Associations between muscle strength, flexibility, and 50-meter freestyle swimming time

This study examined how land-based strength and flexibility relate to 50 m sprint performance in 12 competitive swimmers. Cadet swimmers (n = 7) averaged 13.3 ± 0.49 years of age, 167.0 ± 5.19 cm in height, and 58.7 ± 16.5 kg in body mass; junior swimmers (n = 5) averaged 15.4 ± 0.55 years, 176.0 ± 7.33 cm, 64.2 ± 5.81 kg, and 8.20 ± 1.64 years of training. Pearson correlations revealed that sprint time was moderately negatively associated with push-ups (r = -.38), sit-ups (r = -.63), and long jump (r = -.62), less so with shoulder flexibility (r = -.31), and essentially unrelated to sit and reach (r = -.03). Because long jump and shoulder flexibility were highly collinear (r = .78; VIFs > 7), shoulder flexibility was excluded from regression. An AIC-based stepwise model retained only age-group and sit-up performance, explaining 50% of variance in sprint time, F(2, 9) = 4.50, p = .044. Although the overall model was significant, neither predictor reached individual significance. These results underscore the multifactorial nature of swim speed and suggest that composite land-based assessments, rather than isolated field tests, offer more stable, interpretable sprint performance indices. Future research should employ larger, longitudinal designs and integrate water-based biomechanical measures.