Transient autonomic responses during sustained attention in high and low fit young adults
DOI: 10.1038/srep27556
archive: archived pipeline: cataloged verified
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Summary
This study investigates the relationship between aerobic fitness, sustained attention, and autonomic nervous system (ANS) reactivity in young adults. While aerobic fitness is known to support cognitive performance, the physiological mechanisms linking fitness to vigilance capacity remain unclear. The authors hypothesized that ANS reactivity, specifically vagally-mediated heart rate responses, serves as a key mechanism facilitating sustained attention in high-fit individuals. To test this, the researchers compared high-fit and low-fit participants during a prolonged 60-minute Psychomotor Vigilance Task (PVT), measuring both behavioral reaction times (RTs) and event-related heart rate responses. The study included 44 young adults divided into high-fit (≥8 hours of training/week) and low-fit (<2 hours/week) groups, verified via submaximal cardiorespiratory fitness tests. Participants performed the PVT, which required rapid responses to visual targets appearing at random intervals. Continuous electrocardiogram (ECG) data were recorded to analyze Phasic Cardiac Responses (PCRs)—specifically, heart period changes within 1 second of a preparatory cue stimulus. This short-latency window was selected to isolate vagally-mediated parasympathetic activity. The 60-minute task was divided into five 12-minute blocks to assess time-on-task effects. Statistical analyses employed nonparametric permutation tests to evaluate group differences in RTs and PCRs across the task duration. Results indicated that high-fit participants exhibited significantly shorter reaction times than low-fit participants, but only during the first 24 minutes (blocks 1 and 2) of the task. This performance advantage disappeared in subsequent blocks, with high-fit participants actually showing slower RTs than low-fit participants in the final block. Crucially, this behavioral improvement coincided with distinct autonomic patterns: high-fit individuals displayed significant cardiac deceleration (increased heart period) in response to cue stimuli during the first 24 minutes, a pattern absent in the low-fit group. After the 24-minute mark, this decelerative response in high-fit participants also disappeared, aligning with the loss of their behavioral advantage. Baseline measures confirmed that high-fit participants had greater resting vagal tone, evidenced by longer inter-beat intervals and higher root-mean-square successive differences. The findings demonstrate that high aerobic fitness is associated with transient autonomic responses indicative of an enhanced attentive preparatory state, which supports improved vigilance performance. However, this benefit is not sustained indefinitely; both the autonomic reactivity and the behavioral advantage decay after approximately 24 minutes of continuous attention. The study suggests that the superior vagal control in high-fit individuals allows for greater autonomic flexibility and dynamic parasympathetic modulation during early task engagement. These results highlight the importance of considering ANS reactivity when examining the link between fitness and cognition, suggesting that while fitness enhances initial vigilance capacity, the physiological mechanisms supporting this state may be subject to time-on-task limitations.
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| Stage | Outcome | Tool | Model | Prompt | Attempts | Completed |
|---|---|---|---|---|---|---|
| discover | success | Crossref | — | — | 1 | 2026-06-18 |
| archive | success | canonical_url | — | — | 1 | 2026-06-25 |
| extract | success | cached | — | — | 2 | 2026-06-26 |
| clean | success | clean | — | — | 1 | 2026-06-18 |
| chunk | success | chunk | — | — | 1 | 2026-06-18 |
| embed | success | embed | Qwen/Qwen3-Embedding-8B | — | 1 | 2026-06-18 |
| promote | success | — | — | — | 1 | 2026-06-18 |
| summarize | success | llm | qwen3.6-27b-prismaquant | summ-v5 | 1 | 2026-06-26 |
| tag | success | vector_similarity | — | — | 6 | 2026-06-18 |
| verify | success | — | — | — | 1 | 2026-06-26 |
Summary generated by qwen3.6-27b-prismaquant on 2026-06-26; verification: verified.
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- Empirical Findings: physiological data