A 4-Beat Kick Frequency May Optimize Consistency and Efficiency in 800 Meter Freestyle Swim Performance

Introduction: This exploratory study examined the effects of kick frequency (KF) on performance, biomechanical, physiological, and psychophysiological variables to determine optimal performance in an 800 m long course freestyle swim. Methods: Six international-level swimmers completed 5 x 100 m pacing efforts at 2-, 4-, and 6-beat KF. Multiple one-way repeated measures ANOVAs compared effects of KF on target time coefficient of variation (TTCV), stroke rate (SR), stroke length (SL), heart rate (HR), caloric energy expenditure (EE), and rate of perceived exertion (RPE). Results: A significant KF effect was found for RPE [F(2,10) = 17.143, p = .009, η2 = .774]. RPE was greater in the 6-beat (14.43 ± 1.85) vs. 4-beat (12.03 ± 0.64; p = .027) and 2-beat (11.23 ± 1.78; p = .024) KF. The effect of KF on TTCV was significant [F(2,10) = 4.090, p = 0.050, η²p = 0.450], but while the 4-beat KF demonstrated the lowest mean variability, the sensitivity of pairwise comparisons failed to detect where significance lay. No significant effects were found for HR, EE, SR, or SL (p > .05). Conclusions: Coaches may consider the 4-beat KF as a hybrid advantage since it requires less metabolic cost than the 6-beat KF, allows for higher velocity without a proportional increase in EE or RPE, promotes pacing consistency, and provides an efficient balance between SL and SR.