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Electromyographic activity and applied load during seated quadriceps exercises
J W Matheson1, T W Kernozek, D C Fater
1Program in Physical Therapy, Health Science Center, University of Wisconsin-La Crosse, La Crosse, WI 54601, USA. montana@fflax.net
Medicine and Science in Sports and Exercise
|October 3, 2001
Summary
This study compared quadriceps muscle activity during seated exercises using different resistance types. Inertial resistance showed greater muscle activation in the eccentric phase, suggesting varied exercise appropriateness for rehabilitation goals.
Area of Science:
- Biomechanics
- Exercise Physiology
- Rehabilitation Science
Background:
- Quadriceps muscle strengthening is crucial for lower limb function and rehabilitation.
- Understanding the electromyographic (EMG) activity and applied load of various seated exercises is essential for program design.
- Different resistance modalities may elicit varying muscle responses.
Purpose of the Study:
- To quantify and compare mean quadriceps muscle activity and applied load for eight seated exercises.
- To evaluate four distinct resistance types: ankle weight, elastic tubing, isokinetic dynamometer, and inertial resistance trainer.
- To analyze muscle activation patterns across concentric and eccentric phases.
Main Methods:
- Surface electromyography (EMG) measured rectus femoris (RF), vastus lateralis (VL), and vastus medialis oblique (VMO) activity in 52 university students.
- Resistance devices included ankle weights, Thera-Band tubing, Cybex dynamometer, and an Inertial Exercise Trainer (IET).
- Electrogoniometry and load cells quantified range of motion, velocity, phase, and applied loads; EMG was normalized to maximum voluntary isometric contraction.
Main Results:
- Significant within-subject effects of muscle and exercise were found for both concentric and eccentric muscle activity (P < 0.05).
- The interaction of mean EMG amplitude across exercises was significant for the concentric phase of knee extension (P = 0.001).
- Inertial resistance resulted in greater eccentric phase muscle activity, and VMO/VL ratios were lower with free weights and elastic tubing during concentric phases.
Conclusions:
- Clinicians should consider biomechanical and resistance data when designing quadriceps strengthening programs.
- Specific seated quadriceps exercises may be more suitable for particular rehabilitation objectives.
- The choice of resistance type significantly influences quadriceps muscle activation patterns.