Developing turns-amplitude clouds for healthy Chinese: reference values and influence factors

Abstract

Objective To establish the reference values and evaluate influence factors of turns-amplitude clouds for healthy Chinese. Methods We recruited 59 healthy subjects From July 2017 to December 2017 in Nanfang Hospital, Southern Medical University, including 34 males and 25 females, who were divided into young group (15-39 years old), middle-aged group (40-64 years old) and the elderly group (over 65 years), respectively. The number of turns (NT) and mean amplitude (MA) normative data of sternocleidomastoid muscle, deltoid muscle, biceps brachii muscle, extensor digitorum muscle, abductor digiti minimi muscle, quadriceps femoris muscle, tibialis anterior muscle, and gastrocnemius muscle were obtained by using concentric needle electrodes. A total of 20-30 records were collected from each muscle in different degree of contraction. A linear regression of lg(MA-100) versus lgNT was made and the slope, intercept, the 95% confidence interval of intercept, the largest MA and largest NT were calculated for each muscle. The influence factors, such as gender, age, muscles, and dominant limbs on the shape of cloud were evaluated by using the Chow breakpoint test. Results Normal turns-amplitude clouds were obtained and presented in this article. Muscle and age were found to be the main influence factors affecting the shape of cloud, and gender may affect some clouds, while the dominant limbs had little influence on the shape of the cloud. Conclusion The reference values of turns-amplitude cloud based on muscle, gender and age are of practical significance in clinic. Key words: Electromyography; Reference values; Turns-amplitude clouds