Effects of Vascular Occlusion on Surface Electromyography and Muscle Oxygenation during Isometric Contraction

in Journal of Sport Rehabilitation
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Objective:

To investigate changes in motor-unit activity and muscle oxygenation (MO) during isometric contraction with and without vascular occlusion using surface electromyography (EMG) and near-infrared spectroscopy.

Design and Setting:

MO and EMG of the right vastus medialis muscle were measured during isometric contraction at 30%, 50%, and 70% maximal voluntary contraction (MVC), with and without vascular occlusion.

Participants:

6 healthy men.

Results:

Integrated EMG (IEMG) and mean power frequency were significantly higher with vascular occlusion at 30% and 50% MVC. MO reduction at each load was significantly lower with vascular occlusion. A significant positive correlation was found between IEMG and changes in MO level under both conditions.

Conclusions:

These results suggest that oxygen supply to active muscles was impaired by occlusion and that type II fibers were then preferentially recruited, which suggests that hypertrophy occurs in low-intensity exercise in patients with limitations resulting from advanced age, pain, or postsurgery limitation.

Yamada and Tanaka are with the Dept of Rehabilitation; Kusaka, the Maternal and Perinatal Center; Mori and Norimatsu, the Dept of Orthopedic Surgery; and Itoh, the Dept of Pediatrics, Faculty of Medicine, Kagawa University, Kagawa, Japan 761-0793.