# Morphological and Mechanical Symmetry of the Quadriceps and Hamstrings in Athletes
## 3 Results  
Descriptive characteristics such as sex, experience, age, height, body mass, and body mass index are summarized in Table 1.  
Furthermore, Table 2 shows the comparisons between the DO and ND of team sports athletes for all variables (\(p\) > 0.05). Furthermore, ES between the lower limbs presented values between trivial and moderate for all evaluated variables (Table 2). The multicollinearity results demonstrated that none of the independent variables of the quadriceps (VIF \(\leq\) 1.255) and hamstrings (VIF \(\leq\) 1.153) were excluded from the backward multiple linear regression models. As shown in Table 3, 60.8% of maximal concentric knee extensor of DO at 60\({}^{\circ}\)/s can be explained together by positive relation with quadriceps CSA and negative relation with quadriceps EI [\(F\)(2, 13) = 10.071; \(p\) = 0.002], whereas 78.7% of maximal concentric knee extensor of DO limb at 300\({}^{\circ}\)/s can be explained together by positive relation with quadriceps CSA and negative relation with quadriceps EI [\(F\)(2, 13) = 24.048; \(p\) < 0.001]. Similarly, 61.0% of maximal concentric knee extensor of ND limb at 60\({}^{\circ}\)/s can be explained together by positive relation with quadriceps CSA and negative relation with quadriceps EI [\(F\)(2, 13) = 10.148; \(p\) = 0.002], whereas 74.9% of maximal concentric knee extensor of ND limb at 300\({}^{\circ}\)/s can be explained together by positive relation with quadriceps CSA and negative relation with quadriceps EI [\(F\)(2, 13) = 19.374; \(p\) < 0.001]; Figure 2.  
Moreover, 75.2% of maximal concentric knee flexor of DO at 60\({}^{\circ}\)/s can be explained together by positive relation with hamstrings CSA and EI [\(F\)(2, 13) = 19.684; \(p\) < 0.001], whereas 70.4% of maximal concentric knee flexor of DO limb at 300\({}^{\circ}\)/s can be explained together by positive relation with hamstrings CSA and EI [\(F\)(2, 13) = 15.493; \(p\) < 0.001]. Likewise, 70.8% of maximal concentric knee flexor of ND limb at 60\({}^{\circ}\)/s can be explained together by positive relation with hamstrings CSA and EI [\(F\)(2, 13) = 15.763; \(p\) < 0.001], whereas 77.2% of maximal concentric knee flexor of ND limb at 300\({}^{\circ}\)/s can be explained together by positive relation with hamstrings CSA and EI [\(F\)(2, 13) = 16.876; \(p\) < 0.001]; Figure 3. \begin{table}
\begin{tabular}{c c c c c c c} \hline
**Variables** & **Dominant** & **Non-Dominant** & **AI (\%)** & \(p\)**-Value** & **t-Value** & **ES** \\ \hline CSA-Q (cm\({}^{2}\)) & 101.4 \(\pm\) 32.9 & 100.7 \(\pm\) 28.7 & 0.65 & 0.779 & 0.285 & 0.071 \\ EI-Q (A.U.) & 38.4 \(\pm\) 6.2 & 37.1 \(\pm\) 5.2 & 3.18 & 0.075 & 1.910 & 0.478 \\ CSA-H (cm\({}^{2}\)) & 38.8 \(\pm\) 10.4 & 39.0 \(\pm\) 8.6 & \(-\)0.62 & 0.794 & \(-\)0.266 & 0.067 \\ EI-H (A.U.) & 47.0 \(\pm\) 4.8 & 45.0 \(\pm\) 6.0 & 4.34 & 0.118 & 1.660 & 0.415 \\ T60-Q (N\(\cdot\)m) & 213.6 \(\pm\) 52.3 & 218.5 \(\pm\) 67.0 & \(-\)2.26 & 0.530 & \(-\)0.643 & 0.161 \\ T300-Q (N\(\cdot\)m) & 134.1 \(\pm\) 43.0 & 133.4 \(\pm\) 43.1 & 0.50 & 0.826 & 0.224 & 0.056 \\ T60-H (N\(\cdot\)m) & 111.1 \(\pm\) 32.2 & 108.8 \(\pm\) 34.6 & 2.08 & 0.378 & 0.909 & 0.227 \\ T300-H (N\(\cdot\)m) & 94.8 \(\pm\) 26.4 & 89.7 \(\pm\) 26.3 & 5.37 & 0.059 & 2.042 & 0.510 \\ \hline \end{tabular}  
* AI: asymmetry index; ES: effect size; CSA-Q: cross sectional area of quadriceps; EI-Q: echo intensity of quadriceps; CSA-H: cross sectional area of hamstrings; EI-H: echo intensity of hamstrings; T60-Q: quadriceps torque at 60\({}^{\circ}\)/s; T300-Q: quadriceps torque at 300\({}^{\circ}\)/s; T60-H: hamstring torque at 60\({}^{\circ}\)/s; T300-H: hamstring torque at 300\({}^{\circ}\)/s.  
\end{table} 
Table 2: Between-sides comparison for quadriceps and hamstrings muscle morphology and maximal knee extensor and flexor torque (dependent sample \(t\)-test).