Monitoring In-Water and Dryland Interlimb Asymmetry of Young Competitive Swimmers: Insights Across a Training Macrocycle

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This study aimed to monitor the in-water and dryland interlimb asymmetry of young competitive swimmers throughout a full training macrocycle and verify possible associations with performance. Twenty-three young competitive swimmers (12.13 ± 0.74 years) were evaluated before (M1) and after (M2) a 16-week training macrocycle. The swimmers were timed at a 25 m front crawl (T25) and then evaluated in anthropometrics, mean peak (Fpeak) in-water forces and the shoulder internal rotator’s strength (IR) of dominant (D) and non-dominant (ND) limbs. The symmetry index was computed for both in-water (SyIwater) and dryland (SyIland) environments followed by the rate of force transfer (RFT) estimation. While the swimmers have grown in height, arm span and hand surface area, accompanied by an improvement in T25, the other variables remained unchanged after the 16 weeks. A significant and moderate association was found between FpeakD (r = −0.47) or FpeakND (r = −0.41) and T25, as well as between the IRD (r = −0.51) or IRND (r = −0.57) and T25 in M1. In M2, the non-dominant side gained relevance mostly in FpeakND, showing a significant and high association with T25 (r = −0.68), like the FpeakD (r = −0.69) and IRD (r = −0.53). Most of the individual plots (>80%) were under 30% of SyIwater, with the faster swimmer values between 10 and 30%. It can be concluded that a 16-week training macrocycle is not enough to change the young swimmers’ in-water and dryland symmetry, but this does not seem to affect their front crawl sprint performance.