Adaptive cognitive tasks for mental fatigue: An innovative paradigm for cognitive loading in human performance.

Mental fatigue (MF) can impair cognitive and physical performance in sport. We tested the hypothesis that a shorter adaptive Time Load Dual Back (TLDB) task induces MF faster than a longer Stroop; and subsequently impairs cognitive and intermittent running performance. This study employed a randomized within-participant design. 25 trained individuals performed a Yo-Yo test after one of four experimental conditions (30-min Stroop, 20-min and 10-min TLDB tasks, and active control). Cognitive performance was assessed using the Psychomotor Vigilance Task (PVT) before and after the experimental conditions. Measures of mood, workload, MF, RPE, heart rate (HR), heart rate variability (HRV) and blood lactate were collected. ANOVAs determined the effect of the 4 conditions. Stroop and 20-min TLDB conditions impaired running performance similarly (p =.015), while no differences are reported for 10-min TLDB and Control. No significant differences in physiological parameters were reported during the Yo-Yo test although RPE was significantly higher in the Stroop and 20-min TLDB conditions (p =.014). Stroop and both TLDBs conditions impaired PVT's cognitive performance (p =.029), MF (p =.012), mental demand (p <.001), HR (p =.021) and HRV (p =.033); with 20-min TLDB task having the higher significant impact. Mood alterations were similar between Stroop and TLDB conditions. Intermittent running (Yo-Yo) and cognitive (PVT) performances, and subjective ratings were impaired by 30-min Stroop and 20-min TLDB tasks; while 10-min TLDB did not to impair performance. Shorter adaptive modes seem to be more effective in inducing MF and could have relevant clinical applications to assess conditions such as traumatic brain injury and concussion. [ABSTRACT FROM AUTHOR]