Figuring Ultramarathon Pace

Typically I run a six-minute mile for a 10K and a seven-minute pace for a marathon. I would like to run a 100K. …

Illustration by Jeremy Duncan

Typically I run a six-minute mile for a 10K and a seven-minute pace for a marathon. I would like to run a 100K. How much do I need to slow down to cover the distance?

—Brian Baker, Boise, ID

Determining a goal pace for an ultra is a common question, especially for runners coming from a road-running background. Since you will be slower on trails, it is not a linear formula. On your long, trail training runs, you can gain a rough idea of your potential race pace by gauging the speed you can maintain comfortably against how you feel using the suggestions below.

Coach Roy Stevenson, who teaches exercise science at Seattle University in Washington, advises gauging ultra pace in three possible ways. One, use a heart-rate monitor in training, then stick to the same heart rate you find you can maintain on long runs in your race, no matter what your pace, the weather or the terrain. Two, learn to rate how you feel at certain paces, using a 1-to-10 scale, then during the event, running at about “4 to 5” will constitute a sustainable, aerobic pace. And three, as physiologist and coach Jack Daniels, PhD., also advises, count steps per inhale and exhale, hitting about a 3-3 count (three steps per each inhale and exhale) for long-distance running.

Practice all three methods in training to get to know the right zone for your race and to figure out which method works best for you. Also, after running even one ultra, you will have a much better idea of what it takes to get across the finish line.