Lateral dominance and (as)symmetry in 50 m all-out front crawl

The current study verified the side dominance and the symmetry index effect over the stroke phase's duration and coordination in a 50 m front crawl all-out test; and the correlations between the symmetry index and performance in the 50 m all-out front crawl test. Seventeen swimmers performed a 50 m front crawl all-out test. Sagittal underwater video analyses were performed. Lateral dominance was identified. Symmetry index was calculated for the bilateral parameters. Comparisons of the stroke phase's duration and index of coordination were performed (p ≤ 0.05 level). No difference between dominant and non-dominant sides was identified for the stroke phase's duration (trivial and small effects sizes were identified). Regarding the symmetry index, entry and catch (11.2), pull (18.3), and recovery (29.8) duration, and index of coordination (52.3) were outside of the -10 to 10 limits of symmetry, with asymmetry to the non-dominant side. The results demonstrated that swimmers present symmetry for the entry and catch, and push phases. Asymmetries were observed for pull, recovery, propulsive and non-propulsive phases, and coordination. No correlation between the indices and performance was identified. Different interpretations regarding asymmetries in relation to inferential statistics and cutoff values must be considered.