# Characteristics of Changes in Contractile Properties of Muscle after Anaerobic Exercise
## 4 Discussion
\begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline
**Muscle** & **Parameter** & **Vmax** & **PPO** & **tPPO** & **AP** & **AC** & **FI** \\ \hline RF & d & Tc & \(-0.15\) & \(-0.31\) & \(-0.08\) & \(-0.31\) & \(-0.15\) & \(-0.39\) \\  & & Ts & \(-0.07\) & \(-0.07\) & \(-0.13\) & \(-0.11\) & \(-0.05\) & \(0.14\) \\  & & Tr & \(-0.18\) & \(0.03\) & \(-0.06\) & \(-0.18\) & \(-0.06\) & \(0.15\) \\  & & Dm & \(-0.29\) & \(-0.31\) & \(-0.02\) & \(-0.17\) & \(-0.02\) & \(-0.24\) \\  & & Td & \(-0.06\) & \(-0.12\) & \(0.33\) & \(-0.11\) & \(-0.24\) & \(-0.06\) \\ \hline SO & d & Tc & \(0.07\) & \(0.38\) & \(0.49\)\({}^{\star}\) & \(0.07\) & \(-0.02\) & \(0.46\) \\  & & Ts & \(-0.20\) & \(-0.40\) & \(-0.09\) & \(-0.12\) & \(0.12\) & \(-0.58\)\({}^{\star}\) \\  & & Tr & \(-0.37\) & \(-0.36\) & \(0.19\) & \(-0.26\) & \(-0.12\) & \(-0.25\) \\  & & Dm & \(0.12\) & \(0.24\) & \(0.41\) & \(0.06\) & \(0.09\) & \(0.18\) \\  & & Td & \(0.06\) & \(0.37\) & \(-0.06\) & \(-0.08\) & \(-0.26\) & \(0.48\) \\ \hline VL & d & Tc & \(0.24\) & \(0.06\) & \(0.12\) & \(0.00\) & \(-0.07\) & \(0.08\) \\  & & Ts & \(-0.14\) & \(-0.23\) & \(0.09\) & \(-0.29\) & \(-0.23\) & \(-0.38\) \\  & & Tr & \(-0.11\) & \(-0.33\) & \(0.01\) & \(-0.26\) & \(-0.22\) & \(-0.44\) \\  & & Dm & \(-0.03\) & \(-0.28\) & \(-0.11\) & \(0.08\) & \(0.13\) & \(-0.29\) \\  & & Td & \(0.04\) & \(-0.52\)\({}^{\star}\) & \(0.12\) & \(-0.15\) & \(-0.19\) & \(-0.43\) \\ \hline VM & d & Tc & \(-0.17\) & \(-0.29\) & \(0.00\) & \(-0.58\)\({}^{\star}\) & \(-0.54\)\({}^{\star}\) & \(-0.33\) \\  & & Ts & \(-0.13\) & \(-0.43\) & \(-0.15\) & \(0.06\) & \(-0.04\) & \(-0.09\) \\  & & Tr & \(-0.14\) & \(-0.29\) & \(-0.19\) & \(-0.12\) & \(-0.07\) & \(-0.08\) \\  & & Dm & \(0.02\) & \(-0.06\) & \(-0.01\) & \(0.19\) & \(0.21\) & \(-0.18\) \\  & & Td & \(-0.01\) & \(-0.07\) & \(0.16\) & \(-0.11\) & \(-0.06\) & \(-0.23\) \\ \hline \hline \end{tabular} d – index of difference; GT—glutueus maximus; VM—vastus medialis; VL—vastus lateralis; RF—rectus femoris; SO—soleus; GM—gastrocnemius medialis; GL—gastrocnemius lateralis; Tc—contraction time; Ts—sustain time; Tr—relaxation time; Dm—maximum radial muscle belly displacement; Td—delay time; \(V_{\text{max}}\)—maximal velocity; PPO—peak power output; \(t_{PPO}\)—time to peak power; AP—anerobic power; AC—anerobic capacity; FI—fatigue index; \({}^{\star}\)—statistical significance.  
\end{table} 
Table 4: _Cont._in anaerobic exercise. Thus, it can be concluded that anaerobic exercise has a significant effect on changes of skeletal muscle contractility parameters. Thus, it appears that TMG is an effective method for identifying differences in muscle response to training stimuli of anaerobic nature in particular. This makes TMG a useful tool to be used in monitoring the sports training process [10]. Based on monitoring muscle reactions to anaerobic exercise, coaches will be able to individually adjust the intensity of workouts and the length of rest periods between sets or exercises, thus optimizing athletic performance [2]. The obtained data can also be used to detect fatigue among subjects, minimizing the risk of muscle overload and, if necessary, implementing early preventive actions [6,18]. Assessing the effectiveness of muscle contractions will also allow for the identification of areas requiring further improvement. Therefore, TMG can be an effective tool for minimizing the risk of injuries [13] and for more accurately adjusting training to improve athletic performance [3]. Increased stiffness (Dm \(-\)6.33%) in the vastus lateralis muscle and delayed stimulus response in the vastus lateralis (Td 3.55%) and vastus medialis (Td 5.88%) muscles were observed. To our knowledge, only the study by [PERSON] et al. [24] characterized changes in TMG parameters after the Wingate test and exclusively in the vastus lateralis muscle. However, the results appeared to be similar to those obtained in our study. The authors showed a decrease in the Dm parameter (\(-\)38.5%) and an increase in the Td parameter (7.3%).