Electromyographic Analysis of Gesture Execution and Actual Tool Use in Healthy Adults

Assessments based solely on gesture execution may not reproduce the sensory and biomechanical demands of actual tool use. This study compared upper-limb muscle activation during gesture execution (GE) and actual tool use (AU) in 52 healthy adults in their twenties performing five tasks derived from the Florida Apraxia Screening Test-Revised: sprinkling salt, drinking water, stirring coffee, combing hair, and writing. Surface electromyography was recorded from eight muscles of the dominant right upper limb. Because GE and AU were obtained from the same participants, primary comparisons were performed using two-sided paired-samples t tests. Family-wise error across 40 muscle-by-task comparisons was controlled using the Holm procedure, and mean paired differences, 95% confidence intervals, p values, and Cohen’s dz were reported. After Holm adjustment, 18 of 40 comparisons were significant (absolute dz = 0.52–1.62). GE showed greater anterior deltoid activation in Tasks 1, 2, 3, and 5 and greater biceps and triceps activation in Task 3. AU showed greater extensor carpi radialis and extensor digitorum activation in Task 2; greater activation of all measured wrist and finger muscles in Task 4; and greater posterior deltoid, triceps, wrist, and finger muscle activation in Task 5. These findings demonstrate task- and muscle-specific differences in normalized EMG amplitude between GE and AU. The observed differences may be associated with physical interaction during AU, but the underlying biomechanical and sensorimotor mechanisms were not directly measured. The results provide exploratory reference data from healthy young adults for future studies comparing representational and actual tool-use conditions.