Abstract
The present study aimed to examine the effect of short-term training utilizing voluntary
co-contraction with maximal efforts. 23 healthy young men (training group: TG, n=13;
control group: CG, n=10) participated in this study. TG conducted a 4-week training
program (3 days/week), which consisted of 4s simultaneous maximal voluntary contractions
of elbow flexors and extensors at 90°of the elbow joint, followed by 4s muscle relaxation
(10 repetitions/set, 5 sets/day). Before and after the intervention, maximal voluntary
isometric and isokinetic torques and the muscle thicknesses of the elbow flexors and
extensors were determined. The electromyograms (EMGs) of the 2 muscle groups during
isometric maximal voluntary contraction (MVC) were also recorded. After the intervention,
CG did not show any significant changes in all measured variables. In TG, significant
increases were found in the agonist EMG activities during MVC, and maximal isometric
and isokinetic torques of the elbow flexors and extensors, without significant changes
in the muscle thicknesses and involuntary coactivation levels during MVC. The current
results indicate that the training mode with maximal voluntary co-contraction is effective
for improving the force-generating capabilities of the exercising muscles, without
any increases in the level of involuntary coactivation during MVC.
Key words
static and dynamic torques - antagonist muscle - coactivation - EMG-torque relationship