Exploring the relationship between effort perception and poststroke fatigue

Abstract

ObjectiveTo test the hypothesis—post-stroke fatigue, a chronic, pathologic fatigue condition, is driven by altered effort perception.ParticipantsFifty-eight non-depressed, mildly impaired stroke survivors with varying severity of fatigue completed the study.Main outcome measuresSelf-reported fatigue (trait and state), perceived effort—PE (explicit and implicit) and motor performance was measured in a handgrip task. Trait fatigue was measured using Fatigue Severity Scale-7 and Neurologic Fatigue Index. State fatigue was measured using a visual analogue scale (VAS). Length of hold at target force, overshoot above target force and force variability in handgrip task were measures of motor performance. PE was measured using a VAS (explicit PE) and line length estimation, a novel implicit measure of PE.ResultsRegression analysis showed 11.6% of variance in trait fatigue was explained by implicit PE (R = 0.34; p = 0.012). Greater fatigue related to longer length of hold at target force (R = 0.421; p < 0.001). A backward regression showed length of hold explained explicit PE in the 20% force condition (R = 0.306; p = 0.021) and length of hold and overshoot above target force, explained explicit PE in the 40% (R = 0.399; p = 0.014 & 0.004) force condition. In the 60% force condition, greater explicit PE was explained by higher force variability (R = 0.315; p = 0.017). None of the correlations were significant for state fatigue.ConclusionTrait fatigue, but not state fatigue, correlating with measures of perceived effort and motor performance may suggest that altered perception may lead to high fatigue mediated by changes in motor performance. This novel finding furthers our mechanistic understanding of post-stroke fatigue.

Effect of transcranial direct current stimulation on post-stroke fatigue

“…This measure takes advantage of the susceptibility of visual perception to physical effort where high effort unfavourably biases distance estimation [ 62 ]. On similar lines, a line length estimation task was developed and shown to be biased by prior exertion, which we use as a measure of implicit PE [ 21 , 63 ]. We showed that trait fatigue is explained by implicit PE but not explicit PE in a physical task [ 21 ].…”

“…PE was measured in an isometric handgrip task with a hand-held dynamometer (Biometrics Ltd, Newport, UK) performed using the dominant hand [ 21 ]. Force data from the dynamometer were acquired at 500 Hz via a data acquisition interface (Power1401, CED) and recorded in MATLAB (2016b, MathWorks).…”

“…Within this framework, expectations set the gain for afferent input and PE is a psychophysical output of the gain function [ 20 ]. We recently showed that those with greater PSF did indeed show greater PE [ 21 ]. Increased PE may be driven by altered gain, as measured by motor cortex excitability [ 20 ].…”

Effect of the subjective intensity of fatigue and interoception on perceptual regulation and performance during sustained physical activity

“…Alternative methods of quantifying the subjective perception of effort that are not based on self-reported assessment (e.g. De Doncker et al, 2020) or paradigms used to directly assess the influence of the subjective value of effort on behaviour (e.g. Massar et al, 2018) may provide a means of further substantiating the evidenced relationship between fatigue and effort perception and its subsequent effect on performance.…”

Effect of transcranial direct current stimulation on post-stroke fatigue

“…Perceived effort PE was measured in an isometric hand grip task with a hand-held dynamometer (Biometrics Ltd, Newport, UK) performed using the dominant hand as in De Doncker et al [21]. Measures of implicit and explicit PE were obtained using a line length estimation task and a VAS respectively.…”