Association between force fluctuation during isometric ankle abduction and variability of neural drive in peroneus muscles

• Published in: Journal of electromyography and kinesiology 2023-06, Vol.70, p.102780-102780, Article 102780
• Main Authors: Kunugi, Shun, Hirono, Tetsuya, Yoshimura, Akane, Holobar, Aleš, Watanabe, Kohei
• Format: Article
• Language: English
• Subjects: Ankle abduction; EMG; Force fluctuation; Motor unit, peroneus muscles
• ISSN: 1050-6411; 1873-5711
• DOI: 10.1016/j.jelekin.2023.102780

Analyzing motor unit (MU) activities of peroneus muscles may reveal the causes of force control deficits of ankle eversion. This study aimed to examine peroneus muscles’ MU discharge characteristics and associations between force fluctuation and variability of the neural drive in healthy participants. Thirty-one healthy males participated in this study. MU activities were identified from high-density surface electromyography of peroneus muscles during ankle eversion at 15 and 30% of maximal voluntary contraction (MVC). Participants increased the contraction level until reaching the target and held it for 15 s. The central 10 s of the hold phase were used for analysis. A cumulative spike train (CST) was calculated using MU firings. Variabilities of the force and CST are represented by the coefficient of variation (CoV). Spearman’s rank correlation coefficient was used to assess the association between CoV of force and CoV of CST. For 15 and 30 % MVC trials, CoV of force was 1.86 ± 1.59 and 1.57 ± 1.26%, and CoV of CST was 5.01 ± 3.24 and 4.51 ± 2.78%, respectively. The correlation was significant at 15% (rho = 0.27, p