About HAM.RUN

HAM.RUN is a free, browser-based suite of physiology-grounded models for marathon training and racing. Every calculation runs client-side; nothing about your training is uploaded unless you opt in to cloud sync. The models are derived from peer-reviewed exercise science (Banister fitness-fatigue, Riegel race prediction, Minetti gradient cost, Jeukendrup substrate oxidation, Gabbett ACWR, Scoon heat acclimation, and more) and are intended as educational exploration, not medical prescription.

The 10 calculators cover running economy, marathon periodization, training adaptation, heart-rate pacing and cardiac drift, substrate and time-to-exhaustion modeling, caffeine pharmacokinetics, sauna heat acclimation, race-time prediction, marathon training plan generation, and structured workout generation with Garmin .fit export.

Around them sit elevation profiles and grade-adjusted split tables for 32 marathon courses including all 7 World Marathon Majors, 7 course ranking pages, goal-time pacing tables for every course at 13 finish times from 2:30 to 6:00, 61 concept explainers at /learn, a library of 35 canonical sessions, and 55 glossary definitions. Model provenance — which published model backs each calculator, its validated range, and where it breaks down — is documented at /ai-info.

The same calculation functions are exposed as tools over a public MCP server, so an AI assistant can call the models directly instead of approximating them.