Outside magazine, April 1999
The grounded new way to know how hard to go
By Peter Lewis
You're probably well aware of the fact that you should divide your endurance regimen among long and slow outings, moderate tempo workouts, and speed intervals, but it's harder to know what each of these levels of effort means in concrete terms. For years, sussing this out has required either coughing up for a precise but pricey VO2 max
test or dickering with intricate yet inexact heart-rate calculations. Now, however, there's a third alternative: You can check out the straightforward charts in Daniels' Running Formula (Human Kinetics, $16.95), written by preeminent physiologist and champion-spawning SUNY Cortland coach Jack Daniels. By testing thousands of runners over the years, Daniels was finally
able to pin down a mathematical relationship between effort and speed, which means that if you know how fast you can run, you can figure out how fast you should train. "Your best current race time reflects how fit you are right now ù your aerobic capacity, your running economy, and your mental attitude," Daniels says. Once you know your time (and thus your
speed) for a 5k, 10k, or marathon, simply locate it on the truncated chart to determine what pace you should run for each level of effort. (Daniels believes long, easy runs should be done at 75 percent of your maximum heart rate, tempo runs at 90 percent, and, naturally, intervals at near 100 percent.) The biggest advantage, says Daniels, may be that you won't overdo
it: "Why run faster than you have to run to get the benefits you're trying to reap?"