Inertial effects on moment development during isokinetic concentric knee extension testing

Area of Science:

• Biomechanics
• Kinesiology
• Sports Science

Background:

• Torque acceleration energy, a measure of muscle explosive power, is debated.
• Moments from acceleration in early isokinetic movements are often overlooked.
• Understanding inertial effects is key to accurate isokinetic testing.

Purpose of the Study:

• To evaluate inertial effects on moment measurements during the initial acceleration phase of concentric isokinetic knee extension.
• To determine the impact of inertial effects on torque acceleration energy calculations.
• To assess the validity of isokinetic measurements with and without inertial correction.

Main Methods:

• A two-group pre-test post-test design was employed.
• Isokinetic knee extension was tested on Biodex and Lido dynamometers at various angular velocities.
• Joint moment calculations incorporated moments from angular acceleration and lever arm effects.

Main Results:

• Torque acceleration energy was significantly higher with inertial correction compared to uncorrected measures.
• This difference was observed at moderate (165-180 deg/s) and high (300 deg/s) velocities.
• Inertial effects demonstrably influenced moment measurements on both dynamometers.

Conclusions:

• At high angular velocities, inertial correction is essential for valid moment measurements and conclusions regarding muscle and joint function.
• For measuring moment development in the initial 0.125 seconds, slower velocities minimize inertial effects.
• Accurate isokinetic assessments require careful consideration of inertial effects, particularly at higher speeds.