Reassessment of isometric muscle force complexity under different contraction intensities, joint angles, and visual feedback conditions.

IF 2.8 3区医学 Q2 PHYSIOLOGY

European Journal of Applied Physiology Pub Date : 2025-07-01 DOI:10.1007/s00421-025-05880-5

Ellen Pereira Zambalde, Carina Marconi Germer, Ricardo Gonçalves Molinari, Francesco Negro, Jakob Dideriksen, Leonardo Abdala Elias

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引用次数: 0

Abstract

Purpose: We employed an optimization method for the approximate entropy (ApEn) parameters ( $m$ , $r$ ) to evaluate the influence of changes in contraction intensity, visual feedback conditions, and joint angles in force ApEn during an isometric force-matching task.

Methods: Seventeen participants performed an index finger abduction isometric force task in six contraction intensities (5-75% of maximum voluntary contraction, MVC), with and without visual feedback of the force, and in three different metacarpophalangeal (MCP) joint angles. Force variability, complexity (ApEn), and power spectrum density (PSD) were assessed, and a correlation analysis was performed between these variables.

Results: The best ApEn ( $m$ , $r$ ) pair for muscle force analysis was $m = 2$ and $r = 0.20 \times$ force standard deviation (SD). Visual feedback influenced the ApEn; however, the comparison between experimental conditions (force intensity and joint angle) was similar. Both the force ApEn and the coefficient of variation (CoV) were reduced as a function of contraction intensity and without visual feedback. Conversely, the force SD and the PSD in the low-frequency band increased with contraction intensity and the absence of visual feedback. The changes in the MCP joint angle affected the MVC values and force CoV, with no significant effect on the force ApEn. The PSD in the low-frequency band (< 5 Hz) showed a strong negative correlation with force ApEn in both visual feedback conditions.

Conclusion: ApEn is influenced by force level and visual feedback, and it is strongly correlated with low-frequency force oscillations, which are related to the muscle's common drive.

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在不同收缩强度、关节角度和视觉反馈条件下对等长肌力复杂性的重新评估。

目的：我们采用近似熵（ApEn）参数（m, r）的优化方法来评估在等长力匹配任务中，收缩强度、视觉反馈条件和关节角度的变化对ApEn力的影响。方法：17名参与者在6种收缩强度（5-75%的最大自主收缩，MVC），有和没有视觉反馈的情况下，在3种不同的掌指关节（MCP）角度下进行食指外展等力任务。评估力变异性、复杂性（ApEn）和功率谱密度（PSD），并对这些变量进行相关性分析。结果：肌力分析的最佳ApEn （m, r）对为m = 2, r = 0.20 ×力标准差（SD）。视觉反馈影响ApEn；然而，实验条件（力强度和关节角度）的比较是相似的。在没有视觉反馈的情况下，力ApEn和变异系数（CoV）都作为收缩强度的函数而减小。相反，低频区的力SD和PSD随着收缩强度和视觉反馈的缺失而增加。MCP关节角度的变化对MVC值和力CoV有影响，对力ApEn无显著影响。结论：ApEn受力水平和视觉反馈的影响，且与低频力振荡密切相关，低频力振荡与肌肉共同驱动有关。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

European Journal of Applied Physiology 医学-生理学

CiteScore

6.00

自引率

6.70%

发文量

227

审稿时长

3 months

期刊介绍： The European Journal of Applied Physiology (EJAP) aims to promote mechanistic advances in human integrative and translational physiology. Physiology is viewed broadly, having overlapping context with related disciplines such as biomechanics, biochemistry, endocrinology, ergonomics, immunology, motor control, and nutrition. EJAP welcomes studies dealing with physical exercise, training and performance. Studies addressing physiological mechanisms are preferred over descriptive studies. Papers dealing with animal models or pathophysiological conditions are not excluded from consideration, but must be clearly relevant to human physiology.