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Cited by 69Muscle activation and electromyography studiesMotor Control and AdaptationMuscle Physiology and Disorders

Variability of quadriceps femoris motor neuron discharge and muscle force in human aging

Welsh, Seth J., Dinenno, Devin V., Tracy, Brian L.·2007·Experimental Brain Research
DOI 10.1007/s00221-006-0785-z
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Abstract

The purpose was to determine the contribution of visual feedback and the effect of aging on the variability of knee extensor (KE) muscle force and motor unit (MU) discharge. Single MUs were recorded during two types of isometric trials, (1) visual feedback provided (VIS) and then removed (NOVIS) during the trial (34 MUs from young, 32 from elderly), and (2) only NOVIS (66 MUs from young, 77 from elderly) during the trial. Recruitment threshold (RT) ranged from 0-37% MVC. Standard deviation (SD) and coefficient of variation (CV) of muscle force and MU interspike interval (ISI) was measured during steady contractions at target forces ranging from 0.3 to 54% MVC. Force drift (<0.5 Hz) was removed before analysis. VIS/NOVIS trials: the decrease in the CV of ISI from VIS to NOVIS was greater for MUs from elderly (12.5 +/- 4.1 to 9.94 +/- 2.6%) than young (10.6 +/- 3.3 to 10.3 +/- 2.8%, age group x vision interaction, P = 0.006). The change in CV of force from VIS to NOVIS was significantly greater for elderly (1.45 to 1.05%) than young (1.42 to 1.41%). NOVIS only trials: for all MUs, the average RT (6.6 +/- 7.7 % MVC), target force above RT (1.20 +/- 2.7% MVC), SD of ISI (0.012 +/- 0.005 s), and CV of ISI (11.1 +/- 3.3%) were similar for young and elderly MUs. The CV of force was similar between age groups for trials between 0 and 3% MVC (1.74 +/- 0.74%) and was greater for young subjects from 3 to 10% MVC (1.47 +/- 0.5 vs. 1.21 +/- 0.4%) and >10% MVC (1.44 +/- 0.6 vs. 1.01 +/- 0.3%). The CV of ISI was similar between age groups for MUs in 0-3, 3-10, and >10% bins of RT. Thus, the contribution of visuomotor correction to the variability of motor unit discharge and force is greater for elderly adults. The presence of visual feedback appears to be necessary to find greater discharge variability in motor units from the knee extensors of elderly adults.

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  • Discharges with interdischarge intervals < 33.3 or >250 ms were excluded because firing rates calculated from this range are unusually high (>30 Hz) or low (<4 Hz) for the VL muscle.

    “We excluded the discharges with interdischarge intervals < 33.3 or >250 ms because firing rates that calculated from this range of interdischarge intervals are unusually high (>30 Hz) or low (<4 Hz) for the VL muscle (7,20,21,30,31).”

    From Modulation of Neural and Muscular Adaptation Processes During Resistance Training by Fish Protein Ingestions in Older Adults (2020) · cites this paper as [31]

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Authors
Welsh, S. J., Dinenno, D. V., & Tracy, B. L.
Affiliations
Colorado State University (US)
Corresponding author
Tracy, Brian L.
ORCID
Tracy, Brian L.
Venue
Experimental Brain Research
Publisher
Springer Science and Business Media LLC
Published
2006-11-30
Volume
179
Issue
2
Pages
219-233
ISSN
  • 0014-4819 (ISSN-L)
  • 1432-1106
DOI
10.1007/s00221-006-0785-z
OpenAlex
W2161536851
Cited by
69
References
56
Citations by year
2026: 1 · 2025: 2 · 2024: 3 · 2023: 3 · 2022: 3 · 2021: 1 · 2020: 4 · 2019: 2 · 2018: 7 · 2017: 4 · 2016: 4 · 2015: 4 · 2014: 3 · 2013: 3 · 2012: 4
FWCI
2.30
Type
journal article
Language
en
Open access
closed
Licence
Locations
  • Experimental Brain Research (publishedVersion)
  • PubMed (publishedVersion)
Funders
  • National Institutes of Health
  • National Institute on Aging (K01AG019171, K01 AG19171)
Topics
  • Physical Sciences › Engineering › Biomedical Engineering › Muscle activation and electromyography studies
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Motor Control and Adaptation
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
Keywords
aging, visual feedback, knee extensors, motor unit recruitment threshold, coefficient of variation, isometric contraction
MeSH terms
Action Potentials, Adolescent, Adult, Aged, Aging, Feedback, Female, Humans, Knee, Male, Motor Neurons, Muscle Contraction, Psychomotor Performance, Recruitment, Neurophysiological, Muscle, Skeletal, Muscle Fibers, Skeletal

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