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Effect of electrical stimulation superimposed with isokinetic contractions
G Poumarat1, P Squire, M Lawani
1Laboratory of Biomechanics and Instrumentation, Blaise Pascal University, Clermont-Ferrand, France.
The Journal of Sports Medicine and Physical Fitness
|September 1, 1992
Summary
Electrical stimulation (ES) during maximal voluntary contraction (MVC) did not enhance knee extension torque in non-athletes. Instead, ES significantly reduced peak torque, suggesting an inhibitory effect during isokinetic muscle action.
Area of Science:
- Biomechanics
- Exercise Physiology
- Neuromuscular Function
Background:
- Previous research examined electrical stimulation (ES) effects on maximal voluntary contraction (MVC) under isometric conditions.
- This study extends this research to isokinetic muscle actions, exploring neuromuscular responses during dynamic movements.
Purpose of the Study:
- To investigate the impact of superimposed electrical stimulation (ES) on isokinetic knee extension torque.
- To compare the effects of different stimulation frequencies (30 Hz and 80 Hz) on muscle torque production.
Main Methods:
- Eleven non-athletic males performed isokinetic knee extensions at 12°/s and 30°/s using a Cybex 340.
- Torque was measured during maximal voluntary contraction (MVC) alone and with superimposed ES (600 μs pulse width, 30 Hz or 80 Hz).
Main Results:
- Electrical stimulation (ES) did not alter the overall pattern of torque production during isokinetic knee extension.
- Peak torque was significantly lower with ES (both 30 Hz and 80 Hz) compared to MVC alone.
- This inhibitory effect was more pronounced at 80 Hz and observed in the mid-range of motion.
Conclusions:
- Superimposed ES appears to inhibit, rather than enhance, isokinetic knee extension torque in untrained individuals.
- Potential reasons include ES's inability to recruit additional motor units beyond MVC, current intensity limitations due to subject tolerance, and stimulation parameters.