Comparative analysis of isokinetic ratios between hamstrings and quadriceps in wrestlers: Resting state versus...

Wrestling demands high-intensity competition, and tournament structures often require athletes to compete in multiple matches in a single day. This results in accumulated neuromuscular fatigue that may disrupt the balance between hamstring and quadriceps strength, potentially increasing the risk of knee injuries. Therefore, this study aimed to determine whether the conventional hamstring-quadriceps ratio (H: QConv) and functional hamstring-quadriceps ratio (H: QFunc) are more indicative in resting and post-fatigue states, examine the H: QConv and H: QFunc isokinetic strength ratios, and analyze the contributions of hamstring and quadriceps strength changes to these ratios.

The study involved 16 wrestlers who achieved national championship rankings. Their average age was 15.0 ± 1.2 years, with an average height of 171.6 ± 8.6 cm and weight of 65.1 ± 16.6 kg. Their BMI was 21.8 ± 4.0 kg/m², and they had an average of 4.3 ± 1.0 years of training experience. The athletes participated in isokinetic assessments both at rest and after fatigue. The concentric and eccentric strengths of the hamstrings and concentric strength of the quadriceps were measured at angular velocities of 60°/s and 180°/s, respectively.

Two-factor repeated-measures ANOVA revealed a highly significant main effect of time on quadriceps concentric (QCON)(F(1,15)=106.789, p < .001, η²ₚ = .877), and angular velocity and interaction were not significant. For HCON, there was no time effect, but the velocity effect was significant (60°/s > 180°/s; F(1,15)=31.771, p < .001, η²ₚ = .679). For hamstring eccentric (HECC), the time and interaction effects were insignificant, and the velocity remained at the threshold (F(1,15)=3.654, p = .075). The H: QConv ratio generally increased after fatigue (F = 17.492, p = .001), and there was a level difference between velocities (F = 9.147, p = .009), but the interaction was insignificant. Both time (F = 59.489, p < .001) and velocity (F = 6.716, p = .020) were significant for the H: QFunc ratio, as was the time × velocity interaction (F = 4.708, p = .046); the increase was particularly reliable at 60°/s (Δ=+0.131, 95% CI [0.044, 0.218], p = .006). In the component decompositions, the increase in the time effect was shared similarly by the hamstrings and quadriceps, whereas the hamstrings' contribution significantly drove the angular velocity difference.

Fatigue significantly reduced the concentric torque of the quadriceps, whereas the concentric/eccentric outputs of the hamstrings were relatively preserved; consequently, the H: Q balance increased, particularly at 60°/s. The time effect was strong for H: QFunc, and a time×velocity interaction was present: the increase was reliable at 60°/s but not statistically confirmed at 180°/s. Component decomposition showed that the time-related change was shared to a similar extent by both muscles, whereas the hamstring contribution predominantly explained the angular velocity difference.