(45) ISOMETRIC SHOULDER FORCE IN FEMALE AND MALE NCAA SWIMMERS

The Athletic Shoulder (ASH) test was developed to measure force across the shoulder girdle for assessing and monitoring isometric strength during recovery in athletes. To our knowledge, there have been a few studies conducted on rugby, baseball, and volleyball, but none have conducted the ASH test in collegiate swimmers.

Purpose: To describe shoulder girdle force production in the “Y” position in men and women in prone and supine positions in the left and right arm and to assess differences in shoulder force production anteriorly and posteriorly in the “Y” position between collegiate male and female swimmers.

Methods: National Collegiate Athletics Association Division I male (N=22, 21.0 ± 1.4 years, 78.5 ± 7.3 kg) and female swimmers (N=23, 20.3 ± 1.6 years, 69.6 ± 7.6 kg) participated in this cross-sectional study. Following a standardized warm-up, participants completed three bilateral maximal isometric contractions on dual force platforms (PASCO Scientific, Roseville, CA) measured at 1000 Hz with should abducted at 135˚ (i.e., “Y”) in the prone and supine positions with at least 60 seconds rest between. Peak isometric force was extracted for each trial, and mean force of all three trials was calculated for analysis. Data were analyzed for Gender-by-Position (prone vs. supine) interactions within each arm, and post-hoc tests were conducted using a Bonferroni adjustment (α=0.05). Effect sizes were calculated using Cohen’s d.

Results: For the left arm in the prone position, men produced 109.7 ± 24.5 N and women produced 73.6 ± 20.9 N. For left arm supine position, men produced 74.0 ± 16.6 N and women produced 54.8 ± 12.6 N. For right arm in prone position, men produced 114.8 ± 21.9 N and women produced 74.8 ± 21.8 N. For right are in supine position, men produced 77.1 ± 17.0 N and women produced 55.7 ± 11.9 N. Significant Gender-by-Position interactions were found for right (F_1,43=15.1, P< 0.001) and left arms (F_1,43=11.4, P=0.001). Post-hoc tests revealed similar patterns were observed for both arms. Men produced more force than women in each position (P< 0.01) and all athletes produced greater force in the prone compared to supine position (P< 0.01). In men, magnitude of difference (d) between prone and supine force was 2.07 for right and 1.94 for left arms. In women, this difference was 1.41 for right and 1.24 for left arms.

Conclusions: This is the first study to report descriptive data for the ASH test in collegiate swimmers. It was found that men produced a significant more force in both the prone and supine positions for both the right and left arm compared to women in the same position. Furthermore, both men and women produced more force in the prone position than in the supine position in both the right and left arms. Lastly, the magnitude of difference between prone and supine force production in men and women show larger differences for men compared to women. PRACTICAL APPLICATIONS: Practitioners can use the descriptive data shown here as normative baseline to compare their athletes’ data. The magnitude differences between supine and prone position could potentially relate to shoulder instability. Future research should be conducted to analyze the ratios between anterior and posterior shoulder force production and the relationship to injury risk.

Acknowledgements: None