Handgrip force steadiness in young and older adults: a reproducibility study

Area of Science:

• Neurology
• Biomechanics
• Rehabilitation Science

Background:

• Force steadiness, a measure of muscle tonus control, predicts functional performance and correlates with motor impairment.
• Limited research exists on the validity of force steadiness measurements.
• Understanding handgrip force steadiness is crucial for assessing motor control and rehabilitation outcomes.

Purpose of the Study:

• To evaluate the reproducibility of handgrip force steadiness measurements.
• To assess age-related differences in handgrip force steadiness.
• To determine the clinical relevance of different force steadiness measures.

Main Methods:

• Test-retest design with a seven-day interval.
• Recruited ten young and thirty older adults.
• Measured handgrip steadiness at 5%, 10%, and 25% of maximum voluntary contraction (MVC) using the Nintendo Wii Balance Board (WBB).
• Calculated coefficients of variation (CVM, CVT) and Area between force curve and target line.

Main Results:

• Systematic improvement in steadiness observed between sessions for all measures.
• CVM and CVT at 5% MVC demonstrated good to high reliability (ICC > 0.75).
• Area measure showed poor reliability (ICC < 0.5).
• Young adults exhibited significantly better handgrip steadiness than older adults across all measures.

Conclusions:

• CVM and CVT measures show good reproducibility at lower MVCs using the WBB, suggesting clinical relevance.
• The Area measure is not a reliable indicator of force steadiness.
• Age is a significant factor, with younger individuals demonstrating superior handgrip steadiness.