INTRODUCTION AND LITERATURE REVIEW Prevalence of Playing-related Musculoskeletal Disorders Musculoskeletal problems among professional musicians

Work-related musculoskeletal disorders in the neck– shoulder area are common among violin and viola players. The aim of this study was to investigate the influence of playing-related musculoskeletal disorders (PRMDs) on muscle activity, by measuring electromyographic activity in the upper trapezius (UT) muscles of violin and viola players under three experimental conditions: rest, performance of an easy piece, and performance of a difficult piece. Ten professional violin and viola players from a Scottish orchestra volunteered to take part in the study. Five subjects complained of pain in the neck–shoulder region; five were pain-free. Bilateral surface electromyography (EMG) was used, following submaximal reference voluntary contractions, to record the muscle activity of the UT muscles during the three experimental conditions. Subjects were randomly allocated to the conditions. A four-factor balanced analysis of variance (ANOVA) was performed. The results revealed that the pain-free subjects developed more UT muscle activity than subjects experiencing neck–shoulder pain (F = 4.07, df = 1, p = 0.05). Furthermore, the subjects developed significantly more UT activity when progressing from the rest condition to performance of the difficult piece (F = 36.64, df = 2, p < 0.001). The PRMD subjects developed more UT activity than the pain-free subjects at rest. The opposite tendency was observed for the playing conditions. However, the results were not statistically significant for this interaction (F = 1.85, df = 2, p = 0.169). The results suggest that redistribution of the load to other synergistic muscles may be a strategy used by PRMD subjects to alleviate pain or discomfort at the neck–shoulder area. The voluntary monitoring of shoulder muscle activity may be of great importance in the prevention of PRMDs in viola and violin players. Med Probl Perform Art 17:68–75, 2002. INTRODUCTION AND LITERATURE REVIEW Prevalence of Playing-related Musculoskeletal Disorders Musculoskeletal problems among professional musicians are in most ways no different from musculoskeletal problems associated with any other occupation; most types of work require that certain bodily movements and positions be used in a repetitive manner.1,2 Throughout the 1980s and 1990s, numerous epidemiological studies were undertaken in an attempt to identify the incidence, prevalence, nature and severity of playing-related musculoskeletal disorders (PRMDs) experienced by musicians.3-8 Following her systematic review, which highlighted the heterogeneity of these studies, Zaza2 found that the prevalence of PRMDs in musicians ranged from 39% to 47%, when mild and transient complaints were excluded, with PRMDs defined as “pain, weakness, numbness, tingling, or other symptoms that interfere with (their) ability to play (their) instrument at the level (they) are accustomed to.” 9 The largest published study ever undertaken involving professional orchestra musicians surveyed a population of 4,025 musicians from 48 orchestras (the International Conference of Symphony and Opera Musicians: ICSOM) in the United States in 1986.5 With a response rate of 55%,2 this study reported that 76% of musicians had at least one medical problem severe enough to affect their performance. String players, whose playing requires both repetitive actions10 and static loading,11 had the highest risk of PRMDs (66% prevalence), with the neck and shoulder being the prime sites affected.5,6 By combining location of PRMD, instrument, and gender, the researchers found that female violin players had a significantly higher percentage (p < 0.05) of severe problems in both shoulders and both sides of the neck. The prevalence was also higher among female viola players.6 68 Medical Problems of Performing Artists The Influence of Neck–Shoulder Pain on Trapezius Muscle Activity among Professional Violin and Viola Players: An Electromyographic Study Patrice Berque, B.Sc. (Hons), S.R.P., and Heather Gray, MSc., S.R.P. Mr. Berque and Ms. Gray are in the Division of Physiotherapy, Department of Physiotherapy, Podiatry and Radiography, Glasgow Caledonian University, Glasgow, Scotland, UK. This study was completed in partial fulfillment of Patrice Berque’s Bachelor of Science degree (Hons) in physiotherapy at Glasgow Caledonian University, Glasgow, Scotland. Presented at the Scottish