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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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MUSCLE ACTIVATION DURING LOW-INTENSITY MUSCLE CONTRACTIONS WITH VARYING LEVELS OF EXTERNAL LIMB COMPRESSION |
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Tomohiro Yasuda1,3, William F. Brechue2, Taku Fujita1, Yoshiaki Sato3 and Takashi Abe4 |
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1Department of Exercise and Sport Science, Graduate School of Science, Tokyo Metropolitan University, Tokyo, Japan 2Center for Physical Development Excellence, Department of Physical Education, United States Military Academy, West Point, New York, United States, 3Department of Ischemic Circulatory Physiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan, 4Institute of Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan |
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© Journal of Sports Science and Medicine (2008) 7, 467 - 474 Search Google Scholar for Citing Articles |
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| ABSTRACT | |||
| The purpose was to investigate muscle activation during low- intensity
muscle contractions with various levels of external limb compression to
reduce muscle perfusion/outflow. A series of unilateral elbow flexion muscle
contractions (30 repetitive contractions followed by 3 sets x 15 contractions)
was performed at 20% of 1RM with varying levels of external compression
(0 (without compression), 98, 121, and 147 mmHg external compression) around
the upper arm. Electromyography (EMG) signals were recorded from surface
electrodes placed on the biceps brachii muscle and analyzed for integrated
EMG (iEMG). Maximal voluntary isometric contraction (MVC) decreased similarly
during the control (0 mmHg) and 98 mmHg external compression bout (~18%);
the decline in MVC with 121 and 147 mmHg external compression was significantly
greater (~37%). Muscle activation increased progressively throughout the
contraction bout with each level of external compression, but iEMG was significantly
greater during 147 mmHg external compression. In conclusion, low-intensity
muscle contractions performed with external compression of 147 mmHg appears
to alter muscle perfusion/outflow leading to increased muscle activation
without decrements in work performed during the contraction bout.
Key words: Neuromuscular function, EMG, cuff pressure, biceps brachii, ischemia. |
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