Sex Differences in Dynamic Closed Kinetic Chain Upper Quarter Function in Collegiate Swimmers

Context: Upper quarter injuries have a higher incidence in female swimmers; however, to date, there are few ways to assess the basic functional ability of this region. The upper quarter Y balance test (YBT-UQ) may assist in this process because it was developed to provide a fundamental assessment of dynamic upper quarter ability at the limit of stability. Objective: To examine how sex affects performance on the YBT-UQ in swimmers. Design: Cohort study. Patients or Other Participants: Forty-three male and 54 female National Collegiate Athletic Association Division I college swimmers were recruited preseason. Main Outcome Measure(s): We measured YBT-UQ performance for the left and right limbs in the medial, inferolateral, and superolateral directions. The maximum score for each direction was normalized to upper extremity length. The average of the greatest normalized reach scores in each reach direction was used to develop a composite score (average distance in 3 directions/limb length [LL] x 100). To examine reach symmetry between sexes, the difference in centimeters between the left and right sides was calculated for each reach direction prior to normalization. Statistical analysis was conducted using an independent-samples t test (P<.05). Results: Average scores in the medial (women: 92.5 +/- 7.4% LL, men: 100.0 +/- 8.7% LL; P<.01) and inferolateral (women: 85.6 +/- 10.3% LL, men: 89.8 +/- 10.8% LL; P = .05) directions and composite score (women: 83.4 +/- 8.3% LL, men: 88.3 +/- 8.9% LL; P<.01) were higher in men than in women. No differences were observed for reach symmetry in any direction. Conclusions: Performance on several YBT-UQ indices was worse for female than male collegiate swimmers. These results may have implications for the use of preseason and return-to-sport testing in swimmers as a measurement of upper quarter function and symmetry.