 min, respectively, during violin performance. CONCLUSION: The physical demands of instrumental music performance vary widely with repertoire and must be considered during practice/rehearsal programming to minimize fatigue and injury risk. **Research supported by the Australian-American Fulbright Commission and Australian Research Council**