Is being a regular player with fewer teammates associated with musculoskeletal pain in youth team sports? A cross-sectional study

BACKGROUND Musculoskeletal pain (MSP) is a commonly reported symptom in youth sports players. Some sports-related risk factors have been reported, but previous studies on extrinsic risk factors did not focus on management of team members (e.g., regular or non-regular players, number of players) for reducing sports-related MSP. This study aimed to examine the association of playing status (regular or non-regular players) and team status (fewer or more teammates) with MSP in youth team sports. METHODS A total of 632 team sports players (age: 12-18 years) in public schools in Unnan, Japan completed a self-administered questionnaire to determine MSP (overall, upper limbs, lower back, and lower limbs) and playing status (regular or non-regular players). Team status was calculated as follows: teammate quantity index (TQI) = [number of teammates in their grade]/[required number of players for the sport]. Associations between the prevalence of pain and joint categories of playing and team status were examined by multivariable-adjusted Poisson regression. RESULTS A total of 272 (44.3%) participants had MSP at least several times a week in at least one part of the body. When divided by playing or team status, 140 (47.0%) regular and 130 (41.7%) non-regular players had MSP, whereas 142 (47.0%) players with fewer teammates (lower TQI) and 127 (41.8%) players with more teammates (higher TQI) had MSP. When analyzed jointly, regular players with fewer teammates had a higher prevalence of lower back pain compared with non-regular players with more teammates (21.3% vs 8.3%; prevalence ratio = 2.08 [95% confidence interval 1.07-4.02]). The prevalence of MSP was highest in regular players with fewer teammates for all other pain outcomes, but this was not significant. CONCLUSION Regular players with fewer teammates have a higher risk of lower back pain. Future longitudinal investigations are required.