Why a short loop?
24-hour runs are usually staged on short loop courses — typical loop lengths range between 800 m and 2,000 m. At the Grimming360 in Irdning the precise running loop was around 1,080.70 m. Three reasons argue for this short format:
- The course can be served centrally with the aid station, medical tent and camp area — runners pass them every few minutes.
- The residual-distance measurement after the 24 hours stays manageable: runners stop exactly where they are, and the residual metres are taken on the spot.
- Spectators and helpers can follow the entire race without moving — and that builds the atmosphere these events are known for.
AIMS measurement
For results to count toward official rankings (such as the Austrian ultra cup or world and European championships), a 24-hour course must be measured to AIMS standard (Association of International Marathons and Distance Races). A certified measurer surveys the loop with a calibrated Jones counter; the result is logged in the official race documentation.
At the Grimming360 the running loop was re-measured before each edition — a routine step, since temporary course markings can shift slightly from year to year.
Elevation profile and surface
24-hour courses generally have very small elevation differences — classic examples like Irdning sit at around 2 metres per loop. This is not a coincidence: over 24 hours of running, even small elevation changes add up to thousands of metres, and a flat course keeps the load even. The surface is typically a mix of asphalt, compacted gravel and meadow with good drainage — the last matters when a summer event runs into a thunderstorm.
Running and cycling on separate lanes
Some events run a parallel cycling loop alongside the running course. At the Grimming360 this measured around 3,300 m, with a meadow section, a short climb into the village and a small downhill on asphalt. The shared finish area is lane-separated — an important safety measure at longer events.
Lighting and night-time safety
Because a 24-hour run typically starts at 12:00 or 19:00, every participant runs through at least one full night. Organisers ensure lighting along the loop — usually a mix of fixed floodlights at critical points (turning points, road crossings) and a continuous light chain along the main stretch. Reflective vests are recommended or required at night, depending on the event.
How runners train for the night-to-day transition is on the training page. Aid-station and nutrition concepts are on the nutrition page.