80/20 Running: Run Stronger and Race Faster by Training Slower

by Matt Fitzgerald

Running too hard too often is the single most common and detrimental mistake in the sport.

Seiler’s rule also helps runners by explicitly defining low intensity. The boundary between low intensity and moderate intensity, according to Seiler, falls at the ventilatory threshold, which is the intensity level at which the breathing rate abruptly deepens. This threshold is slightly below the more familiar lactate threshold, which you can think of as the highest running intensity at which you can talk comfortably. In well-trained runners, the ventilatory threshold typically falls between 77 percent and 79 percent of maximum heart

Heart rate monitoring in particular is an effective tool for getting runners to slow down, while pace targets are better for getting runners to push themselves in the 20 percent of their workouts when they’re supposed to.

The ultimate mark of skillful running is the ability to run with minimal mental effort.

The three most practical measures of running intensity are perceived effort, heart rate, and pace.

I suggest you use perceived effort to establish the appropriate intensity at the start of a workout or workout segment. Then rely on pace or heart rate to maintain that intensity while allowing your perceived effort to gradually increase as fatigue sets in.

One alternative is a thirty-minute time trial. Here’s how it works: Warm up with several minutes of easy jogging and then run as far as you can in thirty minutes while wearing your heart rate monitor. Your average heart rate during the last ten minutes of this effort is your lactate threshold heart rate. The downside of this test is that it’s rather painful.

When you compete, your pace determines your finish time, and your finish time is the basis for assessing your performance. Heart rates are not included in official race results. No awards are given for the greatest perceived effort.

Start by doing either a thirty-minute time trial, a perceived effort–based test workout, or a talk-test workout to determine your lactate threshold heart rate, then calculate your five heart rate training zones using the percentages in Table 6.1. Use one of these same workouts to calibrate your perceived effort ratings, anchoring your lactate threshold intensity to a perceived effort of 6 on a 1 to 10 scale. Determine target pace ranges that correspond to your five heart rate zones either by finding the pace that corresponds with the heart rate marking the low end and high end of each zone or by using the McMillan calculator. Use perceived effort to establish your initial intensity whenever a workout calls for a change in intensity. Use heart rate as your primary intensity metric in all low-intensity runs (Zones 1 and 2). Use both heart rate and pace to regulate intensity when running at moderate intensity (Zone 3).

Use pace as your primary intensity metric when running at high intensity (Zones 4 and 5), except when running uphill, in which case you should rely on perceived effort. Use perceived effort to fine-tune your intensity during your most challenging workouts. Specifically, use it to ensure you finish all such runs feeling you could have run at least a little faster or farther. Use perceived effort to adjust your intensity on “flat” days. Specifically, when you feel worse than normal at a given target heart rate or pace, slow down.

“Do approximately 80 percent of your training at low intensity and 20 percent at moderate and high intensities, except during specific periods of training when it is beneficial to do somewhat more or somewhat less low-intensity training, and unless you learn through experience that you benefit from slightly greater or slightly lesser amounts of low-intensity running, and be sure to vary the balance of moderate- and high-intensity training in your program based on the sort of race you’re preparing for.”

The human body is not able to absorb increasing training loads for longer than about twenty-four weeks at a stretch.