A 5:00 kilometer up an 8.4% grade costs about as much as a 3:15 kilometer on the flat. Trailbuddy shows you both, so a hilly run reads as the effort it was.
±45%
Grades the research measured, and the range Trailbuddy uses
10%
Downhill grade past which the live screen shows descent rate
4
Places you see GAP: live, the run, each lap, each climb
Trailbuddy prices the grade with published research
Minetti and colleagues measured the energy cost of running on treadmill grades from 45% downhill to 45% uphill. Level running costs about 3.6 joules per kilogram per meter; the steepest climbs cost more than five times as much. Trailbuddy divides your pace by that cost ratio for the grade you ran, so the grade-adjusted pace is the flat pace that would have cost the same.
Trailbuddy stays within the grades the study measured and never extrapolates beyond them.
Trailbuddy shows your descent rate on steep downhills
On a gentle descent gravity helps and the formula gives you a slower flat-ground pace. Past 10% downhill your speed depends on footwork, braking and nerve more than on energy. When the last 30 seconds of a run average steeper than that, the live screen shows your descent rate in meters per hour instead of a grade-adjusted pace. The grade-adjusted pace of the run, each lap and each climb still prices every stretch with the curve, steep descents included.
A running tracker
Pace 5:00 /km
Your watch files the water tower climb as your slowest kilometer of the week.
Trailbuddy
Grade-adjusted pace 3:15 /km
Trailbuddy shows the flat-ground pace that would have cost the same effort, next to the pace you ran.
The grade is the one thing Trailbuddy adjusts for
Mud, roots, heat and tired legs cost time too, and no formula prices them well. Trailbuddy records the trail surface and the weather with every run and shows them next to the time, and leaves the time as you ran it.
The same curve applies to every runner. Uphill economy differs from person to person, so read GAP as a way to compare hilly and flat runs, and your own history on the same climb as the measure of progress.