## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multicolumn{1}{c}{} & \multicolumn{2}{c}{**Kinematic**} & \multicolumn{2}{c}{**Kinetic**} \\ \hline \multirow{2}{*}{CON phase} & \multirow{2}{*}{Ankle joint (\({}^{\circ}\))} & Joint angular velocity (rad/s) & \
\begin{tabular}{c} Normalized \\ ground reaction force Fz \\ \end{tabular} &
\begin{tabular}{c} Mechanical \\ work (J) \\ \end{tabular} \\ \hline Sol RMS EMG & \(-0.011\) & \(-0.072\) & \(-0.404\) & \(-0.327\) \\  & (0.952) & (0.684) & (0.021) & (0.056) \\ MG RMS EMG & \(0.490\)\({}^{\star}\) & \(-0.065\) & \(-0.041\) & \(0.040\) \\  & (0.004) & (0.726) & (0.812) & (0.948) \\ ECC phase & & & & \\ Sol RMS EMG & \(0.013\)s & \(-0.281\) & \(-0.153\) & \(-0.560\)\({}^{\star}\) \\  & (0.959) & (0.113) & (0.417) & (0.001) \\ MG RMS EMG & \(0.247\) & \(-0.199\) & \(0.058\) & \(-0.127\) \\  & (0.180) & (0.276) & (0.751) & (0.490) \\ \hline \hline \end{tabular} Abbreviations: RMS EMG, root mean square electromyography; CON, concentric; ECC, eccentric; TA, tibialis anterior; SOL, soleus; MG, gastrocnemius medialis; LG, gastrocnemius lateralis. Correlations are presented as r\({}_{\text{s}}\) values, with the associated \(p\) values in parentheses. \({}^{\star}\) means significant.  
\end{table} 
Table 3: Spearman rank correlation coefficients between the EMG results of four leg muscles and the kinetic and kinematic characteristics during the one-legged heel-raise exercise. may be beneficial to ankle joint stability [25]. Such augmented co-activation in a repaired leg is consistent with that identified in a study involving bilateral hopping performed by patients years after the surgical repair of a torn Achilles [26]. This implies that such augmented coactivation, which jeopardizes ankle plantarflexion torque production, may be observed through the early to late stages of rehabilitation if early physiotherapy after the Achilles tendon rupture does not include soleus muscle training. Explosive strength training and eccentric resistance training have been shown to efficiently suppress the antagonist muscles and increase the maximal voluntary torque of the plantar-flexor muscles [27; 28]. Eccentric resistance training was additionally found to increase the muscle fascicle with increasing magnitude [29], which may be beneficial for reducing the muscle fascicle shortening that occurs as part of the gastrocnemius muscle atrophy seen after an Achilles tendon rupture [6]. The results of this part of the current study indicate the advisability of incorporating supplementary eccentric strengthening of the plantarflexor muscles into the rehabilitation after an Achilles rupture in order to reduce antagonist co-activation and enhance the plantarflexion torque. Our results further demonstrated that there are associations between the muscle activation of the medial gastrocnemius and the ankle joint in the concentric phase, and that soleus EMG activity is associated with high negative mechanical energy in the eccentric phase of the OLHR test. These correlations indicated the muscular contributions to the kinematic and kinetic characteristics during the OLHR test. [PERSON] et al. observed increased EMG activities in the medial gastrocnemius muscle during walking in patients with an Achilles rupture and declared these increased activities to be caused by tendon lengthening [30]. It is possible that the correlation found in the medial gastrocnemius muscle reflects its architecturally largest angulations of the fascicles, which favor force production [31], even though muscle fascicle shortening in the medial gastrocnemius muscle and Achilles tendon lengthening occur in the involved legs. The soleus EMG activity associated with negative mechanical energy during eccentric contractions implies a dependence of elastic energy storage on the soleus muscle that is accomplished through increases of muscle activity after an Achilles rupture.