The research behind Raceproof

These are the studies behind every readiness rule. When new evidence changes what we recommend, we update the app and this page.

Gut

GutStudy

Carbohydrate intake during the Seville Marathon

Jiménez-Alfageme et al. 2025 · Sports Medicine Open

What it found: Seville Marathon runners averaged 35 g of carbs an hour; only 9% reached the 60 to 90 g/h guideline.
What it means for Raceproof: We check your race fueling against 60 to 90 g/h and help you train toward it.

GutStudy

Carbohydrate dose and late-exercise cycling power

Norte et al. 2026 · Scandinavian Journal of Medicine & Science in Sports

What it found: After 3 hours of cycling, power held up better with 120 g/h of carbs than 60 g/h or water.
What it means for Raceproof: Fueling protects late-race power, so we track carbs per hour in your long sessions.

GutStudy

Gastrointestinal problems and race dropout

Mauvieux et al. 2026 · Nutrients

What it found: Stomach problems during a race were the strongest factor linked to dropping out, and stomach trouble in training predicted it.
What it means for Raceproof: We flag gut problems in training as an early warning.

GutReview

Gut training for endurance athletes

Martinez et al. 2023 · Sports Medicine

What it found: About 2 weeks of practicing carbs during exercise reduced gut discomfort and malabsorption.
What it means for Raceproof: We schedule gut training in the weeks before your race.

GutPosition statement

Nutrition and Athletic Performance

Academy of Nutrition and Dietetics, Dietitians of Canada and ACSM 2016 · Nutrition and Athletic Performance

What it found: For exercise over 2.5 to 3 hours, up to 90 g of carbs an hour.
What it means for Raceproof: We set your carb target from your race length.

Hydration

HydrationStudy

Resting versus exercise sweat sodium

Harris et al. 2026 · Physiological Reports

What it found: A resting sweat test matched exercise sweat sodium best at moderate intensity.
What it means for Raceproof: A sweat test result is enough to set your sodium plan.

HydrationPosition statement

Exercise-associated hyponatremia consensus statement

Hew-Butler et al. 2015 · Clinical Journal of Sport Medicine

What it found: Low blood sodium in races mainly comes from drinking more than you sweat.
What it means for Raceproof: Your fluid plan stays below your sweat losses, never above.

HydrationPosition statement

ACSM position stand: exercise and fluid replacement

Sawka et al. 2007 · Medicine & Science in Sports & Exercise

What it found: Sweat rates vary widely, so plans should be individual; weighing before and after exercise estimates sweat rate.
What it means for Raceproof: Weigh-ins give you a personal sweat rate.

Heat

HeatStudy

Core temperature in a humid half marathon

Sakamoto et al. 2026 · Medicine & Science in Sports & Exercise

What it found: In a humid 27°C half marathon, 19% of recreational runners went above 40°C core temperature.
What it means for Raceproof: We flag heat prep for hot and humid races, even short ones.

HeatStudy

Race-day temperature and marathon finish times

Inoue et al. 2026 · Physiological Reports

What it found: Race-day temperature explained about 11% of the variation in marathon finish times.
What it means for Raceproof: We adjust pacing advice for the race forecast.

HeatStudy

Post-exercise hot water immersion and VO2max

Jenkins et al. 2025 · Journal of Physiology

What it found: 5 weeks of hot baths after training raised VO2max in well-trained runners.
What it means for Raceproof: We include passive heat (hot baths, sauna) as an optional tool, with safety guidance.

HeatStudy

Heat and fueling preparation at Western States

Mougin et al. 2026 · Journal of Science and Medicine in Sport

What it found: At Western States, 90% of runners did heat prep, and all of the fastest finishers had a structured carb plan.
What it means for Raceproof: Hot ultras get both a heat plan and a written fueling plan.

HeatReview

Heat acclimation decay and re-induction

Daanen et al. 2018 · Sports Medicine

What it found: About 2.5% of heat adaptation is lost for every day without heat.
What it means for Raceproof: We time heat work for the final weeks before your race.

HeatPosition statement

Consensus recommendations on training and competing in the heat

Racinais et al. 2015 · British Journal of Sports Medicine

What it found: Heat acclimatization over 1 to 2 weeks is the most important step for hot events.
What it means for Raceproof: Heat counts as Ready after about 10 days of heat work.

Terrain

TerrainStudy

Downhill repeats and muscle damage in trail runners

Martinez-Navarro et al. 2026 · Sports

What it found: Trail runners who did weekly downhill repeats had less muscle damage and kept more leg strength after a long descent.
What it means for Raceproof: We track your descent training against your race's descent.

TerrainReview

Limits to ultramarathon performance

Tiller & Millet 2025 · Sports Medicine

What it found: Muscle damage, often from descending, is the main limit in long ultras.
What it means for Raceproof: Downhill readiness is scored for every hilly ultra.

TerrainReview

Biomechanics and physiology of uphill and downhill running

Vernillo et al. 2017 · Sports Medicine

What it found: Climbing and descending stress the body in different ways.
What it means for Raceproof: We check climbing and descending separately.

Durability

DurabilityStudy

Sex differences in durability after prolonged cycling

Pastorio et al. 2026 · Scandinavian Journal of Medicine & Science in Sports

What it found: After 90 minutes of hard cycling, threshold power dropped 16% in men and 6% in women.
What it means for Raceproof: We judge fitness by how it holds up late, not fresh tests.

DurabilityReview

Physiological durability in endurance exercise

Hunter et al. 2025 · Experimental Physiology

What it found: Durability, how well fitness holds up during long exercise, depends on how long and how hard you've been going.
What it means for Raceproof: We check your long sessions at race effort.

Pacing

PacingStudy

Starting pace and hitting the wall at the Boston Marathon

Dong & Li 2026 · PLOS ONE

What it found: Among 78,912 Boston finishers, starting more than 5% faster than average pace was linked to hitting the wall (26.6% vs 1.5%).
What it means for Raceproof: We help you practice and hold goal pace from the start.

PacingReview

Imposed versus self-paced strategies in endurance events

Ramos-Campo et al. 2026 · Sports Medicine

What it found: No imposed pacing strategy beat self-paced efforts, and long slow starts hurt performance.
What it means for Raceproof: We build your pacing skill with time at goal effort.

PacingReview

Marathon pacing by sex and race

Sha et al. 2024 · Heliyon

What it found: Marathon pacing varies by sex and race.
What it means for Raceproof: We plan pace by course section, not one number.

Taper

TaperStudy

Taper discipline and marathon performance

Smyth & Lawlor 2021 · Frontiers in Sports and Active Living

What it found: Among 158,117 marathoners, strict 3-week tapers were linked to finishes about 2.6% faster than minimal tapers.
What it means for Raceproof: We track whether your taper stays disciplined.

TaperReview

Effects of tapering on performance: a meta-analysis

Bosquet et al. 2007 · Medicine & Science in Sports & Exercise

What it found: The best taper was about 2 weeks, cutting volume 41 to 60% while keeping intensity.
What it means for Raceproof: We check that your taper cuts volume and keeps some intensity.

Raceproof is not medical advice. Talk to your doctor before heat training if you have a heart condition, blood pressure issues, are pregnant, or have had heat illness.