| Neuromuscular electrical stimulation (NMES) may be used to prevent
strength loss associated with post-surgical immobilization. Most studies
testing the effectiveness of NMES have trained the knee extensors.
The purpose of this investigation was to test the effectiveness of
NMES when training the elbow flexors. Twenty-four students were randomly
assigned to one of three groups: NMES training, isometric training
or control. Testing and training were completed using a Biodex™
dynamometer. After a standard warm-up, subjects were positioned on
the Biodex™ with left shoulder in anatomical neutral, elbow flexed
to 90o and forearm supinated. Subjects performed three
maximum isometric contractions of 5 seconds duration, with 1 min rest
between repetitions. Average peak torque during three repetitions
was calculated. Subjects trained on three days per week for four weeks.
Training included 15 maximum contractions of 15 seconds duration with
45 seconds recovery between repetitions. Russian current was delivered
by a Forte™ 400 Combo via electrodes placed over ends of biceps
brachii. A maximum tolerable ramped intensity was delivered with frequency
of 90 bps and duty cycle of 15:45. After training, subjects were post-tested
in a manner identical to pretest. Mean normalized strength data were
analyzed using a 3 (Group) x 2 (Test) ANOVA. The Group x Test interaction
was significant. Post-hoc analyses revealed that the voluntary training
group (normalized means of 0.49 to 0.71 for the pretest and post-test,
respectively) had a significantly greater increase than the other
two groups, which were not significantly different from each other.
The lack of significant strength gains with NMES was likely due to
low average training intensity, which was only 20.4% of MVIC. Based
on these results, NMES training may not be an effective alternative
to voluntary training in healthy subjects.
KEY
WORDS: Electrical stimulation, upper extremity, biceps, torque.
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