## 4 Discussion  
This study aimed to monitor young swimmers' in-water and dryland interlimb asymmetry throughout a full training macrocycle and to verify possible associations with performance. The results showed that young swimmers remained asymmetrical over the training macrocycle in both in-water and dryland environments without impairing performance. Although in-water and dryland symmetry were not associated with the performance, the contribution of the D and ND upper limbs gained relevance later in the macrocycle. An increase in physical attributes along with improved performance (e.g., T25) was observed during the 16 weeks that composed the first training macrocycle of the season. Growth spurts are common in young swimmers and can naturally contribute to changes in technique and performance [21, 23]. An increased AS and HSA are especially beneficial for swimmers as they can enhance stroke length [29]. Also, the increased BM, when not solely from adipose tissue, can indicate muscular development [30]. This combination of growth and targeted physical adaptations could collectively enhance overall performance, supporting the rationale that young swimmers benefit from training programs aligned with their natural growth cycles. Interestingly, despite notable increases in anthropometric variables, no changes were observed in Fpeak, IR or even in the RFT. The unchanged Fpeak of young swimmers over prolonged periods [20] or even after a training session [31] can be found in the swimming scientific literature. As this was the first macrocycle of the season, other key aspects (e.g.,  
Figure 3: Individual dot plots from the link between T25 and in-water Syl in evaluation moment 1 (**A**) and evaluation moment 2 (**B**). The green area outlined by a dotted line represents the cut-off value of 30% of the in-water symmetry index. Syl, symmetry index; and T25, 25 m time. Figure 2: Correlation matrix between T25 and both in-water and dryland variables in evaluation moment 1 (**A**) and evaluation moment 2 (**B**). T25, 25 m time; Fpeak, mean peak force; Syl, symmetry index; IR, shoulder internal rotator strength; RFT, rate of force transfer; D, dominant; ND, non-dominant; * \(p<0.05\); ** \(p<0.01\)**. technique refinement) may have taken the primary role in each training session, not leaving space for specific force development. The lack of change in in-water force and dryland strength indicate that young swimmers may require a longer period of training to manifest their adaptations in propulsion or need to target specific in-water and dryland strength training to obtain neuromuscular adaptations and transfer those to the water in a shorter time frame. It is unclear if the same could happen in the following macrocycles of the season or even if these results could be similar until age cohorts where swimmers are near their maximum strength development. So, those are important questions that need to be answered and can be the focus of further studies. The \(\text{Syl}_{\text{water}}\) and \(\text{Syl}_{\text{land}}\) also remained unchanged after the 16 weeks of training, leaving swimmers to be asymmetrical while swimming front crawl (\(\text{Syl}_{\text{water}}\approx 18\%\)). The unchanged \(\text{Syl}\) in these swimmers suggests that anthropometric adaptations alone, such as increases in arm span and hand surface area, may not be sufficient to correct or improve bilateral force symmetry. Without targeted training, specifically aiming at addressing imbalances, young swimmers may not attenuate the existing asymmetries. In fact, work with asymmetries should be part of coaches' and athletes' daily routine as the nature of dominance persists in sports [6]. In this case, an asymmetric pattern in these swimmers was not harmful because they were still able to improve their performance from M1 to M2. Although the 16 weeks at the beginning of the season were not enough to elicit changes, a couple of associations were found between the T25 and in-water or dryland variables.