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.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Practice of the grooved pegboard test
Practice performing steady muscle contractions
University of Colorado Boulder
Boulder, Colorado, United States
Grooved pegboard test
Time to complete the test as quickly as possible
Time frame: Changes from baseline (week 1) at weeks 4 and 7
9-hole pegboard test
Time to complete the test as quickly as possible
Time frame: Changes from baseline (week 1) at weeks 4 and 7
Jebsen Hand Function test
Time to complete the test as quickly as possible
Time frame: 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
Time frame: Changes from baseline (week 1) at weeks 4 and 7
EMG amplitude
Absolute amplitude of the electromyographic (EMG) signal for the involved muscles during the steady contractions
Time frame: Changes from baseline (week 1) at weeks 4 and 7
MVC force
The peak force exerted during a maximal isometric contractions
Time frame: Changes from baseline (week 1) at weeks 4 and 7
1-RM load
The maximal weight that can be lifted once
Time frame: 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
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Time frame: 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
Time frame: Changes from baseline (week 1) at weeks 4 and 7