Physiotherapists Research Workshop, Stirling, Scotland, April 2001, organized by the Scottish Board of the Chartered Society of Physiotherapists; at the annual conference of the Association of Chartered Physiotherapists in Occupational Health and Ergonomics, Edinburgh, Scotland, May 2001; and at the international conference, Health and the Performing Artist, Glasgow, Scotland, August 2001, organized by the British Performing Arts Medicine Trust, London, UK. Supported by Glasgow Caledonian University, and the Scottish Board of the Chartered Society of Physiotherapy for attendance to the conference. Address correspondence and reprint requests to: Mr. Patrice Berque, c/o Heather Gray, Division of Physiotherapy, Department of PPR, Faculty of Health, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4 0BA, Scotland UK. e-mail: . Playing-related Musculoskeletal Disorders and the Violin/Viola Player Caldron et al.3 attempted to explore the nature of these complaints, and concluded that the vast majority of PRMDs fell into four categories: overuse tendinitis; muscle cramps and occupational palsies; nerve entrapment syndromes; and bone, joint, and bursal injuries. Nevertheless, even in the absence of detectable physical pathology,12,13 there is some evidence to suggest that complex repetitive movements, involving prolonged static and dynamic loading of muscles, are contributory factors in producing PRMDs.10 This is particularly appropriate when the violinist’s or violist’s posture is considered: a raised left shoulder, the instrument supported on the left supraclavicular fossa, left rotation and side-flexion of the head, abduction and full external rotation of the left arm, left forearm supination, a dropped right shoulder, and internal rotation and abduction of the bowing arm with forearm pronation.10,14-18 Electromyographic Investigations on Violin Players Although many electromyographic (EMG) studies have used the upper trapezius muscle to gain information on muscle work during occupational work,19,20 few have focused on the effects of PRMDs and stressful conditions on the activity of this muscle in violin and viola players. Levy et al.21 used EMG analysis to compare muscle activities in the upper arm muscles of violin players (n = 15) with and without a shoulder rest under three conditions. The results revealed a significant reduction of the rectified EMG signals in the left trapezius (p < 0.03) and right sternocleidomastoid (p < 0.01) muscles when the shoulder rest was used. Nevertheless, the EMG data were not normalized, and did not therefore allow comparisons between subjects. Philipson et al.,22 more specifically, compared normalised, averaged, and rectified EMG results bilaterally on deltoid, upper trapezius (UT), biceps, and triceps muscles in nine professional violin players. Despite a small, unbalanced sample size between the PRMD and pain-free groups, and less-thanoptimal electrode placement (electrodes centered over the middle part of the muscle),19 they found that subjects affected by PRMDs produced significantly more muscle force than their unaffected counterparts for the right deltoid, the right biceps, and both left and right upper trapezius (p < 0.05). Psychological Stress and Muscle Hyperreactivity Performance-related anxiety, a playing-related health problem evidenced in the ICSOM survey by 16% of respondents as being a severe problem, cannot be ignored as another possible component that may affect the severity of existing PRMDs.5 Indeed, Flor et al.23 hypothesized that the development and maintenance of chronic musculoskeletal pain may be the result not only of physical causes but also of other psychological variables, suggesting that some individuals may be predisposed to respond to stress with a hyperreactivity of certain muscles. In addition, Moulton and Spence12 proposed that muscular hypertension may eventually lead to ischemia of the affected muscles, generating a pain–tension–pain cycle. Larsson et al.24 studied 76 workers (with long-standing unilateral neck pain and diagnosed chronic trapezius myalgia) using laser Doppler flowmetry to measure muscle blood flow, and surface EMG of both UT muscles during a fatiguing series of stepwise increased static loads. They concluded that the increased muscle tension on the painful side (p < 0.05) may be secondary to impaired microcirculation of the muscle (p < 0.05), and the consequent release of nociceptive substances, thereby maintaining the pain–tension–pain cycle.12,24