Abstract
The basic stretch reflex responses evoked by the mechanical stimuli were investigated
among different athletic groups. The tests were performed by a special ankle ergometer,
which created dorsiflexion velocities from 25 deg × s-1 to 115 deg × s-1 around the ankle joint. The EMG activity of soleus (SO), gastrocnemius (GA) and tibialis
anterior (TA) muscles was recorded with surface electrodes. In all subjects higher
angular velocities caused higher stretch reflex responses. The endurance-trained athletes
were more sensitive to the used stimuli than the power-trained athletes, because of
their shorter latency times (43±7 ms vs 45±7 ms, p<0.001 for the SO muscle and 40±8
ms vs 43±6 ms, p<0.001 for the GA muscle), longer duration of action potentials and
shorter recovery times of the monosynaptic reflex. Thus, the neural control of reflex
movements in skeletal muscles was dependent on the training background of the subjects.
Additionally, the findings may be explained by differences in the motor unit composition
as well as by possible differences in the muscle spindle density of the two subject
groups.
Key words
Stretch reflex - EMG - stimulation - training
