## 4 Discussion  
### Interpretation of Results  
To verify the effectiveness of tube training, this study first confirmed that tube training and SF-ex had a significant immediate effect on the AbH and FDB through a crossover study using ultrasound echo. Next, a randomized controlled trial targeting long-distance runners showed that both tube training and SF-ex equally improved the toe grip strength, toe gap strength, and RSI. In a previous study of 23 competitive runners, a 5-week toe flexor muscle training intervention including SF-ex resulted in a 16% increase compared to baseline [21]. In this study, tube training led to an increase of 20.6% in the toe grip strength, 18.7% in the toe gap strength, and 9.5% in the RSI. SF-ex led to an increase of 16.1% in the toe grip strength, 9.9% in the toe gap strength, and 4.2% in the RSI. Therefore, this training was able to demonstrate results that were equivalent to or better than those of previous research. Although the SF-ex has shown a certain level of effectiveness, the issues that need to be resolved include the fact that it is difficult to learn, the load cannot be adjusted, and it does not involve movement of the ankle joint. In contrast, the tube training method allows one to feel the resistance of the tube and change the intensity, so it has the potential to be easily implemented according to the individual's toe function. In addition, tube training involves the movement of the ankle joint. In the plantar flexion position of the ankle joint, the interphalangeal (IP) joint is extended due to the tenodesis action of the foot. This is because the anatomical differences between the extrinsic and intrinsic muscles of the foot cause the flexion and extension of the IP joint to change as the ankle joint moves between plantar and dorsal flexion. The extrinsic muscles of the foot attach to the distal phalanges, but the AbH and FHB muscles stop at the base of the first metatarsal bone via the sesamoid bone, and the FDB muscle stops on the lateral side of the base of the second to fifth metatarsal bones [39]. Therefore, while the extrinsic muscles have a flexion action on the distal interphalangeal (DIP) joint, the IFM does not have a flexion action on the DIP joint. Tube training applies force in the direction of MTP joint extension. When the tube is at its maximum extension and resistance is at its strongest, MTP joint flexion force is exerted. Tube training may have effectively trained the IFM by maintaining MTP joint flexion against the resistance of the tube while the IP joint was extended in the plantar flexion position of the ankle joint. In SF-ex, no force is applied in the direction of MTP joint extension, so these types of loads are not applied, and they would be difficult to understand in voluntary isometric \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**Within-Group Differences**} \\ \cline{3-6}  & \multicolumn{1}{c}{**Pre-**} & \multicolumn{1}{c}{**Post-**} & \multicolumn{1}{c}{**Difference**} & \multirow{2}{*}{\(p\)} & **Cohen’s d** \\  & & & & **[95\% CI]** & & **[95\% CI]** \\ \hline \multirow{3}{*}{Toe grip strength} & Tube training & 19.4 \(\pm\) 4.3 & 23.3 \(\pm\) 3.6 & 3.98 & 0.002 ** & 1.37 \\  & & & [1,91, 6.05] & & [0.48, 2.24] \\  & SF-ex & 20.1 \(\pm\) 4.9 & 23.4 \(\pm\) 4.4 & 3.24 & 0.019 * & 0.98 \\  & & & [0.69, 5.80] & & [0.15, 1.76] \\  & Tube training & 3.2 \(\pm\) 0.9 & 3.8 \(\pm\) 0.9 & 0.60 & 0.002 ** & 1.37 \\  & & & [0.29, 0.91] & & [0.48, 2.24] \\  & & & & 0.37 & 0.20 & 0.46 \\  & & & & [\(-\)0.24, 0.97] & & [\(-\)0.24, 1.14] \\  & & & & 0.22 & 0.046 * & 0.73 \\ RSI & & & & 0.01, 0.44] & & [0.01, 1.42] \\  & SF-ex & 2.41 \(\pm\) 0.44 & 2.51 \(\pm\) 0.62 & 0.10 & 0.396 & 0.30 \\  & & & & [\(-\)0.16, 0.36] & & [\(-\)0.38, 0.96] \\ \hline \hline \end{tabular} Data presented as mean \(\pm\) SD. RSI = reactive strength index; 95% CI = 95% confidence interval. * \(p\) < 0.05; ** \(p\) < 0.01.  
\end{table} 
Table 3: Changes in toe function pre- and post-intervention within the group. contraction.