Comparison of Quadriceps and Hamstring Torque Values during lsokinetic Exercise

Area of Science:

• Biomechanics
• Exercise Physiology
• Musculoskeletal Research

Background:

• Understanding maximal voluntary muscular torque is crucial for assessing muscle function and performance.
• Isokinetic exercise provides a standardized method for evaluating muscle strength across different speeds.

Purpose of the Study:

• To investigate maximal voluntary muscular torque output of quadriceps and hamstrings during isokinetic exercise.
• To analyze the influence of exercise speed on torque production and inter-muscle group ratios.

Main Methods:

• Tested 100 healthy adults (50 male, 50 female, aged 25-34) on the Cybex II isokinetic dynamometer.
• Measured maximal voluntary torque of quadriceps and hamstrings at knee angular velocities of 60, 180, and 300 degrees per second.
• Calculated means, standard deviations, ranges, and performed analysis of variance on torque data.

Main Results:

• Torque output decreased significantly as exercise speed increased for both muscle groups.
• Quadriceps torque was significantly greater than hamstring torque across all tested speeds.
• The hamstring-to-quadriceps torque ratio increased significantly with increasing exercise speed.
• Significant differences in dominant vs. nondominant knee torque were observed in males but not females.
• Nondominant to dominant knee torque ratios were consistently high (≥97%), with minimal absolute differences (≤12 foot-pounds).

Conclusions:

• Exercise speed is a critical factor influencing maximal voluntary muscular torque and muscle group strength ratios.
• While quadriceps generally produce greater torque, the relative contribution of hamstrings increases at higher speeds.
• Leg dominance has a minor impact on knee extensor and flexor torque symmetry in healthy young adults.