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Oscillations in neural drive and age-related reductions in force steadiness with a cognitive challenge. J Appl Physiol (1985) 2019 04 01;126(4):1056-1065

Date

03/01/2019

Pubmed ID

30817244

Pubmed Central ID

PMC6485692

DOI

10.1152/japplphysiol.00821.2018

Scopus ID

2-s2.0-85064927350   9 Citations

Abstract

A cognitive challenge when imposed during a low-force isometric contraction will exacerbate sex- and age-related decreases in force steadiness, but the mechanism is not known. We determined the role of oscillations in the common synaptic input to motor units on force steadiness during a muscle contraction with a concurrent cognitive challenge. Forty-nine young adults (19-30 yr; 25 women, 24 men) and 36 old adults (60-85 yr; 19 women, 17 men) performed a cognitive challenge (counting backward by 13) during an isometric elbow flexion task at 5% of maximal voluntary contraction. Single-motor units were decomposed from high-density surface EMG recordings. For a subgroup of participants, motor units were matched during control and cognitive challenge trials, so the same motor unit was analyzed across conditions. Reduced force steadiness was associated with greater oscillations in the synaptic input to motor units during both control and cognitive challenge trials ( r = 0.45-0.47, P < 0.01). Old adults and young women showed greater oscillations in the common synaptic input to motor units and decreased force steadiness when the cognitive challenge was imposed, but young men showed no change across conditions (session × age × sex, P < 0.05). Oscillations in the common synaptic input to motor units is a potential mechanism for altered force steadiness when a cognitive challenge is imposed during low-force contractions in young women and old adults. NEW & NOTEWORTHY We found that oscillations in the common synaptic input to motor units were associated with a reduction in force steadiness when a cognitive challenge was imposed during low-force contractions of the elbow flexor muscles in young women and old men and women but not young men. Age- and sex-related muscle weakness was associated with these changes.

Author List

Pereira HM, Schlinder-DeLap B, Keenan KG, Negro F, Farina D, Hyngstrom AS, Nielson KA, Hunter SK

Authors

Allison Hyngstrom PhD Associate Professor in the Physical Therapy department at Marquette University
Kristy Nielson PhD Professor in the Psychology department at Marquette University




MESH terms used to index this publication - Major topics in bold

Adult
Aged
Aging
Cognition
Elbow
Electromyography
Female
Humans
Isometric Contraction
Male
Motor Neurons
Muscle Strength
Muscle, Skeletal
Young Adult