## 4 Discussion
The greater reduction in knee extension and flexion strength in this study may be explained by the demands of football matches as players are required to perform multiple short high-intensity movements (e.g., kicking, acceleration, deceleration, sprints and rapid changes in direction) [47], which imposes elevated concentric and eccentric demands on the quadriceps and hamstrings muscles [30; 48; 49]. Previous studies have shown increases in some substances' concentration (e.g., creatine kinase, urea, uric acid) after a football match [22; 50; 51]. Although not measured in this study, the potential mechanisms explaining the strength reduction impairments may be related to disruptions within the muscular fibres [22]. Thus, myofibre disruptions have been suggested to be responsible for the decline in the force generation capacity after a football match [22; 52]. Moreover, our results also show that quadriceps and hamstring actions' \(\text{RFD}_{150}\) and \(\text{RFD}_{250}\) values decreased post-match (quadriceps: between \(-17.3\%\) and \(-30.3\%\) and hamstring: between \(-13.5\%\) and \(-17.0\%\)), and most of these values were recovered 48 h after the match. These findings partially agree with those reported by [PERSON] et al. [53], who found only a significant reduction in knee flexion \(\text{RFD}_{200}\) (\(-11\%\)) after a match in professional male football players. Conversely, our results show a greater impact on knee extensor \(\text{RFD}_{250}\) values that could be explained due to the existing relationship between the ability of the quadriceps to quickly produce a peak force and the deceleration [54] or kicking actions [55], which are numerous in a female football match. The difference between the findings could be explained by thigh muscle activity and sex differences in strength (greater strength in the quadriceps than in the hamstrings after menarche and greater muscle activity in the rectus femoris in female athletes than in male counterparts) [56; 57; 58]. Our data complete these findings as, for the first time, we have assessed the effect of a competitive football match on quadriceps and hamstring muscle isometric strength in amateur female football players. Regarding H:Q ratio measurements, we analysed this ratio for all strength variables before and after an official football match. This approach may provide a more accurate assessment of ACL and muscle injury risk in female football players, as the majority of these injuries occur during competitive matches [55; 59]. Our results show no post-match changes in the H:Q ratio for IPF; however the H:Q ratio for \(\text{RFD}_{150}\) and \(\text{RFD}_{250}\) assessments was increased post-match in the dominant leg by 22% and 38% (i.e., quadriceps muscles experienced higher reductions in RFD values than those of the hamstrings). Furthermore, H:Q ratios for RFD variables did not fully recover 48 h post-match, particularly in the dominant leg, unlike the isolated strength measurements of the quadriceps and hamstring muscles, which showed full recovery. This suggests that neuromuscular function, particularly the ability to generate force rapidly, remains impaired 48 h post-match due to the differing recovery rates of the quadriceps and hamstring muscles in returning to baseline levels. This H:Q ratio disruption could increase the risk of ACL and muscle injuries if players return to high-intensity activities before full neuromuscular recovery [31], although this is a hypothesis that requires further testing. The authors of this study speculate that these increases in \(\text{RFD}_{150}\) and \(\text{RFD}_{250}\) H:Q ratios may occur as the kicking and deceleration actions performed during the match involve the quadriceps more than the hamstring muscles in female football players [54; 55]. Additionally, the test position (\(30^{\circ}\) of knee flexion, with \(0^{\circ}\) representing full extension) places the hamstrings in a stretched state, providing a mechanical advantage to generate force compared to the quadriceps [60].