The swimming start, which involves interactions with both water and air, has predominantly been studied primarily in terms of spatio-temporal parameters, while its motor control aspects have received limited attention. This study aims to investigate and compare the coordination patterns between the arm and trunk, as well as the thigh and trunk, in S9, S10, and S12 Paralympic swimmers using the continuous relative phase. The study included twenty-one Paralympic swimmers, and the results showed significant differences (p < 0.05) from spm1d (ANOVA) in both arm-trunk and thigh-trunk CRP among the three classes of swimmers. Significant differences were observed in the arm-trunk CRP during the initial (0–8% of time) and end (30–41% of time) parts of the block phase. Both of these two differences are from the comparison of S10 and S12. The thigh-trunk CRP also showed significant differences at the end of the block phase (35–41% of time) and during the flight phase before entry (58–61% of time). Significant differences were observed in post hoc tests between S9 and S10 and between S12 and S10 for the first significant difference. The second significant difference was found between S12 and S10. The results indicate that Paralympic swimmers classified as S9, S10, and S12 tend to exhibit distinct inter-segmental coordination patterns during the dive start. By recognizing different patterns of motor coordination, coaches and trainers can develop individualized training methods to optimize the start performance for swimmers with different impairments (different classifications) and maximize their competitive potential.

This study investigated upper-lower body coordination during the swimming start. Coupling angle mapping was applied to assess segmental dominance, coupling angle, and coupling angle variability across four dive-start phases in elite and sub-elite swimmers. Data were collected from twenty swimmers (ten elite and ten sub-elite), based on their three fastest maximal-effort dive starts. The continuous entry movement from air to water was captured in detail using a high-speed multi-camera system positioned above and below the water. Results demonstrated that coordination patterns varied across the four phases, with high similarity when the thigh dominated, such as during the flight phase. Notably, coordination during the on-block phase differed significantly prior to hand-off. Elite swimmers exhibited greater trunk dominance in the entry phase, facilitating a more horizontal dive-in, whereas sub-elite swimmers showed trunk dominance later, during the transition phase. In conclusion, the time required to reach a specific distance or phase does not necessarily indicate superior start performance. Swimmers must balance drag minimization during the dive-in trajectory with rapid entry to initiate stroking. All swimmers maintained a streamlined posture and predominantly employed thigh-dominant strategies, while variations in trunk-dominant coordination were observed during entry and transition phases. Occasional high coupling angle variability in elite swimmers may reflect individualized coordination strategies. These findings highlight the importance of individualised training to optimize start performance.

Para swimmers categorized as S10 and S12 are of particular interest due to their disability grading being closest to that of able-bodied swimmers, making them an ideal group for investigating disparities in limb coordination patterns. This study aimed to investigate whether S10 and S12 para swimmers, whose disability grading for movement and visual ability, respectively, were the closest to that of able-bodied swimmers, would differ in terms of the biomechanics of limb coordination. This study recruited twenty para swimmers (ten with minor limb absence (S10) in the hand and ten with minor visual impairment (S12)). Using panoramic video, the phase duration, stroke length, stroke rate, index of coordination, synchronization, and inter-limb coordination were digitized and compared in the context of a front-crawl sprinting test. The results showed a significantly different duration of the recovery phase for S10 para swimmers at the affected side, where a more random coordination pattern between arm and leg at the pull and push phases was statistically seen. The variation of the inter-limb coordination gradually increased for S10 para swimmers from hand entry to the end of push, but gradually reduced for S12 para swimmers. These results suggest that the same pace was achieved by different hand–leg coordination patterns according to their physical constraints. Consequently, the unique coordination patterns of different para swimmers from this study offer an opportunity to explore the adaptive strategies and biomechanical adjustments that enable optimal performance for para swimmers.