A Correlational Analysis between the Rate of Force Development among the Arm Stroke, the Leg Kick, the Full Stroke and Short Distance Front Crawl Speed in Highly Trained Swimmers

This study aimed to analyze sex differences in the rate of force development (RFD) among the arm stroke only (As), the leg kick only (Lk), and the full stroke (Fs) through the 30-s front crawl tethered-swimming (TS) test, and to discuss the correlation between RFD variables and short-distance front crawl speed in the force-time (F-t) curve across different sexes. Sixteen male and fourteen female highly trained swimmers (age: 19.7 ± 3.27 years) performed the TS test under three conditions: As, Lk, Fs, as well as a 25-m front crawl test. The As, Lk, Fs of the peak RFD per 5 s (RFDave), and maximum value of the peak RFD every 5 s (RFDmax) had highly significant correlation with V25, V50, and V100 (V25−V100). Notably, the Fs of the male RFD and the As of the female RFD showed particularly strong correlations with V25−V100. It was also observed that there were sex-specific disparities in the RFD indices associated with the As, Lk, and Fs phases of swimming. The findings indicate that the RFD within the F-t curve is a valuable variable for assessing the capacity to generate propulsive force in water. Sex factors affect the relationship between RFDave, RFDmax, and short-distance front crawl speed in swimming. Coaches should fully consider sex differences when training for swimming propulsive force.