GENDER DIFFERENCES IN DOUBLE-LEG KICKING

Connaboy, C., Coleman, S., & Sanders, R. H. (2012). ** Gender differences in heave and pitch phase relationships in maximal undulatory underwater swimming. ** Presentation 1917 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

This study examined gender differences in the relationship between the mean absolute relative phase of the heaving and pitch movements of the end-effectors with the production of maximal undulatory underwater swimming velocity in skilled swimmers (M = 8; F = 9; ~16.9 years). Ss swam three trials of maximal double-leg kicking to collect six cycles of video data. 2D kinematics were analyzed from the digitized motions of the wrist, shoulder, hip, knee, ankle, and 5th metatarsal phalangeal joint centers. Continuous relative phase was determined from the phase angles of vertical heave motions and pitch angle of the end-effector. The mean absolute relative phase of the heaving and pitch was calculated from the continuous relative phase using circular statistics. The relationships between the cycle frequency of the end-effector (5th MPJ), cycle length (distance travelled by the hip marker per cycle), and the average velocity of the hip marker per cycle to the mean absolute relative phase of the heaving and pitch were determined using Pearson’s correlation coefficient.

There were no significant differences in cycle frequency, cycle length, or hip velocity by gender. Mean absolute relative phase of the heaving and pitch (F = ~117.4; M = ~118.9) also showed no difference by gender. Correlation coefficients showed moderate relationships between mean absolute relative phase of the heaving and pitch and cycle frequency (F r = -0.553; M r = 0.597). Female swimmers showed a large correlation with cycle length (r = 0.704) compared to none for males (r = 0.182). All correlations between mean absolute relative phase of the heaving and pitch and hip velocity were small and non-significant.

**Implication**. Mean absolute relative phase of the heaving and pitch was considerably different to a theoretical 75° optimal phase relationship. The differences in the correlation coefficients suggest males and females adopt different coordination patterns to achieve maximal undulatory underwater swimming (double-leg kicking).