The acute effects of action observation on muscle strength/weakness and corticospinal excitability in older adults

Kylie K. Harmon, Ryan M. Girts, Jason I. Pagan, Gabriela Rodriguez, Matt S. Stock

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Muscle weakness is a critical problem facing many older adults. Interventions targeting nervous system plasticity may show promise in enhancing strength. The purpose of this study was to examine the acute effects of action observation on muscular strength characteristics and corticospinal excitability in older adults. Isometric wrist flexion strength characteristics and corticospinal excitability of the first dorsal interosseous (FDI) were measured in 14 older adults (mean age = 73 years) in response to observation of (1) STRONG contractions of the hand/wrist, (2) WEAK contractions of the hand/wrist, and (3) a CONTROL condition. Results from repeated measures analyses of variance (ANOVAs) indicated that rate of torque development at 200 ms (RTD200) significantly decreased from PRE to POST observation for CONTROL and WEAK, but not STRONG. No other ANOVAs were significant. However, effect sizes indicated that maximal voluntary contraction (MVC) peak torque showed moderate declines following WEAK (d = − 0.571) and CONTROL (d = − 0.636), but not STRONG (d = 0.024). Similarly, rate of torque development at 30 (RTD30), 50 (RTD50), and 200 (RTD200) ms showed large declines from PRE to POST after WEAK and CONTROL, but small changes following STRONG. FDI motor-evoked potential (MEP) amplitude tended to increase over time, but these results were variable. There was a pronounced effect from PRE to 8MIN (d = 0.954) during all conditions. Action observation of strong contractions may exert a preservatory effect on muscular strength. More work is needed to determine whether this is modulated by increased corticospinal excitability. The study was prospectively registered (ClinicalTrials.gov Identifier: NCT03946709).

Original languageEnglish (US)
Pages (from-to)1801-1810
Number of pages10
JournalExperimental Brain Research
Volume240
Issue number6
DOIs
StatePublished - Jun 2022
Externally publishedYes

Keywords

  • Mirror neuron system
  • Muscular weakness
  • Neuromuscular system
  • Transcranial magnetic stimulation

ASJC Scopus subject areas

  • General Neuroscience

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