Effect of resisted knee flexion on knee extension torque

Area of Science:

• Biomechanics
• Exercise Physiology

Background:

• The principle of reversal of antagonists suggests that maximal contraction of an agonist muscle is enhanced by prior contraction of its antagonist.
• This phenomenon is often considered in athletic training and performance, but its applicability in isokinetic testing requires empirical validation.

Purpose of the Study:

• To investigate whether resisted knee flexion influences subsequent peak knee extension torque.
• To determine if the principle of reversal of antagonists applies to isokinetic testing of knee extensors in healthy individuals.

Main Methods:

• A crossover design was employed with 18 healthy adults performing isokinetic knee extension at 60 and 120 degrees/sec.
• Peak knee extension torque was measured during reciprocal movements with either passive or maximal voluntary resisted knee flexion.

Main Results:

• No statistically significant difference was found in peak knee extension torque between the passive and resisted knee flexion conditions.
• The results were consistent across both tested velocities (60 and 120 degrees/sec).

Conclusions:

• Resisted knee flexion does not augment peak knee extension torque under the tested isokinetic conditions.
• The principle of reversal of antagonists was not supported, suggesting it may be irrelevant for isokinetic testing and training in neurologically healthy individuals.