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If your model is on the list, the field will show up in the Connect IQ Store on your phone.

How the plan is worked out — and how it learns from you

1. 1The course: the GPX gives the gradient of every stretch. Each stretch gets a “cost” — how much effort it takes against the flat: steep climbs cost more, gentle descents less, and steep descents slow you again, the more carefully you go down.
2. 2The target: the time you chose is shared out over the stretches by their cost — so every kilometre has its own pace, and they add up to exactly your time. Rests at the checkpoints and technical sections are taken out separately.
3. 3Your answers: the gradient at which you start hiking and how you descend tune the cost of climbs and descents. Your maximum pace shows where the plan asks for more than you can do.
4. 4Your runs: every uploaded recording (“How it went”) is compared with the plan. From all your runs the site works out how much more or less time climbs and descents take you against the flat — and your next plans are worked out with that. Carefully at first (one run counts for half), more with every run. The factors are shown on every plan.
5. 5Everyone together: once there are enough runs from enough people, the model is tuned for everybody too — for anyone with no runs of their own yet. So every uploaded run makes the plans more precise for others as well.
6. 6Course technicality: if runners are slower on the flat and downhill than the gradient explains, the course gets a rating from “Easy terrain” to “Extremely technical” — once there are runs from at least two people. The plan then gives you more time on the most technical sections (at most +50%) without changing your target.

The maths in detail

• A gradient above 8% (or whatever you chose) is planned as a fast hike, not a run. If you run it, you will be ahead of the plan there. The times include the rests planned at the checkpoints.
• Pace by gradient is calculated with Minetti (2002) — the energy cost of running relative to the flat. Climbs follow the curve as published. Descents have their benefit capped: the model on its own claims a steep descent is run at twice flat speed, which does not hold on mountain terrain.
• The plan carries fatigue — the final kilometre is that much slower than the first at the same gradient. It grows with the length of the race and is measured in accumulated effort rather than kilometres. The total does not change: the start gets faster so the end can be slower.

Sources and inspiration

• RunPowerModel — The idea of rating technicality — after RunPowerModel's “Trail Score” (Markus Holler). The maths is our own.
• Minetti et al. (2002) — The energy cost of running and walking on slopes — the curve the pace is worked out from. “Energy cost of walking and running at extreme uphill and downhill slopes”, Journal of Applied Physiology.