## 4 Discussion  
This study utilized CRP analysis to evaluate the arm-trunk and thigh-trunk coordinates of Paralympic swimmers. The objective was to understand the biomechanics of swimming start for Paralympic swimmers. These results show that during the start of swimming, the coordination between segments is related to the disability level. The arm-trunk CRP (Figure 5a) shows that S12 swimmers in the first 20% of the time are significantly larger (\(p\) = 0.013) than the other two groups. These swimmers have difficulty executing their movements with external focus and visual feedback. It has been shown that visual cues can aid in timing movements and coordinating body segments [28] and visual impairment will affect the swimmer's ability to monitor their cadence [40], and S12 swimmers are unable to accurately identify the external environment through visual cues. Thus, S12 swimmers may rely more on proprioceptive feedback to guide their movements. This can lead to a premature focus of attention on the arm in the block phase from 0% to 20% in Figure 5, causing S12 swimmers to be more likely to extend their arms earlier compared to swimmers with normal vision (S9 and S10). Additionally, the analysis of the thigh-trunk CRP for the lower limbs (Figure 6) revealed that the S10 and S9 swimmers used the anti-phase coordination mode at the initial block phase (0-12%), while the S12 swimmers' thigh and trunk were in the intermediate-phase coordination mode during the same time duration. More likely, they do not require the level of trunk extension as much as the other two groups. This is because their flight time, as indicated in Table 2, is shorter. Their primary objective is to enter earlier rather than cover a greater distance, suggesting they may not rely too much on trunk strength before 12% of the time domain. S12 swimmers exhibited an in-phase coordinated mode during 36% to 65% of the period. Considering the information presented in Table 2, this phase can be identified as the transition point. A study by [PERSON] et al. showed that visually impaired swimmers often earlier to reduce the risk of deviating into the lane beside them [41]. This \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Phase Duration** & **S9** & **S10** & **S12** & \(p\)**-Value** \\ **(\%)/Groups** & & & & \\ \hline Block phase & 40.33\% \(\pm\) 2.30 & 38.83\% \(\pm\) 1.75 & 38.07\% \(\pm\) 4.46 & 0.219 \\ Flight phase & 21.35\% \(\pm\) 1.23 & 22.04\% \(\pm\) 2.71 & 14.39\% \(\pm\) 9.13 & 0.000 * \\ Entry water phase & 20.56\% \(\pm\) 1.66 & 23.38\% \(\pm\) 1.93 & 25.24\% \(\pm\) 1.99 & 0.856 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Percentage of time for the four phases (mean \(\pm\) SD) (* \(p\) < 0.05). is similar to our finding that S12 swimmers exhibit an arm-leading motion at the start of the block phase, suggesting a potential early entry strategy. Previous studies have suggested that swimmers with lower levels of disability may perform better during the start [42]. Accordingly, the in-phase coordination mode for S9 during the initial block phase (0-5%), in which S10 and S12 showed significantly different arm-trunk CRP (\(p\) = 0.012) of intermediate-phase coordination mode, may be attributed to their more severe physical disabilities compared to the S10 and S12 swimmers. The more severe physical disabilities of S9 swimmers affected their inter-segmental coordination, leading to a limited ability to fully extend their arms. Additionally, due to the higher level of disability of S9 in the lower limbs, they may have a greater need to maintain their balance, further limiting their ability to fully extend their segments. This may explain why the thigh-trunk CRP of S9 is significantly lower than S10 at the end of block phase just before toe-off. The results of the study showed that S10 swimmers had larger CRP for both their arm-trunk and thigh-trunk during the end of the block phase (35-41%) compared to the other two groups.