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Interplay between body stabilisation and quadriceps muscle activation capacity
Theodoros M Bampouras1, Neil D Reeves2, Vasilios Baltzopoulos3
1Department of Medical and Sport Sciences, University of Cumbria, Lancaster, UK; School of Healthcare Science, Manchester Metropolitan University, Manchester, UK.
Summary
Stabilizing the leg and pelvis is crucial for maximizing quadriceps muscle activation and torque during maximal isometric voluntary contractions (MVC). Proper stabilization ensures accurate functional assessments using dynamometry.
Area of Science:
- Biomechanics
- Human Physiology
- Sports Science
Background:
- Maximal isometric voluntary contraction (MVC) is a key measure in assessing muscle strength.
- The influence of body stabilization on quadriceps MVC torque and muscle activation is not fully elucidated.
- Understanding factors affecting MVC is vital for accurate functional assessments.
Purpose of the Study:
- To differentiate the impact of stabilization versus muscle activation on quadriceps MVC torque.
- To investigate how different stabilization techniques affect knee extensor strength.
- To inform best practices for dynamometry-based functional assessments.
Main Methods:
- Nine subjects performed four MVC conditions: Typical MVC, Handgrip MVC, Isolated knee extension MVC, and Unrestrained MVC.
- Torque and muscle activation were measured using repeated measures ANOVA and dependent t-tests.
- Electromyography (EMG) of eleven remote muscles was analyzed using Friedman's and Wilcoxon tests.
Main Results:
- Typical MVC and Handgrip MVC yielded significantly higher torque than Isolated knee extension MVC and Unrestrained MVC.
- Muscle activation was highest in Typical MVC and Handgrip MVC conditions.
- EMG differences were observed in specific remote muscles, with Isolated knee extension MVC showing consistently lower activation.
Conclusions:
- Segmental stabilization is paramount for achieving maximal quadriceps muscle activation and torque.
- Inadequate stabilization, as seen in the Unrestrained MVC, significantly reduces force output.
- Dynamometry protocols for knee joint function should prioritize precise stabilization techniques.