Torso and bowing arm 3D joint kinematics of elite cellists

BackgroundSeveral large cohort studies of musicians have consistently reported a high prevalence of performance-related musculoskeletal disorders (PRMDs) amongst cellists. Highly repetitive movements and sustained positions of shoulder abduction and flexion in cello bowing can cause excessive physical loading of not only the muscles and tendons, but also to the bursae, ligaments and joints of the shoulder and the musculature employed to control the cervical and thoracic regions; this ultimately can lead to cumulative microtrauma and/or inflammation. There is a need to examine and quantify normative movements during cello playing to gain insight into potential causal factors for PRMDs in cellists. We quantified torso kinematics and right shoulder internal rotation in a group of experienced cellists during real-time performance of a set piece under contrasting sound volume conditions using 3D motion capture analysis. MethodsThirty-one professional and advanced student cellists performed a C major scale three times at two different volume levels in randomized order, with tempo regulated by a metronome. Torso and arm retroreflective markers and virtual marker trajectories representing the elbow and wrist processes were used to generate 3D computer models of three anatomical body segments. Two-way ANOVA were performed for each of the eight joint degrees of freedom, with playing on each of the four strings (C, G, D, A) and the two contrasting volume conditions as factors. ResultsSignificant effects were observed for both the string and/or volume conditions across all torso, shoulder and elbow kinematic degrees of freedom (p<0.05). The torso was consistently positioned by all participants in left rotation from the beginning of the scale, increasing at its apogee. During the loud playing condition, mean flexion, internal rotation and abduction ranges of the shoulder increased when playing at the tip of the bow on the A string (p<0.001), and a combination of torso flexion, right lateral flexion and left rotation was also observed.Conclusionsellists use highly consistent movement patterns to cross strings and regulate volume levels during fundamental bowing actions. There are clinical and pedagogical implications for the consistently static left rotated torso postures and high degree of combined shoulder flexion and internal rotation observed in this group of cellists.