Isokinetic Muscle Torque Of The Knee At Different Velocities

PURPOSE: This study aimed to examine if there was a difference in the quadricep-to-hamstring (Q:H) ratio during isokinetic knee flexion and extension in the planting leg of female soccer players. METHODS: 16 volunteer female athletes aged 18-21 from Methodist University (Height: 1.62 ± 0.007 m; Body mass: 64.23 ± 11.5 kg, 16 R dominant & no L dominant) participated in the study. Participants performed voluntary isokinetic quadriceps and hamstring contractions at 60°/s, 180°/s, and 300°/s, respectively, using a Biodex. The knee extension peak torque divided by the knee flexion peak torque was recorded to represent the Q:H ratio. The angle at peak torque was also recorded. A 1-way analysis of variance (ANOVA) was used to determine the differences in the Q:H ratio and the angle at peak torque among the different isokinetic velocities. RESULTS: A significant difference in the Q:H ratio was found between the isokinetic velocities (F (2,45) = 3.13, p = .05). Follow-up tests found a significantly higher Q:H ratio at 300°/s (M = 1.34, sd = 0.36) compared to the 60°/s (M = 1.66, sd = 0.39) and the 180°/s (M = 1.57, sd = 0.37). A significant difference was also found in the flexion angle at peak torque between the isokinetic velocities (F (2,45) = 8.29, p = .0008). Follow-up tests revealed a significantly higher flexion angle at peak torque at 300°/s (M = 78.88, sd = 33.58°.) compared to the 60°/s (M = 50.19, sd = 11.35°) and the 180°/s (M = 48.0, sd = 21.49°). No significant difference was found in the extension angle at peak torque. CONCLUSION: Increases in joint velocity angles demonstrated increases in the hamstring eccentric strength as the Q:H ratio begins to be closer to 1.3:1 as compared to the current gold standard of 2:1 ratio seen at lower velocities. It is theorized that this increase in the ratio is due to the hamstrings acting as a dynamic stabilizer of the knee joint. If this ratio does not approach 1.3:1, it may be an indicator that predisposes athletes to injury.