Relationship between maximal strength and hamstring-to-quadriceps ratios in balanced and unbalanced legs in futsal athletes

Hamstring-to-quadriceps (H:Q) strength ratio has been used to estimate injury risk and readiness to return to sport. Previous studies have investigated if H:Q ratios are determined by the weakness of knee flexors (KF) or strength of knee extensors (KE) in soccer players. However, the results on H:Q ratio determinants are divergent. Moreover, studies with this proposal involving futsal athletes were not found. The present study aimed to verify: (a) the global correlation between KF (KFPT) and KE peak torque (KEPT) with conventional and functional H:Q ratios, (b) the correlation according to balanced and unbalanced H:Q ratio conditions and (c) the KFPT and KEPT between balanced and unbalanced legs. Male professional futsal players (46 athletes, 24.65 ± 6.78 years) participated in this study. Using a global analysis (balanced + unbalanced legs), H:Q ratios were significantly related to concentric KFPT (r = 0.36–0.46), eccentric KFPT (r = 0.37–0.63) and concentric KEPT (r = − 0.31 to − 0.30). Balanced legs had a significant negative relationship between KEPT and H:Q ratios (r = − 0.51 to − 0.35). In contrast, unbalanced legs presented significant positive associations between H:Q ratios with concentric KFPT (r = 0.39–0.41) and eccentric KFPT (r = 0.52–0.65) but not KEPT. Finally, unbalanced legs showed lower KFPT and higher KEPT than balanced legs. In the global analysis, KFPT and KEPT were correlated with H:Q ratios. However, using specific analyses, KEPT was negatively related to H:Q ratios in balanced legs but not unbalanced legs. In unbalanced legs, concentric KFPT and eccentric KFPT presented significant positive associations with H:Q ratios.