Association between elite swimmers' force production and 100 m front crawl inter-lap pacing and kinematics.

The present study aimed to analyse the associations between force production and 100 m front crawl inter-lap pacing and kinematics. Eleven elite male swimmers performed a 100 m front crawl maximal effort to collect 50 m lap time (T, s) and velocity (v, m·s) for pacing, stroke rate (SR), stroke length (SL) and stroke index (SI) as kinematic variables. A 30 s tethered effort allowed to determine the peak (F) and mean force (F) as force production variables. The relative change (Δ) between 50 m laps was also calculated for all measures. A paired sample -test was used to check differences between laps and Pearson correlation coefficients allowed to quantify the associations between force and remaining variables. The T increased from the first to the second lap (ΔT = 10.61%,  < 0.01, d = 2.68), while v (Δv = -5.92%,  < 0.01, d = 1.53), SR (SR = -6.61%,  < 0.01, d = 0.45) and SI (ΔSI = -4.92%,  = 0.02, d = 0.45) decreased. SL remained unchanged between laps (ΔSL = 1.07%,  = 0.66, d = 0.08). No associations were found between force production and most of Δ, with the only exception being the reasonable good association between F and Δv (r = 0.62,  = 0.04). Although both pacing and kinematics fall from the first to the second sections of a 100 m front-crawl effort, the swimmers who exhibit higher F show a more stable front crawl v between both 50 m laps.