This study examines the effects of a 7 weeks sub-maximal training period of electrostimulation
on the maximal isometric, concentric, eccentric voluntary torque and muscle contractile
properties of the elbow flexor muscles of nine subjects. The daily program consisted
of five series of six 6-s isometric actions (60 to 70 % of maximal isometric voluntary
action) at an elbow angle of 90°. After training the maximal voluntary isometric flexion
torque increased significantly whereas the maximal voluntary isometric extension torque
decreased significantly. Increases in isometric flexion torque were linked to an increase
of the myoelectrical activity of the biceps brachii muscle. Under dynamic conditions
flexion torque was significantly increased throughout the whole spectrum of angular
velocities. These changes were accompanied by an increase in the myoelectrical activity
of the agonist muscle under eccentric conditions and at two fast concentric angular
velocities, without modifications of the myoelectrical activity of the antagonist
muscle. The analysis of the electrical and mechanical twitches indicated that modifications
of the muscle membrane electrical activity were also present at the muscle level.
These results indicate that torque gains were attributed to neural adaptations and/or
to a modification of the relative part of agonist and antagonist muscles in elbow
flexion torque production.
Electrostimulation training - co-activation - torque/angular velocity relationships
- torque/angular relationships - EMG - electrical and mechanical twitches
