The effect of high and low contraction velocity training on cross education and muscle hypertrophy
Date
2001
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Degree Level
Masters
Abstract
The purpose of this study was twofold: 1. To determine the effect of isokinetic
eccentric training at high and low contraction velocity on cross education, and 2. To
determine the effect of isokinetic eccentric and concentric training at high and low
contraction velocity on muscle hypertrophy. Cross Education is defined as an increase in
strength of the untrained (contralateral) limb after a period of unilateral (single limb)
resistance training. The effect is especially evident after eccentric training. Muscle
hypertrophy is the increase in muscle size. Twenty-six untrained volunteer subjects (11
males and 15 females, age 18-36) were randomized into either a fast velocity (180°/s)
training group (FAST) or a slow velocity (30°/s) training group (SLOW), where they
would complete two eight-week phases of unilateral isokinetic resistance training of the
elbow flexors muscle group. Each training phase was separated by a five-week wash out
phase. Phase I included only eccentric training of either the right or left arm
(randomized), and Phase II included only concentric isokinetic training of the opposite
arm. Ten additional subjects (2 males and 8 females) served as non-training controls
(CTR). Pre and post elbow flexors peak torque in both arms at eccentric fast (180°/s) and
slow (30°/s), and concentric fast (180°/s) and slow (30°/s) velocity was measured on a
Biodex isokinetic dynamometer. Pre and post elbow flexors muscle thickness in both
arms was measured by B-mode muscle ultrasound. Electromyography (EMG)
measurements were taken from the elbow flexors of both arms during a single training
session in both phases of the experiment. At the completion of eccentric training at the
end of Phase I, cross education could be analyzed. Fast velocity eccentric training
resulted in significant cross education (13%; p< .05), which was specific to the training velocity (180°/s). Slow velocity eccentric training failed to result in any significant
strength changes in the untrained arm. After Phase I, there were no significant changes in
muscle thickness for the untrained arm in any group, and the average EMG activity in the
non-training arm of the training groups was negligible (1.6% of EMG during maximal
isometric contractions). At the end of Phase II, six separate groups of arms were
compared: 1. Eccentric fast trained (ECCFAST), 2. Eccentric slow trained (ECCSLOW),
3. Concentric fast trained (CONFAST), 4. Concentric slow trained (CONSLOW), 5.
Eccentric control arm (CTR), and 6. Concentric control arm (CTR). Overall the
eccentrically trained arms resulted in greater changes in muscle thickness than the
concentrically trained arms.
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Degree
Master of Science (M.Sc.)
Department
College of Kinesiology
Program
College of Kinesiology