Effects of Neuromuscular Electrical Stimulation on the Muscle Hypertrophy and Cross Training Effect.

, Han, Soo Jeong; , Kim, Jung Yeon; , Yoon, Tae Sik

Original Article

Journal of the Korean Academy of Rehabilitation Medicine 2006;30(6):655-660.

Han, Soo Jeong , Kim, Jung Yeon , Yoon, Tae Sik

Department of Rehabilitation Medicine, Ewha Womans University College of Medicine, Korea. mt-moon@hanmail.net

전기 자극에 대한 근육의 근 비대 및 교차훈련 효과

한수정, 김정연, 윤태식

이화여자대학교 의과대학 재활의학교실

Abstract

Objective
To evaluate the effect of electrical stimulation on muscle strength, muscle bulk and envelope amplitude.
Method
Twenty right handed healthy men and women (8：12) volunteered to be subjects whose mean age were 25.5⁑2.8 years. Left thenar muscle was stimulated at 40 Hz frequency for 20 minutes, every weekday for 2 weeks. Maximal tip pinch power of first and second finger, and cross sectional area of abductor pollicis brevis were assessed before and after electrical stimulation in both hands.
Results
Maximal tip pinch power increased in bilateral hands. The thickness and cross sectional area of both thenar muscles were increased, but they were significant only in left side. Envelope amplitude increased significantly in left thenar muscle at maximal voluntary contraction, and showed a tendency to increase in right side at each percent of 10, 30, 50, 100 and in left side at 10, 30, 50% maximal voluntary contractions.
Conclusion
The electrical stimulation on unilateral muscle induced the increment of bilateral muscular strength. The neural factor and muscle hypertrophy are responsible for the increased strength of the stimulated muscle and the increase in the nonstimulated muscle strength is related to the cross-training effect and adaptation effect. (J Korean Acad Rehab Med 2006; 30: 655-660)

Key Words: Electrical stimulation, Muscle hypertrophy, Cross training effect, Ultrasonography, Envelope amplitude