Mental Fatigue Effects on the Produced Perception of Effort and Its Impact on Subsequent Physical Performances

The purpose of this study was to investigate the relationship between mental fatigue induced by a demanding cognitive task and impaired physical performance in endurance due to a higher perception of effort. A total of 12 healthy adults and volunteers, who had previously practiced endurance activities for 4 to 8 h per week, performed a one-hour cognitive task involving either the process of response inhibition (Stroop task) or not (visualization of a documentary as control task), then 20 min of pedaling on a cycle ergometer at a constant perception of effort while cardio-respiratory and neuromuscular functions were measured. The Stroop task induces subjective feelings of mental fatigue (vigor: 3.92 ± 2.61; subjective workload: 58.61 ± 14.57) compared to the control task (vigor: 5.67 ± 3.26; p = 0.04; subjective workload: 32.5 ± 10.1; p = 0.005). This fatigue did not act on the produced perceived effort, self-imposed, and did not affect the cardio-respiratory or neuromuscular functions during the subsequent physical task whose type was medium-term endurance. Regardless of the mental condition, the intensity of physical effort is better controlled when the participants in physical activity control their perception of effort. Mental fatigue does not affect subsequent physical performance but estimated perceived exertion, which increases with the intensity and duration of the exercise.