Associations among strength, steadiness, and hand function across the adult life span.

INTRODUCTION: Age-related differences in force steadiness have been extensively examined and used as an index of motor function. However, the functional relevance of steadiness remains unclear. PURPOSE: The aim here was to evaluate the relations among hand strength, steadiness, and function across the adult life span. METHODS: Seventy-five adults (45 women; 18-89 yr) performed three strength, two steadiness, and four functional tests with both hands. Strength was measured during index finger abduction, precision pinch, and handgrip, and steadiness was measured during index finger abduction and precision pinch. Functional tests included the Grooved Pegboard test, the game Operation™, a scissor task, and a tracing task. RESULTS: Moderate correlations were observed between both steadiness tasks and performance on the Grooved Pegboard test (R(2) = 0.57 and R(2) = 0.46, respectively) and Operation™ (R(2) = -0.47 and R(2) = -0.57, respectively). CONCLUSIONS: The relation between measures of steadiness and hand function suggests that the physiological mechanisms responsible for differences in steadiness also contribute to differences in the performance of fine motor tasks with the hand.