Mental fatigue impairs clinician-friendly balance test performance and brain activity

While mental fatigue (MF) increases the probability of losing balance, the underlying neural mechanisms remain to be studied. Balance is commonly represented by technical outcomes difficult to translate to clinical practice. Therefore, the aims of this study were to assess how MF affects clinician-friendly balance tests and if MF interacts with brain activity during these tests. Twelve healthy recreational athletes (age = 23 ± 2 years) participated. MF was induced by a 90-minute Stroop test, while the control task encompassed a time-matched documentary. Two clinician-friendly balance tests (ie, Y-balance test [YBT], reactive balance test [RBT]) were performed before and after the 90-minute tasks. Brain activity was measured using electroencephalography during YBT and RBT. MF significantly decreased RBT accuracy compared to pre-MF and compared to post-control. MF did not affect YBT performance and visuomotor reaction time on the RBT. During the YBT, MF significantly induced higher prefrontal cortex theta activity. Brain activity during the RBT remained unchanged post-MF. MF impairs RBT performance, but no underlying brain activity changes were observed. In contrast, YBT performance did not change due to MF, but alterations in brain activity during YBT performance were in line with previous MF research.