Determinants of Manual Dexterity in Young Adults

The time to complete a test of manual dexterity (Grooved Pegboard Test) increases with advancing age due to changes in force steadiness, muscle strength, and cognitive function. However, the relative significance of these predictors among healthy young adults remains unknown. PURPOSE: To identify predictor variables that can explain the variance in the time that it takes young adults to complete the Grooved Pegboard Test. It was hypothesized that an expanded set of force steadiness tests, as well an assessment of cognitive function, would predict a significant amount of the variance in pegboard times. METHODS: Twenty-seven young adults (23.8 ± 4.0 years) performed three trials of the Grooved Pegboard Test with the right (dominant) hand. Strength was measured for handgrip, wrist extension, pinch, and index finger abduction tasks. Force steadiness measurements were made at 5% and 10% of maximum during traditional one-joint tests (wrist extension, index finger abduction, and pinch) as well as during novel two-joint tests (wrist extension combined with either index finger abduction or pinch tasks). Cognitive function was assessed using a test of reaction time. RESULTS: 1) Time to complete the Grooved Pegboard Test was 52.5 ± 4.8 s (range: 42.3 - 63.5 s). 2) Force steadiness was worse for two-joint tests (3.78 ± 1.23%) than one-joint tests (2.50 ± 0.71%, P \u3c 0.001). 3) Force steadiness was negatively correlated with pegboard times in 13 of 14 tests (e.g., wrist extension at 10%, r = -0.452, P \u3c 0.01). 4) No significant correlation was observed with either reaction time or strength and pegboard times. 5) Multiple regression analysis explained 37% of the variance in times to complete the Grooved Pegboard Test using a model containing a single one-joint test and two of the two-joint force steadiness tests. CONCLUSIONS: The use of an expanded set of steadiness tests significantly improved the ability to predict pegboard times among young adults. Nonetheless, a substantial amount of the variance in the pegboard times for young adults remains unexplained