Fig 1.
Schematic representation of the experimental design.
Participants completed three separate conditions. Two involved the performance of an intermittent handgrip (HG) task until ratings of fatigue (RoF) were perceived as moderate (MOD; RoF = 5) and severe (SEV; RoF = 8), representing the experimental manipulation, while the other was a control task (CON) in which no prior exercise was performed. Endurance performance was assessed during a sustained, sub-maximal isometric contraction of the dominant knee extensors (KE), with perceptual (i.e. effort) and affective responses to the task recorded throughout. RoF: Ratings of fatigue; DASS: Depression, Anxiety and Stress scale; KSS: Karolinska Sleepiness Scale; MVC: Maximal voluntary contraction.
Table 1.
RoF at the beginning of each session and the physical and perceptual responses to the HG task performed in the experimental manipulations.
Fig 2.
The effect of the subjective intensity of the pre-induced state of fatigue on endurance performance.
Knee extensor endurance performance presented for the control (CON; blue), moderate RoF (MOD; purple) and severe RoF conditions (SEV; red). Lines and error bars indicate condition means and standard deviations, respectively. *: Time to task failure (TTF) significantly different in MOD and SEV compared to CON (p<0.01).
Fig 3.
Effect of the experimental conditions on perceived fatigue.
Rating of Fatigue (RoF) reported both during and post the knee extensor (KE) endurance task is presented for the control (CON; blue), moderate RoF (MOD; purple) and severe RoF conditions (SEV; red). Circles represent individual ratings in each condition. Lines and error bars indicate condition means and standard deviations, respectively. Dashed guidelines represent the target RoF prior to the start of the endurance task in each condition. *: RoF significantly different in MOD and SEV compared to CON (p<0.01).
Fig 4.
Effect of experimental conditions on perceived effort during the endurance task.
Profile of subjective perceived effort responses across the knee extensor (KE) endurance task within the control (CON; blue), moderate RoF (MOD; purple) and severe RoF conditions (SEV; red). Individual responses across time are displayed by smoothed thin lines within each condition. Thick lines represent the change in mean scores over time in each condition, with grey boarders representing 95% confidence intervals.
Fig 5.
Effect of experimental conditions on affective valence during the endurance task.
Profile of reported affective valence across the knee extensor (KE) endurance task within the control (CON; blue), moderate RoF (MOD; purple) and severe RoF conditions (SEV; red). Individual responses across time are displayed by smoothed thin lines within each condition. Thick lines represent the change in mean scores over time in each condition, with grey boarders representing 95% confidence intervals.
Table 2.
Moderating effect of the dimensions of interoception on the relationship between perceived fatigue and effort.
Table 3.
Moderating effect of the dimensions of interoception on the relationship between perceived fatigue and the affective valence.