Article

OBJECTIVE: To determine the morphologic and histologic effects of electrical
stimulation (ES) used to prevent muscle atrophy, and to investigate the effects
of ES at different stimulation frequencies in preventing atrophy in different
muscle fiber types.
DESIGN: Rats in the hindlimb suspended (HS) plus ES group
were subjected to 20- and 30-Hz stimulation (ES1, ES2) every other day for 2 wks.
RESULTS: In soleus, the muscle weight, muscle fiber cross-sectional area, and the
number of type I muscle fibers were significantly decreased in the HS and HS +
ES2 groups, whereas they were maintained in the HS + ES1 group. This indicated
that ES at 20 Hz could suppress muscle atrophy and retain muscle fiber type
proportions, based on histologic properties. In extensor digitorum longus, the
muscle weight, muscle fiber cross-sectional area, and the number of type II
muscle fibers were significantly decreased in the HS group, whereas they were
maintained in the HS + ES groups. This indicated that ES at either 20 Hz or 30 Hz
could suppress muscle atrophy, and retain muscle fiber type proportions, based on
histologic properties. ES at 30 Hz also had positive effects in maintaining the
extensor digitorum longus muscle. CONCLUSIONS: These results suggest that short
periods of low-intensity, low-stimulation frequency (20 Hz) ES of muscle during
periods of inactivity could maintain changes in both morphologic and histologic
properties of the slow-twitch muscle fibers (soleus). Short periods of
low-intensity, high-stimulation frequency (30 Hz) ES of muscle during periods of
inactivity could maintain changes in both morphologic and histologic properties
of the fast-twitch muscle fibers (extensor digitorum longus).

Langue : ANGLAIS