Age-independent Decline in Manual Dexterity of Middle-aged and Older Adults

Study Overview
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Brief Summary
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The objective of the clinical trial is to evaluate the mediating influence of force control on the pegboard times of adults (50-89 years) who are stratified into groups of faster and slower pegboard times. The hypothesis is that practice of either a pegboard test or a force-control task will reduce pegboard times, but the decrease will be greater and less similar after the two practice interventions for the slower group of participants. The outcomes are expected to demonstrate that force control is a modifiable mediator of pegboard times for this cohort, but the effect will be stronger for the group with faster pegboard times.

Detailed Description
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The study will involve a randomized, cross-over design with a one-week washout between arms. The two arms (3 weeks each) will comprise practice of the grooved pegboard test and practice of steady contractions while lifting and lowering light loads with a hand muscle. Randomization into practice order will be accomplished with a block approach (block size = 4) for each of the two groups. The outcome assessors will be blinded to practice order. The outcomes will comprise three tests of manual dexterity and the measurement of force control during submaximal contractions. The outcomes will be obtained before and after the six sessions in each practice arm.

Official Title
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Age-independent Decline in Manual Dexterity of Middle-aged and Older Adults

Conditions
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Aging

Intervention / Treatment
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* Other: Pegboard practice
* Other: Force control practice


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Able to read, write, and speak English Able to arrange transportation to the Boulder campus Exclusion Criteria: Cognitive impairment Major psychiatric condition Unstable depressive disorder Progressive neurological, muscular, cardiovascular, or skeletal disorder Chronic pain condition Currently taking medication known to influence neuromuscular function Recent hospitalization Unable to attend 12 practice sessions in 6 weeks

Ages Eligible for Study
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Minimum Age: 50 Years
Maximum Age: 89 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Faster<br>This group will comprise participants who complete the grooved pegboard test at baseline with a time of less than 71 seconds. One half of the members in this group will perform the two interventions in the order of pegboard practice and then force control practice, whereas the other half of the group will perform the two practice interventions in the opposite order. | Other: Pegboard practice<br>* Practice of the grooved pegboard test<br>Other: Force control practice<br>* Practice performing steady muscle contractions<br>|
| Experimental: Slower<br>This group will comprise participants who complete the grooved pegboard test at baseline with a time of greater than 70 seconds. One half of the members in this group will perform the two interventions in the order of pegboard practice and then force control practice, whereas the other half of the group will perform the two practice interventions in the opposite order. | Other: Pegboard practice<br>* Practice of the grooved pegboard test<br>Other: Force control practice<br>* Practice performing steady muscle contractions<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Grooved pegboard test | Time to complete the test as quickly as possible | Changes from baseline (week 1) at weeks 4 and 7 | 
| 9-hole pegboard test | Time to complete the test as quickly as possible | Changes from baseline (week 1) at weeks 4 and 7 | 
| Jebsen Hand Function test | Time to complete the test as quickly as possible | Changes from baseline (week 1) at weeks 4 and 7 | 
| Force control | The coefficient of variation for force when subjects exert a constant submaximal force | Changes from baseline (week 1) at weeks 4 and 7 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| EMG amplitude | Absolute amplitude of the electromyographic (EMG) signal for the involved muscles during the steady contractions | Changes from baseline (week 1) at weeks 4 and 7 | 
| MVC force | The peak force exerted during a maximal isometric contractions | Changes from baseline (week 1) at weeks 4 and 7 | 
| 1-RM load | The maximal weight that can be lifted once | Changes from baseline (week 1) at weeks 4 and 7 | 
| Index finger acceleration | The average standard deviation of index finger acceleration in the abduction-adduction plane when a light load is being lifted and lowered during the practice intervention | Changes from baseline (week 1) at weeks 4 and 7 | 
| Motor unit discharge rates | The discharge times of action potentials by motor units during the steady submaximal contractions | Changes from baseline (week 1) at weeks 4 and 7 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Manual dexterity