The Influence Of Stroke Frequency In Front Crawl Coordination In Young Swimmers

Abstract

In front crawl, coordination is one of the main performance determinants that depend, among other factors, on the stroke frequency (SF). However, its influence on spatio-temporal coordination in young swimmers remains unclear. PURPOSE: To analyze the influence of SF on inter-arm coupling at maximal velocity in young swimmers. METHODS: 8 female swimmers (13.3±0.5yrs, 1.6±0.04m, 50.7±4.2kg) performed 3x50m at maximal velocity: (i) using their preferred SF (100%); (ii) 10% below (90%); and (iii) 10% above (110%). Velocity was controlled by a visual pacer (Pacer2Swim, Portugal) and the SF by a Tempo Trainer (Finis). One arm cycle was analyzed using ten anatomical landmarks identified by reflective markers and tracked using a 13-camera Qualisys setup (Qualisys AB, Sweden). The relative time spent in in-phase and anti-phase was calculated. Relative duration of the propulsive (pull and push phases) and non-propulsive (entry and catch and recovery) phases was computed for right and left upper limbs. One-way repeated measures ANOVA with Bonferroni post-hoc test were computed. RESULTS: Table 1 presents the results of the variables analyzed.Table 1: Mean ± SD values of phase and anti-phase and propulsive and nonpropulsive percentages of a stroke cycle for both right (Rprop and Rnonprop) and left (Lprop and Lnonprop) arms at three different SF.CONCLUSIONS: Time in anti-phase raised with increasing SF, evidencing that this adaptation to the task constraint results in a greater coupling between arms. For both imposed SF, a smaller relative time in propulsive phases was observed for the right arm. This fact suggests that the velocity maintenance was obtained due to a greater force application (rise in propulsive impulses per arm) at 90% and superior propulsive continuity (higher anti-phase) at 110%. The imposed constrains were preferably overcome by the dominant arm, which presented higher adaptability to control and drive the movement. Acknowledgements: FCT:DFRH-SFRH/BD/87780/2012