Inter-Limb Coordinative Structure in a 200 m Front Crawl Event

The Index of Coordination has been currently used as a tool that measures the inter-arm lag time between propulsive phases in front crawl swimming. The aim of the present study was to assess the inter-arm coordinative structure during a 200m front crawl maximal effort, as well as to understand its interplay with the stroking parameters. One complete arm stroke cycle, without breathing, was digitized and analysed the relative duration of the different phases and identified the model of arm coordination by using the Index of Coordination in each length of 50m of the 200m front crawl. A one way repeated measures ANOVA, with Tukey post-hoc test was used to compare all the variables, and Pearson correlation coefficients were computed between Index of Coordination and the biomechanical (velocity, stroke rate, stroke length) and coordinative parameters (p<0.05). Results showed an increase in the relative duration of the propulsive phases, which induced an increase in the Index of Coordination as fatigue developed in relation to a decrease in velocity, stroke rate and stroke length. Additionally, Index of Coordination was inversely related with entry/catch (r=-0.78) and the non-propulsive phases (r=-0.97), and positive related with the pull (r=0.54), push (0.78) and propulsive phases (r=0.97). The results highlighted that, in fatigue stages, swimmers tend to increase their propulsive continuity, corresponding to a reduction of the non-propulsive lag time between the two arms’ propulsive actions.