Repetitive eccentric muscle contractions increase torque unsteadiness in the human triceps brachii

Andrew J Meszaros; Masaki Iguchi; Shuo-Hsiu Chang; Richard K Shields

doi:10.1016/j.jelekin.2009.12.001

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Repetitive eccentric muscle contractions increase torque unsteadiness in the human triceps brachii

Journal article

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Repetitive eccentric muscle contractions increase torque unsteadiness in the human triceps brachii

Andrew J Meszaros, Masaki Iguchi, Shuo-Hsiu Chang and Richard K Shields

Journal of electromyography and kinesiology, Vol.20(4), pp.619-626

2010

DOI: 10.1016/j.jelekin.2009.12.001

PMCID: PMC2875352

PMID: 20060317

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https://www.ncbi.nlm.nih.gov/pmc/articles/2875352View

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Abstract

Torque steadiness and low-frequency fatigue (LFF) were examined in the human triceps brachii after concentric or eccentric fatigue protocols. Healthy young males ( n = 17) performed either concentric or eccentric elbow extensor contractions until the eccentric maximal voluntary torque decreased to 75% of pre-fatigue for both (concentric and eccentric) protocols. The number of concentric contractions was greater than the number of eccentric contractions needed to induce the same 25% decrease in eccentric MVC torque (52.2 ± 2.9 vs. 41.5 ± 2.1 for the concentric and eccentric protocols, respectively, p < .01). The extent of peripheral fatigue was ∼12% greater after the concentric compared to the eccentric protocol (twitch amplitude), whereas LFF (increase in double pulse torque/single pulse torque), was similar across protocols. Steadiness, or the ability for a subject to hold a submaximal isometric contraction, was ∼20 % more impaired during the Ecc protocol ( p = .052). Similarly, the EMG activity required to hold the torque steady was nearly 20% greater after the eccentric compared to concentric protocol. These findings support that task dependent eccentric contractions preferentially alter CNS control during a precision based steadiness task.

Low-frequency fatigue

Muscle fatigue

Concentric and eccentric contractions

Force fluctuation

Triceps brachii

Details

Title: Subtitle: Repetitive eccentric muscle contractions increase torque unsteadiness in the human triceps brachii
Creators: Andrew J Meszaros - Neuroscience Department, College of Medicine, University of Toledo, Toledo, OH, USA
Masaki Iguchi - Physical Therapy and Rehabilitation Science, Carver College of Medicine, The University of Iowa, Iowa City, IA, USA
Shuo-Hsiu Chang - Physical Therapy and Rehabilitation Science, Carver College of Medicine, The University of Iowa, Iowa City, IA, USA
Richard K Shields - Physical Therapy and Rehabilitation Science, Carver College of Medicine, The University of Iowa, Iowa City, IA, USA
Resource Type: Journal article
Publication Details: Journal of electromyography and kinesiology, Vol.20(4), pp.619-626
DOI: 10.1016/j.jelekin.2009.12.001
PMID: 20060317
PMCID: PMC2875352
NLM abbreviation: J Electromyogr Kinesiol
ISSN: 1050-6411
eISSN: 1873-5711
Publisher: Elsevier Ltd
Language: English
Date published: 2010
Academic Unit: Orthopedics and Rehabilitation; Physical Therapy and Rehabilitation Science
Record Identifier: 9984047731402771

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