Key result
The peak and normalized peak methods gave more similar torque/velocity relations than the angle-specific method during isovelocity knee flexion and extension.
Peak and normalized peak methods provide more consistent torque/velocity relations than angle-specific methods when assessing human knee muscle performance.
Supports preferring peak over angle-specific methods for consistent knee torque-velocity analysis; leaves open prospective validation in clinical populations.
Angle-specific (AS) torque/velocity data have been used to avoid angle related variation in peak torque capacity. However, series elastic structures cause the contractile velocity of active force-producing tissue to differ from external joint velocity except at peak torque. Alternatively, angle related variation may be removed by normalizing peak torque to the isometric maximum at that angular position. The AS, peak (P), and normalized peak (NP) methods were compared in isovelocity knee flexion and extension at velocities between 50 and 250 degrees s-1 for 8 male subjects. The P and NP methods gave more similar torque/velocity relations than the AS method. Further, very little variation in peak torque was attributed to differences in joint angle. Both the P and AS methods illustrate that relative quadriceps/hamstrings torque capability (flexor/extensor ratio) increases slightly with velocity. It is proposed that antagonist muscle torque capabilities should be compared at different angular positions to assess muscular imbalance.
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Caldwell et al. (1993) studied this question. Peak (P) and normalized peak (NP) methods vs. Angle-specific (AS) method was evaluated on Torque/velocity relations. The peak and normalized peak methods gave more similar torque/velocity relations than the angle-specific method during isovelocity knee flexion and extension.
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