ABSTRACT:
Intense cognitive‐motor dual‐tasks (CMDTs) typically induce central nervous system fatigue and reduce cognitive performance, even in individuals with high fitness levels. We aimed to explore the efficiency of CMDT training in preventing central fatigue and cognitive performance decline in such scenarios. Forty trained adults were randomly assigned to one of three high‐intensity interval training (HIIT) groups (4 weeks, 2 sessions/week): cycling alone (HIIT
CTRL
), cycling with cognitive training during low (HIIT
DTL
), or high‐intensity intervals (HIIT
DTH
). Each training session consisted of 4 × 6 min self‐selected intervals based on perceived effort (3 min “very strong”, 3 min “very low”). Before and after training, participants completed an incremental cycling cognitive test (ICCT) until reaching task failure (TF). Sustained attention Mackworth score, knee‐extensor neuromuscular peripheral (e.g., peak twitch) and central (voluntary activation, VA) indices, prefrontal cortex (PFC) oxygenation, cycling and mental perceived efforts were assessed at each stage. Data were interpolated at 20%–40%–60%–80% relative to TF pretraining (TF
PRE
). All groups increased ICCT endurance time after training (+3.0 ± 4.2 min,
p
< 0.001). After training, the Mackworth score increased at rest, 80% and TF
PRE
(+11% ± 2%,
p
< 0.001), alongside similar PFC oxygenation patterns (
p
= 0.13), whatever the group. HIIT
DTL
and HIIT
DTH
mitigated VA decline at TF
PRE
(+4.5% ± 3.6% and +5.0% ± 3.7%, respectively,
p
< 0.001) compared to HIIT
CTRL
(+0.9% ± 4.0%). HIIT
DTL
and HIIT
DTH
reduced mental effort after training throughout the ICCT (−14 ± 11 and −19 ± 12,
p
≤ 0.002) compared to HIIT
CTRL
(−6 ± 13). Whereas a traditional HIIT program was associated with improvements in sustained attention alongside gains in endurance performance, CMDT‐specific training more effectively mitigated central fatigue and reduced perceived mental effort during challenging CMDT scenarios.