How to pace a hilly race
An even split of the clock is not an even effort when the course goes up and down. Here is a plain method for planning a hilly 10K, half or marathon by effort, with a worked example where every number is computed, not guessed.
Why equal splits feel wrong on hills
Running uphill costs more energy per metre than running on the flat, and running downhill costs less, though not by as much as the climb costs. So if you run every kilometre in the same time, the climbing kilometres are harder than the flat ones and the descending kilometres are easier than they could be. You arrive at the top of a climb having spent more than you planned, and you do not get all of it back on the way down.
The method, in four steps
- Pick the goal time for the whole race from recent racing or a recent hard flat run, as you would for a flat course. The hills do not change the finish time you are aiming for here; they change how you spread it.
- Find the grade of each stretch. Use the course profile from the race website, or a GPX file of the route. Elevation from GPS is noisy, so average it over a couple of hundred metres before trusting any single grade.
- Turn each grade into a pace multiplier. Our hill pace calculator does this for one grade: 5% uphill is about 14% slower per kilometre for the same effort, and a 4% descent is about 5% faster.
- Scale every stretch so the splits add up to your goal time. The slowest kilometres get slower than the average and the downhill ones faster, but the total stays your goal.
A worked example
This is a made-up 10 km course with a total climb of 178 m and a total descent of 196 m (the sample course on the Hillband page), planned for a 50:00 finish. An even split would be 5:00 per kilometre. The hill-adjusted splits below add up to exactly 50:00.
| Km | Even split | Hill-adjusted | Net climb | Difference |
|---|---|---|---|---|
| 1 | 5:00 | 5:02 | 8 m | +2 s |
| 2 | 5:00 | 4:49 | -28 m | -11 s |
| 3 | 5:00 | 4:52 | -9 m | -8 s |
| 4 | 5:00 | 5:23 | 31 m | +23 s |
| 5 | 5:00 | 5:04 | 11 m | +4 s |
| 6 | 5:00 | 4:45 | -33 m | -15 s |
| 7 | 5:00 | 4:50 | -14 m | -10 s |
| 8 | 5:00 | 5:24 | 35 m | +24 s |
| 9 | 5:00 | 5:10 | 17 m | +10 s |
| 10 | 5:00 | 4:41 | -36 m | -19 s |
The slowest kilometre is number 8 at 5:24, and the fastest is number 10 at 4:41: a spread of 43 seconds between the two, on a course with modest hills. Treat the adjusted split as a target for effort, not a pace to hold to the second. The method is an estimate, and heat, wind and how you feel on the day matter more than a few seconds.
Race-day habits that go with it
- Do not try to bank time on the way up or the way down. The plan already gives the climbs their share of the clock.
- On a long climb, watch effort, not the watch. Breathing and perceived effort should match the flat sections. A watch pace that looks slow on a climb is the plan working.
- Use downhills to stay relaxed, not to sprint. Only part of the downhill saving is worth counting on, because braking and tired legs use some of it up.
- Know your steep sections. On very steep sections some runners walk or shorten the stride. The method here is for running; plan walking sections separately.
Print it
If you would rather not do the arithmetic, the free flat band on Hillband prints an even, negative or positive split wrist strip in kilometres or miles. The $5 pass reads your own GPX file in your browser, applies this same method to the whole course, and prints the elevation strip on the band. The file is never uploaded.
Method: running energy cost against grade from Minetti et al., Journal of Applied Physiology 93 (2002); the damping choices (square root, grade limits, half of the downhill saving) are ours. Not coaching or medical advice.