Source Register
Last reviewed: October 2, 2026
This register tracks the key sources used across Multiday Running. It is not a complete bibliography for every article, but it identifies the main sources behind recurring claims about race formats, records, safety, nutrition, sleep, and gear. Article-level citations should be used for the exact wording and population behind a claim; a source in this register does not validate every statement on the site.
| Claim Area | Primary Source | Confidence / Notes |
|---|---|---|
| Multiday and timed-race formats, records, and championship context | Global Organization of Multi-Day Ultramarathonists | High for GOMU-governed formats and published records |
| 24-hour ultrarunning championship and record context | International Association of Ultrarunners | High for IAU-sanctioned formats and records |
| Backyard ultra rules, yard length, and corral procedure | Big's Backyard Ultra — official rules | High for official backyard format rules; local events may vary |
| Backyard ultra world and national records | Big's Backyard Ultra — record table | High for ratified records; claims the organizers have not ratified are excluded |
| Historical ultramarathon results and rankings | Deutsche Ultramarathon-Vereinigung statistics database | High for results lookup and historical context |
| Exercise-associated hyponatremia guidance | Hew-Butler et al., 2015 consensus statement | High for clinical consensus; not individual medical advice |
| Hyponatremia prevention and field treatment | Wilderness Medical Society guideline, 2019 update (Bennett et al.) | High; graded clinical practice guideline |
| Sex-performance estimates across 50–1,000 km races | Zingg et al., 2014 | Specific to the study's fastest-finisher datasets; not a universal sex gap |
| Participation depth and sex-performance differences in selected ultramarathons | Senefeld et al., 2016 | High for the analyzed races; estimates depend on sample and participation depth |
| Possible long-term effects of repeated ultra-endurance running | Scheer et al., 2022 narrative review | Narrative review; clearest signals are cardiovascular and rare progression after acute kidney injury |
| Gut training and endurance fueling context | Jeukendrup, 2017 | Moderate to high; individual tolerance varies |
| Sleep deprivation in ultra-endurance events | Guilherme et al., 2026 systematic review | Evidence is heterogeneous and predominantly male; race format and individual response vary |
| Ultramarathon fueling, fluid, sodium and caffeine ranges | Tiller et al., 2019 | Position stand; broad planning ranges, individualized in training |
| Energy balance and drinking in a 24-hour race | Costa et al., 2014 | Single 24-hour race, 25 runners; the only direct 24-hour intake study |
| Caffeine doses and side effects | Guest et al., 2021 | High for exercise in general; ultra-specific dosing is extrapolated |
| Injury and illness rates in multiday stage races | Krabak et al., 2011 | High for 7-day, 250 km stage races |
| Paper tape for blister prevention | Lipman et al., 2016 | Randomized trial in four 250 km stage races |
| Recovery after a 161 km ultramarathon | Hoffman et al., 2017 | Western States finishers; longer formats are extrapolated |
| Shoe and gear specifications | Dated manufacturer pages linked from each product guide | High for listed manufacturer facts on the verification date; not independent performance testing |
Corrections
If a source has moved, a record has changed, or a claim needs stronger evidence, email hello@multidayrunning.com with the page URL and suggested source.