Comparison of Bilateral Asymmetry in Pelvic Tilt and Pelvic Obliquity between Freestyle and Butterfly Swimmers

Abstract

The purpose of the present study was to compare bilateral asymmetry in pelvic tilt and pelvic obliquity between freestyle and butterfly swimmers. A total of twenty national-level male swimmers participated in the study and were divided into two groups: freestyle swimmers (n = 10) and butterfly swimmers (n = 10). Bilateral asymmetry was assessed using the BTS G-Sensor during a 15-meter walk test. Interlimb asymmetry was calculated using the equation: (Max − Min) ÷ Max × 100. Descriptive statistics including mean, standard deviation, and standard error of the mean were calculated, and an independent samples t-test was used to determine differences between groups. Results indicated that pelvic tilt asymmetry was 31.59% (SD = 22.13) for freestyle swimmers and 27.60% (SD = 12.68) for butterfly swimmers, with no statistically significant difference between groups (t = 0.49, p > 0.05). However, pelvic obliquity asymmetry was 3.12% (SD = 3.76) in freestyle swimmers and 7.77% (SD = 5.34) in butterfly swimmers, showing a statistically significant difference (t = −2.25, p < 0.05). The findings suggest that although pelvic tilt asymmetry is similar between the two swimming strokes, butterfly swimmers exhibit greater pelvic obliquity asymmetry, which may be attributed to the biomechanical demands of the butterfly stroke.