Practical implications

Introduction

Materials and methods

Results

Discussion

Conclusions

Acknowledgements

References

Objectives The aim of this study was to investigate whether 4 weeks of endurance training could improve tolerance to mental exertion in untrained participants. Design Longitudinal training study. Method Twenty untrained young adults (14 F, 6 M; 27.6 ± ۶٫۲ years) completed a 4-week training protocol in a randomised and counterbalanced order. Baseline and follow-up assessment were conducted over three sessions in the week preceding and following the training period. During session 1, participants completed an incremental maximal ramp test. During sessions 2 and 3 participants completed a 15 min cycling time trial preceded by either a mental exertion or control conditions. Following baseline assessments, participants were randomised into a physical training or placebo group that completed the training intervention thrice weekly over four weeks. Results The physical training resulted in increases in VO2peak relative to the placebo group (p = 0.003). Linear mixed models utilising the control condition time trial performance as a covariate found the physical training group increased their time trial distance following the mental exertion condition to a greater extent than the placebo group (p = 0.03). RPE during the time trial and perceptual measures of mental exertion did not significantly change between groups (all p > 0.10) although interaction effects were observed when considering the RPE-power output relationship during the time trial. Conclusions Four weeks of endurance training increased tolerance to mental exertion in untrained participants during a subsequent physical performance, but not during prolonged cognitive performance. This finding suggests that the ability to tolerate mental exertion is trainable in at least some contexts and highlights the far-reaching benefits of endurance training.

Introduction

Endurance exercise training results in adaptations to the neuromuscular, metabolic, cardiovascular, respiratory and endocrine systems as reflected in improvements in key parameters of aerobic fitness, exercise economy and lactate/ventilatory threshold 1. Aside from these traditional, peripherally-based adaptations, endurance exercise is linked to cognitive benefits 2,3 as well as structural 4 and functional changes in the brain 5. These observations appear consistent with adaptations that, among other benefits, would confer improved efficiency and/or capacity for mental work. Brain adaptations to physical training could therefore also be important in our resistance to mental fatigue. Acute mental fatigue is defined as a psychobiological state that may arise during or after prolonged cognitive activities; it is characterized by feelings of tiredness or exhaustion, and a decreased commitment and increased aversion to continue the current activity 6. Acute mental fatigue has an adverse effect on cognitive function 7,8 and endurance performance 9. Mental fatigue appears to impair endurance performance through an increased perception of effort during subsequent physical exercise. However, a physiological reason for an increase in perceived exertion has, to date, only been postulated 10 . Beyond the physiological mechanism of mental fatigue, it is important to understand whether the ability to resist mental fatigue is associated with a genetic predisposition or displays a trainable phenotype.