Changes of Compound Muscle Action Potential after Low-Intensity Exercise with Transient Restriction of Blood Flow: a Randomized, Placebo-Controlled Trial

• Published in: Journal of Physical Therapy Science Vol. 21; no. 4; pp. 361 - 366
• Main Author: Kim, Laurentius Jongsoon
• Format: Journal Article
• Language: English
• Published: The Society of Physical Therapy Science 2009
• Subjects: Compound muscle action potential; Restriction of blood flow
• ISSN: 0915-5287; 2187-5626; 2187-5626
• DOI: 10.1589/jpts.21.361

[Purpose] The purpose of this study was to investigate the mechanism of muscular force improvement after low-intensity exercise with transient restriction of blood flow using compound muscle action potential (CMAP) analysis. [Subjects] Thirty healthy subjects in their 20s (mean age=21.73 years) were randomly assigned to an experimental group (EG) and a placebo control group (PG); each group had 15 subjects. [Methods] CMAP was analyzed by measuring terminal latency and amplitude using a motor nerve conduction velocity test. For Baseline 1, supramaximal electrical stimulation was applied to the median nerves of the EG and PG to obtain CMAP at the abductor pollicis brevis. For Baseline 2, the intensity of the electrical stimulation was decreased to a level at which the CMAP amplitude was about a third (1/3) of the CMAP amplitude obtained by supramaximal electrical stimulation. In the first test, CMAP was obtained under the same conditions as Baseline 2 after low-intensity thumb abduction exercises were performed at subjects' own pace for one minute. EG had blood flow restricted by a sphygmomanometer cuff, but PG did not. In the retest, CMAP was obtained under the same conditions as Baseline 2, one minute after the removal of the sphygmomanometer cuff immediately after the first test. [Results] PG did not show significant changes in CMAP, whereas EG showed a significant increase in CMAP amplitude, signifying that more muscle fibers were recruited. [Conclusion] This study found that low-intensity exercise with transient restriction of blood flow recruited more muscle fibers than low-intensity exercise without transient restriction of blood flow.