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Electrically elicited quadriceps muscle torque: Comparison at three knee angles
Wayne Scott1, Cheryl Adams1, Jason Fisher1
1School of Physical Therapy, Husson University, Bangor, ME, USA.
Physiotherapy Theory and Practice
|July 12, 2019
Summary
This study found that 60° knee flexion produced the greatest electrically elicited quadriceps torque and the highest percentage of maximal voluntary isometric torque. Optimal knee angle is crucial for electrical muscle stimulation effectiveness.
Area of Science:
- Biomechanics
- Neuromuscular Physiology
- Rehabilitation Engineering
Background:
- The influence of knee joint angle on electrically induced quadriceps muscle torque remains underexplored.
- Understanding optimal joint angles is critical for maximizing torque output during electrical stimulation protocols.
Purpose of the Study:
- To determine the knee angle that yields the greatest knee extensor maximal voluntary isometric torque (KEMVIT).
- To identify the knee angle that maximizes electrically elicited quadriceps torque.
- To ascertain the knee angle that results in the highest percentage of KEMVIT achieved through electrical stimulation.
Main Methods:
- Eighteen participants were tested using a force dynamometer at knee flexion angles of 30°, 60°, and 90°.
- Participants performed maximal voluntary isometric contractions (KEMVITs) followed by electrically elicited contractions to maximum tolerance at each angle.
Main Results:
- KEMVIT was significantly greater at 60° and 90° compared to 30° (p < 0.001).
- Maximal tolerated electrically elicited torque was significantly higher at 60° compared to 30° (p < 0.001) and 90° (p = 0.018).
- The percentage of KEMVIT achieved via electrical stimulation was significantly higher at 60° compared to 30° (p = 0.001) and 90° (p < 0.001).
Conclusions:
- Knee extensor torque, both voluntary and electrically elicited, is angle-dependent.
- A knee flexion angle of 60° optimizes electrically elicited quadriceps torque production and its relation to maximal voluntary effort.
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