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Are humans able to voluntarily elicit maximum muscle force?
J J Dowling1, E Konert, P Ljucovic
1Department of Kinesiology, McMaster University, Hamilton, Ont., Canada.
Neuroscience Letters
|September 26, 1994
Summary
Humans cannot voluntarily achieve maximum muscle activation. Even with maximal effort, the biceps brachii muscle can still produce additional force when electrically stimulated, suggesting untapped potential for muscle force generation.
Area of Science:
- Human physiology
- Neuromuscular function
- Biomechanics
Background:
- Previous research suggested maximal voluntary muscle activation is achievable.
- Electrical stimulation superimposed on voluntary contractions was used to assess this.
- The concept of voluntary activation limits remains a topic of investigation.
Purpose of the Study:
- To re-evaluate the extent of maximal voluntary muscle activation in humans.
- To investigate the voluntary activation of the human biceps brachii.
- To determine if subjects could voluntarily elicit maximal muscle force.
Main Methods:
- Employed the interpolated twitch technique.
- Utilized triggered averaging and doublet stimulation of the biceps brachii.
- Measured extra torque evoked by percutaneous stimulation during voluntary efforts.
Main Results:
- The decline in evoked extra torque was non-linear with increasing voluntary effort.
- No subject achieved full voluntary activation, as extra torque was always present.
- The extra torque decreased exponentially, indicating a potential for greater force.
Conclusions:
- Humans are likely incapable of achieving 100% voluntary muscle activation.
- The extrapolated maximum muscle force may significantly exceed voluntary capacity.
- Neuromuscular limitations, not just muscle force, may restrict maximal voluntary contraction.