Sleep in hybrid (HYROX) athletes
Resistance vs endurance session before bed changes sleep latency, WASO and cardiac arousals (pilot, n=8)
Participants & Protocol
n=8 male Hyrox athletes (23-32 years), experienced hybrid athletes
Protocol
Design: observational within-subject comparison of nights after a primarily resistance vs a primarily endurance training bout (from the abstract)
A validated, non-invasive ambulatory sleep monitor after a primarily resistance OR endurance training bout, within a two-week period: two resistance and two endurance post-training nights per athlete
Outcomes: total sleep time (TST), sleep onset latency (SOL), wake after sleep onset (WASO), sleep-stage proportions, number and duration of cardiac arousals before and after sleep onset
Ecologically valid design (home setting, not a laboratory)
Key Findings
Despite self-reported "good" sleep quality, TST was short (~6.6 h) and REM ~5% lower than reference non-athletes — in line with other sport populations
After resistance vs endurance training: longer sleep onset latency (29 vs 10 min, p=0.003) but shorter WASO (31 vs 48 min, p=0.008)
Cardiac arousals matched: more before sleep onset after resistance training (13 vs 5 events, p=0.006), fewer after sleep onset (81 vs 99 events, p=0.010)
Sleep latency and WASO were positively associated with cardiac autonomic responses before and after sleep onset
Practical Application
In 8 experienced male Hyrox athletes, a resistance session before bed meant a longer time to fall asleep (29 vs 10 min) but less wake after sleep onset (31 vs 48 min) than an endurance session, with cardiac arousals shifted the same way; total sleep was ~6.6 h with ~5% less REM than non-athlete references. Session type changes the shape of the night, not obviously its total.
Hybrid/HYROX athlete: track sleep by the type of hard session — a late strength session may delay falling asleep; a late endurance session may fragment the night more
Inference, not tested: ~6.6 h TST in athletes who rate their sleep "good" is the more actionable number — sleep duration, not architecture, is the first lever
Use as a hypothesis for your own n=1 tracking, not as a hard rule (n=8 pilot)
Limitations
n=8, men only, 23-32 years, pilot design; two nights per condition
Ambulatory monitor (not polysomnography) — limited accuracy of sleep architecture
"Primarily resistance/endurance" sessions, not a standardised HYROX load; session timing relative to bedtime not given in the abstract
Short window (2 weeks), no long-term tracking
How this entry was checked and changed
Why this level
regraded 2026-09-27 from C: small within-subject observational cohort, n=8 (rubric: small cohort / correlational = B); treat as preliminary
Content correction 2026-09-27
Key Findings "the direction of the session-type → sleep effect was examined but is not firmly established" -> the abstract reports the results: SOL 29 vs 10 min (p=0.003), WASO 31 vs 48 min (p=0.008), cardiac arousals 13 vs 5 and 81 vs 99, TST ~6.6 h, REM ~5% below reference. Added; lead bullet now carries them.
Level C -> B per KB-LEVEL-RUBRIC (small within-subject observational cohort); the snapshot's "C" is below the rubric for this design. Sport "strength, hybrid" -> "strength, general".
2026-09-28: added Protocol from the abstract (Europe PMC/PubMed PMID 41762273).