Establishment of Clouds of Envelope Amplitude-Activity and Number of Small Segments-Activity in Normal Adults

OBJECTIVE: To establish the envelope amplitude-activity and number of small segments (NSS)-activity clouds of normal adults using the interference pattern of quantitative electromyography (EMG). METHOD: Healthy adults whose ages were from 20 to 59 years old participated in this study. Using quantitative EMG of the biceps brachii, vastus medialis, and tibialis anterior muscle, the interference patterns were analyzed. The interference patterns were measured at three to five different force levels, ranging from minimum to maximum, and recorded at least 20 epochs at each muscle. RESULTS: The envelope amplitude-activity and NSS-activity ratio of the biceps brachii, vastus medialis, and tibialis anterior muscles were obtained in males and females. The establishment of normal clouds of gender related envelope amplitude-activity and NSS-activity were obtained. CONCLUSION: By using the above normal clouds of envelope amplitude-activity and NSS-activity, automatic interference pattern analysis may contribute to early diagnosis and detection of progress of myopathy and neuropathy.

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

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.