Potential Relevance of Altered Muscle Activity and Fatigue in the Development of Performance-Related Musculoskeletal Injuries in High String Musicians.

BACKGROUND: Muscle fatigue seems to be a risk factor in the development of performance-related musculoskeletal disorders (PRMDs) in musicians, but it is unclear how muscle activity characteristics change between musicians with and without PRMDs over a prolonged playing period.

PURPOSE: To investigate muscle activity patterns in muscles of the arms, shoulder, and back of high string musicians during prolonged performance.

METHODS: Fifteen professional or university high string musicians were divided into PRMD and non-PRMD groups. All musicians played a chromatic scale, then an individual "heavy" piece for 1 hr, and finally the chromatic scale again. Surface electromyography (sEMG) data were recorded from 16 muscles of the arm, shoulder, and trunk on both sides of the body. Two parameters were analyzed: the percentage load in relation to the respective maximum force during the chromatic scale, and the low-frequency spectrum to determine the fatigue behavior of muscles during the 1-hr play.

RESULTS: Changes in muscle activation patterns were observed at the beginning and end of the trial duration; however, these varied depending on whether musicians had PRMDs or no PRMDs. In addition, low-frequency spectrum changes were observed after 1 hr of playing in the PRMD musicians, consistent with signs of muscular fatigue.

CONCLUSION: Differences in muscle activity appear between high string musicians with and without PRMDs as well as altered frequency spectrum shifts, suggesting possible differential muscle fatigue effects between the groups. The applied sEMG analysis proved a suitable tool for detailed analysis of muscle activation characteristics over prolonged playing periods for musicians with and without PRMDs.