ArticleFrontiers in physiology2026
Sleep-timing irregularity moderates the within-participant association between training load and next-morning heart rate variability in university sport participants: a 28-day study.
Article in Frontiers in physiology, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
What it found
Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.
The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
0 citing papers in PubMed.
No citing paper in PubMed yet.
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
2 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
Background: Heart rate variability (HRV) describes beat-to-beat variation in cardiac intervals; the root mean square of successive differences (RMSSD) is a time-domain index of short-term cardiac vagal modulation. We examined whether nightly deviation from habitual sleep midpoint moderated the association between prior-day internal training load and next-morning natural-log-transformed RMSSD (lnRMSSD), and whether analogous interactions were present for resting heart rate, wellness strain, and countermovement-jump (CMJ) height. Methods: University students engaged in regular sport training completed 28 days of habitual monitoring. Internal load was session duration multiplied by session rating of perceived exertion. Wrist actigraphy and sleep diaries estimated sleep midpoint, and 5-min morning RR recordings yielded lnRMSSD. Mixed models separated within- and between-participant components and tested within-participant load (per 100 arbitrary units [AU]) × absolute midpoint deviation (per 30 min). Results: The analysis included 1,232 mornings from 54 participants (57.4% female; age 21.0 ± 1.7 years). At each participant's mean midpoint deviation, greater-than-usual load was associated with lower next-morning lnRMSSD (β = -0.0089, 95% CI -0.0127 to -0.0051; p < 0.001). At mean load, greater-than-usual midpoint deviation was also associated with lower lnRMSSD (β = -0.0156, 95% CI -0.0268 to -0.0045; p = 0.006). The interaction was negative (β = -0.0101, 95% CI -0.0153 to -0.0048; p < 0.001). Thus, the inverse within-participant association between load and lnRMSSD strengthened as sleep-timing irregularity increased. No load-by-midpoint interaction was detected for resting heart rate, wellness strain, or CMJ height after false discovery rate adjustment. The primary interaction persisted after adjustment for prior-morning lnRMSSD (β = -0.0096, 95% CI -0.0147 to -0.0046; p < 0.001). Conclusion: The within-participant association between training load and next-morning cardiac vagal modulation was moderated by sleep-timing irregularity. These field-based associations do not establish a sleep mechanism, causal recovery effect, or decision threshold.
Indexed as
Identifiers
What OpenQuestion holds
Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.