Citation

Valenza A, Charlier H, Bianco A, Filingeri D. Am. J. Physiol. Regul. Integr. Comp. Physiol. 2020; ePub(ePub): ePub.

Copyright

(Copyright © 2020, American Physiological Society)

DOI

10.1152/ajpregu.00226.2020

PMID

33074012

Abstract

Many occupations and sports require high levels of manual dexterity under thermal stress and mental fatigue. Yet, multi-stressor studies remain scarce. We quantified the interactive effects of thermal stress and mental fatigue on manual dexterity. Seven males (21.1±1.3y) underwent 6 separate 60-min trials characterised by a combination of 3 air temperatures (HOT: 37°C; NEUTRAL: 21°C; COLD: 7°C) and 2 mental fatigue states (MF: mental fatigue induced by a 35-min cognitive battery; No-MF: no mental fatigue). Participants performed complex (O'Connor test) and simple (Hand-Tool test) manual tasks pre- and post-trials to determine stressors-induced performance changes. We monitored participants' rectal temperature and hand skin temperature (Thand) continuously and assessed reaction time (Hand-Click test) and subjective mental fatigue (5-point scale). Thermal stress (p<0.0001), but not mental fatigue (p=0.290), modulated Thand (HEAT: +3.3°C [95%CI +0.2, +6.5]; COLD: -7.5°C [-10.7, -4.4]). Mental fatigue (p=0.021), but not thermal stress (p=0.646), slowed reaction time (~10%) and increased subjective fatigue. Thermal stress and mental fatigue had an interactive effect on the complex manual task (p=0.040), with COLD-No-MF decreasing performance by -22% [-39, -5], while NEUTRAL-MF, COLD-MF, and HEAT-MF by -36% [-53, -19], -34% [-52, -17], and -36% [-53, -19], respectively. Only mental fatigue decreased performance in the simple manual task (-30% [-43, -16] across all thermal conditions; p=0.002). Cold stress-induced impairments in complex manipulation increase with mental fatigue; yet combined stressors' effects are no greater than that of mental fatigue alone, which also impairs simple manipulation. Mental fatigue poses a greater challenge to manual dexterity than thermal stress.

Language: en

Keywords

Hot Temperature; Cold Temperature; Hand; Mental Fatigue; Physical Functional Performance