Effect of Match Play on Shoulder Strength in Amateur Rugby Union Players

Zelinski, S, Manvell, JJ, Manvell, N, Callister, R, and Snodgrass, SJ. Effect of match play on shoulder strength in amateur rugby union players. J Strength Cond Res 35(9): 2584-2590, 2019-The purpose of this study was to determine the effect of match play on shoulder internal rotation (IR) and external rotation (ER) strength in amateur Australian rugby union players. Maximal isometric shoulder IR and ER strength was measured in 18 male players using hand-held dynamometry before match, at half-time, after match, and 1, 3, and 7 days after match. Match stress was measured intrinsically (rating of perceived exertion) and extrinsically (number of shoulder events). Linear mixed regression modeling determined differences in strength measures while exploring possible confounders, including history of pain, pain on testing, player position, exposure, height, body mass, and body mass index. From the models, IR strength decreased from before match to after match (adjusted mean difference 1.96 kg; 95% confidence interval [CI]: 0.63-3.29, p = 0.004), 1 day after match (2.47; 1.14-3.80, p < 0.001), and 3 days after match (1.75; 0.42-3.09, p = 0.010). External rotation strength decreased from before match to half-time (adjusted mean difference 1.54 kg, 95% CI: 0.65-2.42, p = 0.001), but no other time points demonstrated significant changes in ER strength compared with before match. None of the possible confounding variables significantly affected strength changes over time. Rugby union match play is associated with reduced shoulder strength, particularly IR. Future research is required to establish whether strength changes are associated with shoulder pain and injury.