Fatigue-related modulation of low-frequency common drive to motor units

doi:10.1007/s00421-020-04363-z

中山醫學大學機構典藏 CSMUIR > 中山醫學大學研究成果 > 期刊論文 > Item 310902500/24558

Please use this identifier to cite or link to this item: https://ir.csmu.edu.tw:8080/ir/handle/310902500/24558

Title:	Fatigue-related modulation of low-frequency common drive to motor units
Authors:	Hwang, IS;Lin, YT;Huang, CC;Chen, YC
Keywords:	Fatigue;Firing rate;Discharge-force relation;Stabilogram diffusion analysis;EMG
Date:	2020
Issue Date:	2022-08-09T08:04:20Z (UTC)
Publisher:	SPRINGER
ISSN:	1439-6319
Abstract:	Purpose This study investigated fatigue-related modulation of common neural inputs to motor units (MUs) under 5 Hz, which determines force precision control. Methods Twenty-seven adults performed a sequence of fatiguing contractions. The participants were assessed with a static isometric index abduction at 20% maximal voluntary contraction in the pre-test and post-test. Discharge characteristics of MUs of the first dorsal interosseous muscle were analyzed with decomposed EMG signals. Results Along with increases in the mean (58.40 +/- 11.76 ms -> 62.55 +/- 10.83 ms, P = 0.029) and coefficient of variation (0.204 +/- .014 -> 0.215 +/- 0.017, P = 0.002) in inter-spike intervals, the fatiguing contraction caused reductions in the mean frequency (16.84 +/- 3.31 Hz -> 15.59 +/- 3.21 Hz, P = 0.027) and spectral dispersions (67.54 +/- 4.49 -> 62.64 +/- 6.76 Hz, P = 0.007) of common neural drive, as estimated with smoothed cumulative motor unit spike trains (SCMUSTs). Stabilogram diffusion analysis of SCMUSTs revealed significant fatigue-related reductions in the long-term effective diffusion coefficient (1.91 +/- 0.77 Hz(2)/s -> 1.61 +/- 0.61 Hz(2)/s, P = 0.020) and long-term scaling exponent (0.480 +/- 0.013 Hz(2)/s -> 0.471 +/- 0.017 Hz(2)/s, P = 0.014). After fatiguing contraction, mutual information of force fluctuations and SCMUSTs was augmented roughly by 12.95% (P = 0.041). Conclusions Muscular fatigue could compress and shift the low-frequency common drive to MUs toward lower spectral bands, thereby enhancing transmission of twitch forces through the muscle-tendon complex with a low-pass filter property. The fatigue-induced changes involve increased closed-loop control of the common modulation of MU discharge rates.
URI:	http://dx.doi.org/10.1007/s00421-020-04363-z https://www.webofscience.com/wos/woscc/full-record/WOS:000526232600002 https://ir.csmu.edu.tw:8080/handle/310902500/24558
Relation:	EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY ,2020 ,v120 ,issue 6 ,p1305-1317
Appears in Collections:	[中山醫學大學研究成果] 期刊論文

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