Perceived time during exercise is faster in individuals with higher cardiorespiratory fitness and is accompanied by differences in vagal-related autonomic regulation

Exercise provides a powerful model for studying temporal experience under sustained physiological challenge, yet whether cardiorespiratory fitness shapes perceived time during exertion, and whether any such effect is linked to autonomic regulation, remains unclear. The present study tested whether fitness-related effects are most evident in task-embedded measures of temporal experience and progress monitoring versus a decontextualised interval timing probe, with heart rate variability (HRV) indexing vagal-related regulation. Twenty-five adults were grouped as higher fitness (HiFit; n=13; female=6) or lower fitness (LoFit; n=12; female=6) using sex-specific mean cut-points on directly measured VO 2 max and completed 20-min of cycling at 60% VO 2 max while performing a concurrent task designed to standardise attentional focus to external performance cues and minimise variability in attentional strategy. HRV was assessed pre- and post-exercise to index autonomic regulation and provide convergent physiological support for fitness-group differences in vagal-related control. Time perception outcomes comprised passage-of-time estimation (PoT; 0–100), an in-task estimate of temporal progress at 75% of the bout (DTPE; % elapsed), and a 30-s interval production task during cycling (IPT30). HiFit showed higher resting HRV than LoFit (SDNN p = .015; HF power p = .008), while HRV decreased post-exercise in both groups (ps ≤ .002). Task-embedded time perception differed by fitness: HiFit reported faster PoT (p = .029) and provided lower DTPE values at the 75% prompt (p = .027), indicating more calibrated progress monitoring. In contrast, IPT30 did not differ by group (p = .355). Across participants, vagal-related HRV indices tracked PoT and DTPE, but not IPT30. In summary, fitness-related time distortion during exercise was expressed in task-specific temporal experience and progress monitoring rather than generic interval timing and was accompanied by higher vagal-related autonomic regulation. Overall, fitter individuals experienced the same bout as passing faster despite matched relative intensity and standardised attentional focus.