The Effects of Fatigue on Manual Dexterity

Abstract

Humans are uniquely adept at manipulating objects in their environment. Our ability to use our hands for dextrous skilled movements is unique in the animal kingdom and fundamental for us to successfully perform a myriad of everyday tasks. Even a seemingly simple task such as turning off an alarm clock is the result of a complex and dynamic interplay of sensory, cognitive, and physiological processes. Dextrous behaviours in young, healthy adults are well-characterised, but research has so far failed to establish how fatigue affects manual dexterity in this population. In this thesis, a series of studies was performed with the aim of revealing insights into how mental and neuromuscular fatigue affect the sensorimotor system in the context of dextrous actions. Three studies explored and critically examined existing paradigms for inducing mental fatigue, which were found to have numerous limitations. To address these limitations, study four validated a novel method to induce mental fatigue using a combination of subjective and behavioural measures. This novel method was then used in study five to investigate the effects of mental fatigue on a battery of dexterity tasks. The outcomes from this study indicated that mental fatigue has specific effects on dextrous behaviour which appear to be mediated through cognitive processes. Study six examined participants’ performance in the same three dexterity tasks after undergoing a neuromuscular fatigue intervention. Like study five, study six also found task-specific effects on dextrous behaviour, with the perceptual effects of neuromuscular fatigue appearing to have particular importance. Together, these studies show that the sensorimotor processes underlying manual dexterity are affected in specific ways by fatigue and that these effects are highly dependent on the origin of that fatigue. These novel findings extend prior research and provide a foundation for future research into how different types of fatigue could meaningfully impact the outcomes of dextrous tasks.