The Acute Effect of Moderate-Intensity Steady-State Exercise and High-Intensity Interval Exercise in a Mentally Fatigued State on Subjective Ratings of Mental Fatigue

We investigated the effect of 10 min moderate-intensity steady-state exercise (SS) vs. high-intensity interval exercise (HIIE) in a mentally fatigued state on ratings of mental fatigue (MF). Twelve physically active males (age 20.5 ± 0.5 years) completed a 30 min computerized Incongruent Stroop-Word-and-Colour-Test (C-ISWCT) followed by one of the following in a randomized order: A) 5 min light-intensity warm-up, then continuous cycling at 60% maximum heart rate (SS), B) 5 min light-intensity warm-up, then 3 × 20s sprints interspersed with 3 min unloaded cycling (HIIE), C) 15 min rest (CON). Mental fatigue visual analogue scale (VAS) ratings increased statistically significantly pre- to post-MF protocol in all trials (F_1,11 = 114.11, <i>p</i> < .001). Post-warm-up MF ratings were not statistically significantly different between trials but showed a moderately greater reduction in SS vs. CON (d_<i>unb</i> = -0.66) and a large reduction in HIIE vs. CON (d_<i>unb</i> = -0.84). Post-exercise MF ratings were statistically significantly lower in SS and HIIE vs. CON (<i>p</i> = .005, d_<i>unb</i> = -1.52 and <i>p</i> = .006, d_<i>unb</i> = -1.43, respectively). Ten minutes SS exercise and HIIE are similarly effective at attenuating perceptions of MF compared with CON. Short bouts of exercise may combat perceived MF.