# Influence of Knee Angle on Hametring/Quadriceps Strength Ratio in Male Soccer Players
## 4 Discussion  
The relationship between isokinetic concentric strength at 60\({}^{\circ}\)/s and 180\({}^{\circ}\)/s of the hamstring and quadriceps musculature (ratio) at different knee flexion angles was studied. The results obtained in our study indicate that at low angular velocities in isokinetic tests (60\({}^{\circ}\)/s), in addition to the conventional H/Q ratio, the H/Q ratios at 15\({}^{\circ}\) and 30\({}^{\circ}\) knee flexion should be considered since they are unique and provide more information on the athlete's muscular state. Our results align well with those obtained by [PERSON] et al. [34]. Although the hip flexion was slightly higher (120\({}^{\circ}\)) and the measured velocities were different (15\({}^{\circ}\)/s and 90\({}^{\circ}\)/s) than in [PERSON] et al. 's [34] study, the relationships found in terms of the calculated ratios were similar to ours. The H/Q ratios at 15\({}^{\circ}\)/s decreased as the knee flexed. At 15\({}^{\circ}\) and 30\({}^{\circ}\) of knee flexion, higher H/Q ratios were observed (2.00 (0.37) and 1.43 (0.33)) than the ratios obtained with higher knee flexion angles (0.89 (0.19) and 0.50 (0.11)) and comparatively with the conventional ratio obtained (0.70 (0.13)). The same occurred at 90\({}^{\circ}\)/s, with 15\({}^{\circ}\) and 30\({}^{\circ}\) of knee flexion; higher H/Q ratios were observed (1.24 (0.32) and 0.90 (0.20)) than the ratios obtained with greater knee flexion angles (0.75 (0.18) and 0.65 (0.13)) and the conventional ratio (0.66 (0.11)). The results may improve for the hamstring injuries risk assessment because evaluating H/Q ratios at 15\({}^{\circ}\) and 30\({}^{\circ}\) of knee flexion, where hamstring injuries are more likely to occur, provides a more accurate assessment of muscle imbalances than the conventional ratio. Some authors claim that strength ratios measured with a dynamometer can predict the risk of hamstring injury, and others claim the opposite [26]. In the systematic review by [PERSON] et al. [35], the mean values of the conventional H/Q ratios of soccer players at different angular velocities measured with the participant seated (hip with 90\({}^{\circ}\) of flexion) were established. In the conventional H/Q ratio at 60\({}^{\circ}\)/s, the values were 0.65 \(\pm\) 0.12 and at 180\({}^{\circ}\)/s 0.67 (0.17), results similar to those obtained in our study (0.59 (0.08) and 0.67 (0.09), respectively). The cut-off point of the conventional H/Q ratio (below these values, we can consider the risk of muscle rupture) is 0.47 [26]. In contrast to the above, [PERSON] et al. [27] mentioned \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Variable** &
\begin{tabular}{c} **Median** \\ **(Q1–Q3)2**  & **P-Value** \\ \hline H/Q ratio at & 0.52 & & & 60\({}^{\circ}\)-15\({}^{\circ}\) & 0.006 *  & 0.64 \\
60\({}^{\circ}\) knee flexion & (0.41–0.64) & & & 60\({}^{\circ}\)-30\({}^{\circ}\) & 0.013 *  & 0.68 \\  & & & 60\({}^{\circ}\)-45\({}^{\circ}\) & 1.0 & - \\  & & & 60\({}^{\circ}\)-75\({}^{\circ}\) & 1.0 & - \\  & & & 60\({}^{\circ}\)-conventional & 0.032 *  & 0.56 \\ \hline  & & & 75\({}^{\circ}\)-15\({}^{\circ}\) & 0.026 *  & 0.59 \\  & & 75\({}^{\circ}\)-30\({}^{\circ}\) & 0.044 *  & 0.61 \\  & & 75\({}^{\circ}\)-45\({}^{\circ}\) & 1.0 & - \\  & & & 75\({}^{\circ}\)-60\({}^{\circ}\) & 1.0 & - \\  & & & 75\({}^{\circ}\)-conventional & 0.130 & - \\ \hline  & & & \multicolumn{1}{c}{} & Conventional-15\({}^{\circ}\) & 0.04 *  & 0.58 \\  & & & Conventional-30\({}^{\circ}\) & 1.0 & - \\  & & Conventional-45\({}^{\circ}\) & \textless{}0.001 *  & 0.8 \\  & & Conventional-60\({}^{\circ}\) & 0.032 *  & 0.56 \\  & & Conventional-75\({}^{\circ}\) & 0.130 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 2: _Cont._that these data should not be taken as the only reference for predicting hamstring injury since, in their study, only 2.7% of the injured players were below these values. In relation to the above, [PERSON] et al.