Bilateral scapular kinematics, asymmetries and shoulder pain in wheelchair athletes

Background Shoulder pain is the most common complaint for wheelchair athletes. Scapular orientation and dyskinesia are thought to be associated with shoulder pathology, yet no previous studies have examined the bilateral scapula kinematics of wheelchair athletes during propulsion. Research question To examine bilateral scapular kinematics of highly trained wheelchair rugby (WR) players and any associations with self-reported shoulder pain during everyday wheelchair propulsion. Methods Ten WR players (5 with shoulder pain, 5 without) performed 2 × 3-minute bouts of exercise in their everyday wheelchair on a wheelchair ergometer at two sub-maximal speeds (3 and 6 km∙h-1). During the final minute, 3D kinematic data were collected at 100 Hz to describe scapulothoracic motion relative to each propulsion cycle. Instantaneous asymmetries in scapular orientation between dominant and non-dominant sides were also reported. Differences in scapular kinematics and propulsion asymmetries were compared across shoulders symptomatic and asymptomatic of pain. Results An internally rotated, upwardly rotated and anteriorly tilted scapula was common during wheelchair propulsion and asymmetries ≤ 14° did exist, yet minimal changes were observed across speeds. Participants with bilateral shoulder pain displayed a less upwardly rotated scapula during propulsion, however large inter-individual variability in scapular kinematics was noted. Significance Scapular asymmetries are exhibited by wheelchair athletes during wheelchair propulsion, yet these were not exacerbated by increased speed and had limited associations to shoulder pain. This suggests that propulsion kinematics of highly trained athletes may not be the primary cause of pain experienced by this population

Sprint performance and propulsion asymmetries on an ergometer in trained high- and low-point wheelchair rugby players

The purpose of this study was to examine the propulsion asymmetries of wheelchair athletes whilst sprinting on an instrumented, dual-roller ergometer system. Eighteen experienced wheelchair rugby players (8 low-point (LP) (class ≤1.5) and 10 high-point (HP) (class ≥2.0)) performed a 15s sprint in their sports wheelchair on the instrumented ergometer. Asymmetry was defined as the difference in distance and power output (PO) between left and right sides when the best side reached 28m. Propulsion techniques were quantified based on torque and velocity data. HP players covered an average 3m further than the LP players (P=0.002) and achieved faster sprint times than LP players (6.95 ± 0.89 vs. 8.03 ± 0.68 s, P=0.005) and at the time the best player finished (5.96 s). Higher peak PO’s (667 ± 108 vs. 357 ± 78 W, P=0.0001) and greater peak speeds were also evident were for HP players (4.80 ± 0.71 vs. 4.09 ± 0.45 m·s-1, P=0.011). Greater asymmetries were found in HP players for distance (1.86 ± 1.43 vs. 0.70 ± 0.65 m, P=0.016), absolute peak PO (P=0.049) and speed (0.35 ± 0.25 vs. 0.11 ± 0.10 m·s-1, P=0.009). Although HP players had faster sprint times over 28m (achieved by a higher PO), high standard deviations show the heterogeneity within the two groups (e.g. some LP players were better than HP players). Quantification of asymmetries is not only important for classifiers but also for sports practitioners wishing to improve performance as they could be addressed through training and/or wheelchair configuration