Factors affecting flutter kicking speed in women who are competitive and recreational swimmers

The purpose of this study was to determine the relationships between possible predictive measures of a 50 m front crawl swimming and a 22.86 m flutter kicking speed. Ten women who were National Collegiate Athletic Association Division I collegiate swimmers and 10 women who were recreational swimmers (mean +/- SD = 20.6 +/- 1.6 years; 66.7 +/- 10.3 kg; 166.7 +/- 8.8 cm) volunteered for the study. Anthropometric measures were obtained including height, leg length, lower leg length, and foot length. Ankle flexibility was assessed by measuring ankle plantar flexion and ankle inversion. Lower body power was measured using a vertical jump. Swimming and kicking speed were measured as the time to complete a 50 m front crawl and a 22.86 m flutter kick, respectively. Significant moderate correlations were demonstrated between ankle plantar flexion and flutter kicking speed (r = 0.509); age and 22.86 m kick time (r = 0.608); age and 50 m swim time (r = 0.476); and 50 m swim time and 22.86 m kick time (r = 0.790). No significant correlations were observed between any of the anthropometric measurements or vertical jump power with either kicking or swimming speed. As anecdotally noted by swim coaches over the years, this study provides some actual data showing that ankle flexibility significantly influences flutter kick capability. Surprisingly, vertical jump power and body size were not strong predictors of kicking or swimming speed in this group of subjects. Strength and conditioning coaches, swim coaches, and athletes should evaluate and carefully develop ankle flexibility to positively contribute to kicking capabilities.