Neural Substrates Underlying Adaptations in Manual Dexterity of Older Adults

NCT ID: NCT07011160

Last Updated: 2025-06-08

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

NOT_YET_RECRUITING

Clinical Phase

NA

Total Enrollment

72 participants

Study Classification

INTERVENTIONAL

Study Start Date

2026-04-01

Study Completion Date

2030-03-30

Brief Summary

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Age-related declines in motor function can compromise independence and quality of life. This project examines how practice and somatosensory stimulation reshape the neural control of hand muscles in older adults, leveraging neuroplasticity to enhance dexterity. By identifying modifiable neural mechanisms that underlie improved motor performance, this research lays the groundwork for targeted, non-invasive interventions that can be translated into clinical and community settings to support healthy aging and functional independence.

Detailed Description

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Managing fine motor function is essential for independence and quality of life in older adults. However, the neural mechanisms underlying age-related declines in manual dexterity remain poorly understood. Traditional models of motor control suggest that the nervous system coordinates movement through shared motor commands across muscles-so-called "motor modules" or "muscle synergies". Yet, emerging evidence reveals that synaptic inputs to motor neurons can vary even within a single muscle, challenging this muscle-level concept and prompting a shift toward more a granular, motor-unit level framework. These "motor unit modes" offer a more accurate representation of the neural architecture of motor control.

This project will be the first to investigate whether improvements in manual dexterity-a core marker of neurological health in aging-are associated with neuroplastic changes in the strength of functionally relevant motor unit modes. Older adults (54-89 yrs) will practice a test of manual dexterity (Grooved Pegboard) with or without performance-enhancing transcutaneous electrical nerve stimulation (TENS). Outcomes will include force steadiness and motor unit activity derived from high-density electromyography during low-intensity contractions.

Our central hypothesis is that improvements in manual dexterity will be mediated by neuroplastic strengthening of functionally relevant motor unit modes. The project has three specific aims:

1. Characterize short-term neuroplastic adaptations following task familiarization.
2. Determine the effects of steady-contraction training on neuromuscular control.
3. Evaluate the added benefit of somatosensory augmentation with TENS.

Innovation. This study introduces two key innovations: (1) It quantifies, for the first time, the extent to which improvements in a dynamic behavior are mediated by changes in shared synaptic inputs across motor units during low-intensity contractions; (2) it evaluates the capacity of TENS-induced somatosensory feedback to boost neuroplasticity in the aging motor system.

Expected Outcomes. We expect that gains in force steadiness and pegboard performance will strongly correlate with increased strength and consistency of motor unit modes. These findings will clarify the neural mechanisms underlying motor adaptation in older adults and define new markers for assessing motor function.

Impact. Aligned with the goals of PA-25-303 and the missions of NINDS and NIA, this research will generate foundational knowledge of spinal motor control and establish motor unit modes as a new biomarker for evaluating motor function and therapeutic efficacy. This work has the potential to inform targeted interventions aimed at preserving dexterity and independence in older individuals and those with neurological dysfunction.

Conditions

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Aging Hands

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

SEQUENTIAL

Primary Study Purpose

BASIC_SCIENCE

Blinding Strategy

DOUBLE

Participants Outcome Assessors

Study Groups

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Pegboard time

Participants will be assigned to a group of slow or fast improvers based on the decrease in pegboard time after an initial familiarization session.

Group Type EXPERIMENTAL

Familiarization

Intervention Type BEHAVIORAL

Participants will perform 25 trials of the Grooved Pegboard Test

Force-steadiness practice

Participants will complete three training sessions in which they perform force-steadiness tasks either alone (sham) or paired with transcutaneous electrical nerve stimulation (TENS). One-half of the participants in each improver group will be to each of these practice groups.

Group Type EXPERIMENTAL

Transcutaneous electrical nerve stimulation (TENS)

Intervention Type BEHAVIORAL

Force-steadiness training will be performance either without (sham) or paired with TENS.

Interventions

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Transcutaneous electrical nerve stimulation (TENS)

Force-steadiness training will be performance either without (sham) or paired with TENS.

Intervention Type BEHAVIORAL

Familiarization

Participants will perform 25 trials of the Grooved Pegboard Test

Intervention Type BEHAVIORAL

Eligibility Criteria

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Inclusion Criteria

Community-dwelling men and women who are 54-89 years of age and able to give fully informed consent; able to read, write, and speak English to ensure safe participation in the project; and able to arrange own transportation to Boulder campus.

Exclusion Criteria

Cognitive impairment, major psychiatric condition, or unstable depressive disorder that would influence the ability to understand the study and cooperate fully in the proposed protocols; any progressive neurological, muscular, cardiovascular, or skeletal disorder that limits participation, such as (but not limited to) (1) amyotrophic lateral sclerosis, multiple sclerosis, multiple system atrophy, muscular dystrophy, myasthenia gravis, Parkinson's disease, spinal muscular atrophy, spinocerebellar ataxia, or spasticity; (2) congenital, mitochondrial, or thyrotoxic myopathies, fibromyalgia, or myositis; (3) peripheral neuropathy, diabetes, or hypertension; or (4) cancer, gout, osteoarthritis with severe pain, or rheumatoid arthritis; chronic pain condition that would impair the ability to participate in the study; currently taking prescribed medication known to influence neuromuscular function, such as carisoprodol, cyclobenzaprine, metaxalone, and methocarbamol; function-limiting injury to the hands, arms, shoulders, neck, or legs; recent hospitalization (within the last 3 months) or enforced bedrest/sedentary state; inability to attend the evaluation and practice sessions in 2 weeks.
Minimum Eligible Age

54 Years

Maximum Eligible Age

89 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

Yes

Sponsors

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University of Colorado, Boulder

OTHER

Sponsor Role lead

Responsible Party

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Roger Enoka

PI

Responsibility Role PRINCIPAL_INVESTIGATOR

Principal Investigators

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Roger M Enoka, PhD

Role: PRINCIPAL_INVESTIGATOR

University of Colorado, Boulder

Locations

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University of Colorado Boulder

Boulder, Colorado, United States

Site Status

Countries

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United States

Central Contacts

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Roger Enoka, PhD

Role: CONTACT

13039219325

Mélanie Henry, PhD

Role: CONTACT

Facility Contacts

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Roger Enoka

Role: primary

3039219325

Mélanie Henry, PhD

Role: backup

References

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Tvrdy T, Henry M, Enoka RM. Influence of the variability in motor unit discharge times and neural drive on force steadiness during submaximal contractions with a hand muscle. J Neurophysiol. 2025 Feb 1;133(2):697-708. doi: 10.1152/jn.00333.2024. Epub 2025 Jan 17.

Reference Type BACKGROUND
PMID: 39823197 (View on PubMed)

Daneshgar S, Tvrdy T, Enoka RM. Explaining the influence of practice on the grooved pegboard times of older adults: role of force steadiness. Exp Brain Res. 2024 Aug;242(8):1971-1982. doi: 10.1007/s00221-024-06878-9. Epub 2024 Jun 25.

Reference Type BACKGROUND
PMID: 38916760 (View on PubMed)

Daneshgar S, Tvrdy T, Enoka RM. Practice-Induced Changes in Manual Dexterity of Older Adults Depend on Initial Pegboard Time. Med Sci Sports Exerc. 2023 Nov 1;55(11):2045-2052. doi: 10.1249/MSS.0000000000003245. Epub 2023 Jun 27.

Reference Type BACKGROUND
PMID: 37379250 (View on PubMed)

Other Identifiers

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1R01NS141829-01A1

Identifier Type: -

Identifier Source: org_study_id

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