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Electromyostimulation training effects on neural drive and muscle architecture
Julien Gondin1, Marie Guette, Yves Ballay
1INSERM/ERM 207 Laboratory, Faculty of Sport Sciences, University of Burgundy, Dijon, France. julien.gondin@u-bourgogne.fr
Medicine and Science in Sports and Exercise
|August 25, 2005
Summary
Electromyostimulation (EMS) training enhances knee extensor strength through both muscle growth and improved neural activation. These adaptations primarily benefit the vastii muscles after 8 weeks.
Area of Science:
- Sports Science
- Muscle Physiology
- Rehabilitation Medicine
Background:
- Neuromuscular electrical stimulation (NMES) is a therapeutic modality used to induce muscle contractions.
- Understanding the specific adaptations to NMES is crucial for optimizing training protocols.
Purpose of the Study:
- To investigate the muscular and neural adaptations in knee extensor muscles following 4 and 8 weeks of NMES training.
- To differentiate between adaptations in monoarticular and biarticular muscles.
Main Methods:
- Twenty healthy males participated, divided into an NMES group (N=12) and a control group (N=8).
- An 8-week isometric NMES protocol involving 32 sessions was administered.
- Assessments included maximal voluntary contractions (MVC), EMG activity, muscle cross-sectional area (ACSA), and pennation angle via ultrasonography.
Main Results:
- After 8 weeks, significant increases were observed in knee extensor MVC (27%), muscle activation (6%), quadriceps ACSA (6%), and vastus lateralis (VL) pennation angle (14%).
- Normalized EMG activity increased significantly in VL (69%) and vastus medialis (VM) (39%), but not rectus femoris (RF).
- ACSA of VL, VM, and vastus intermedius increased (5-8%) at 8 weeks, but not at 4 weeks, with no changes in RF.
Conclusions:
- Voluntary torque gains following NMES training result from combined muscular and neural adaptations.
- These adaptations predominantly affect the monoarticular vastii muscles (VL, VM, vastus intermedius).