Mental fatigue accompanied by whole-body surface cooling is associated with the impairment of subsequent endurance exercise performance.

PURPOSE: To investigate whether mental fatigue induced by psychological tasks during whole-body surface cooling influences subsequent endurance exercise performance and whether subjective fatigue is associated with performance variability and neuroendocrine responses.

METHODS

Nine young adults participated in two trials: a mental stress (MS) trial involving the Stroop test (500 stimuli/set × 2) and a control (CON) trial involving watching a video. Both were conducted during whole-body surface cooling using a water-perfused suit (10 °C, 10 min, then 15 °C, 85 min). The time to exhaustion (TE) during cycling at 80% peak oxygen uptake was evaluated. Chalder's fatigue score (CFS), plasma adrenaline ([Ad]p), noradrenaline ([Norad]p), and cortisol ([Corti]p) concentrations were measured before and after intervention and exercise.

RESULTS

After the intervention, the CFS increased in the MS trial, but not in the CON trial. [Ad]p and [Norad]p remained unchanged after the intervention and increased after exercise in both trials, and an increase with exercise was prominent in the MS trial. [Corti]p remained unchanged. TE decreased by 5.7% in the MS trial. However, this was not statistically significant. The difference (Δ) in TE between trials was significantly negatively correlated with ΔCFS (r = - 0.919, P = 0.002). ΔCFS was significantly positively correlated with Δ[Norad]p (r = 0.795, P = 0.010), while not with [Ad]p or [Corti]p.

CONCLUSION

Mental fatigue accompanied by whole-body surface cooling variably influences subsequent endurance exercise performance with decrements associated with greater subjective fatigue and heightened sympathoadrenal-medullary activity though trial-level effects were not significant. There was no apparent hypothalamic-pituitary-adrenal axis involvement.