Aid Station Pacing Planner

Most runners build race pacing plans by dividing total distance evenly - which ignores the fact that an uphill kilometre takes far longer than a flat one. This planner uses the ITRA km-effort model to distribute your goal time proportionally by effort, not by distance.

ITRA km-effort for each segment is: distance + gain/100 + loss/150. This formula (published by the International Trail Running Association) captures the energy cost of both ascent and descent. A 5km segment with 500m of gain and 0m of loss has an effort of 10 km — equivalent to running 10km flat. Time is then allocated proportionally to this effort.

Terrain type adjusts the overall scale of effort but distributes uniformly across all segments, so the proportional split remains driven purely by km-effort. Selecting "Technical trail" does not change arrival times relative to each other — it reflects that your goal time already accounts for technical terrain.

Power hike zones are highlighted when a segment pace exceeds 12 min/km (19 min/mi). This threshold, derived from biomechanical research, marks the point at which walking becomes more energy-efficient than running on steep gradients (Minetti et al., 2002). Seeing these zones in your plan helps you anticipate where to hike strategically rather than blowing up trying to run.

How to use this: Enter cumulative D+ and D- from the start for each checkpoint (your GPS file or race website usually lists these). Set a realistic goal time based on the Race Time Predictor. Use the arrival times to brief crew, plan drop bags, and set watch alerts.

ITRA. km-effort formula. International Trail Running Association. itra.run Minetti AE et al. (2002). Energy cost of walking and running at extreme uphill and downhill slopes. J Appl Physiol. 93(3):1039-46.