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

by Matt Fitzgerald

Arthur Lydiard had it right in 1962. If you want a better stride, all you have to do is run enough so that eventually you can run for two or three hours without looking any less fresh at the end than you did at the beginning and your form will “take care of itself.” Running at low intensity most of the time (specifically, 80 percent of the t...

When you’re working very hard in the middle of a run, you can sense it even if your windpipe is not burning and there is no pain in your calf muscles. In fact, numbing the legs with anesthesia has no effect on perceived effort. The reason is that perceived effort is literally “all in your head.” Studies have demonstrated that effort perception is mainly a function of how hard the brain is working to drive the muscles. In other words, it is the brain’s perception of its own effort, not the body’s. The harder the brain is driving the muscles, the more intense the effort feels.

If you start running at a full sprint, you will experience a high level of effort immediately, before you get tired. That’s because your brain has to drive your muscles very hard when you run fast. On the other hand, when you run slowly, your sense of effort is low initially, but then it increases gradually as you keep going. That’s because your brain has to work harder and harder to drive the muscles as they become fatigued. What’s more, as we saw in the preceding chapter, the brain itself becomes fatigued during prolonged low-intensity exercise so that actual stimulation of the muscles by the brain decreases even though the brain is trying harder to keep the body moving.

What all of this means to you is that the relationship between perceived effort and intensity is not a pure one, but is corrupted by fatigue. The effect of fatigue on perceived effort has important practical implications for the use of this metric to monitor and control running intensity. If you do a long run at a steady pace, your intensity, by definition, will also remain steady, but your perceived effort will increase as fatigue sets in. To keep your effort steady, you will have to slow down somewhat toward the end of the run. This is not the most sensible way to use perceived effort to control running intensity, however. Instead, 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.

This is not to say that you should ever completely ignore perceived effort when running. On the contrary, you must always allow perceived effort to have the final ...

Even though perceived effort is “all in your head,” it tells you how your body is doing in a holistic way that pace and heart rate do not. Any factor that affects your body’s capacity in a given moment will alter the relationship between m...

Every runner has occasional flat days in training. Often these days come when you least expect them and have no apparent cause. But there’s always a cause, whether it’s identifiable or not, and this feeling of flatness is your brain’s way of telling you that it has detected something amiss internally and you shouldn’t push yourself. On these days, you will experience unusually high effort at any given pace or heart rate. If you force yourself to stick to a preselected pace or heart rate target, you will probably end up feeling even worse the next day. In such circumstances, it’s best to trust your brain more than you trust your GPS watch or your heart rate monitor and slow down as much as necessary to keep your perceived effort where it should be.

There are several factors that shape each runner’s personal “heart rate profile.” The most important factors are body size (larger individuals typically have lower resting heart rates), age (maximum heart rate tends to decline with age), aerobic fitness (fitter individuals are able to sustain higher heart rates for longer periods of time), and heredity (a number of genes influence resting heart rate, maximum heart rate, and innate aerobic fitness).

Exercise scientists determine the lactate threshold heart rate of individual runners by having them run at incrementally increasing speeds on a treadmill until the blood lactate concentration is 4 mmol/L. The heart rate at this point is by definition the runner’s current lactate threshold heart rate. It’s not quite as precise as it sounds, though. A runner who goes through this test five days in a row might get a slightly different result each time, because the body’s physiological state changes from day to day.

Science has shown that runners get equally fit whether they exercise slightly above, precisely at, or slightly below the heart rate that is associated with a blood lactate concentration of 4 mmol/L in their designated moderate-intensity workouts. In other words, close is good enough when it comes to determining the lactate threshold heart rate, and it so happens that it’s possible to get close to the scientific standard for identifying the lactate threshold with do-it-yourself alternatives to lab-based testing.

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.

A less taxing option is to determine your lactate threshold heart rate by perceived effort. As I mentioned in the previous section, the lactate threshold heart rate corresponds to a rating of 6 on a 1 to 10 scale of perceived effort. So you can estimate your lactate threshold heart rate by starting a run at a perceived effort of 1 and then increasing your effort point by point until you give it a rating of 6. Your heart rate at this point is your lactate threshold hea...

Another simple do-it-yourself method of determining the lactate threshold heart rate is the talk test. The lactate threshold heart rate is associated with the fastest running pace at which a runner is able to talk comfortably. While wearing a heart rate monitor, start jogging at a slow, steady pace. After one minute, recite the Pledge of Allegiance (see Figure 6.3) and note your heart rate. Alternatively, count upward from 120 to 125. Now increase your speed slightly, wait a minute, recite the Pledge (or count) again, and again note your heart rate. Continue in this fashion until talking is slightly uncomfortable. Note your pace at the previous speed when speaking was comfortable or sort of comfortable. Your heart rate at that pace is your current lactate threshold heart rate. Comfortable in this context does not mean that you are able to talk without feeling any sense of dyspnea, or oxygen deficit, but the feeling should be quite mild. Here’s a good rule of thumb: If your breathing returns to its pretalking rhythm by the third breath after you finish speaking, then you were able to talk comfortably. Note that the smaller your speed increases are when you perform this test, the more precise the result will be.

It’s easy to line up my five-zone heart rate system and the scientists’ three-level hierarchy, as we’ve done already with respect to perceived effort ratings. Remember that I’ve chosen to define low intensity as the range of intensities that fall below the ventilatory threshold, moderate intensity as the range of intensities between the ventilatory threshold and the lactate threshold, and high intensity as anything above the lactate threshold. The ventilatory threshold falls at the bottom end of Zone 3 (or 96 percent of lactate threshold heart rate). The lactate threshold is aligned with the top end of Zone 3 (or 100 percent of lactate threshold heart rate). That’s your moderate intensity range. Zones 1 and 2, then, represent low intensity and zones 4 and 5 are high intensity.

Each zone has its proper place in a runner’s training. Zone 1 is appropriate for warm-ups, cool-downs, recovery periods between high-intensity intervals, and recovery runs. Zone 2 is targeted in what I call foundation runs (which most other coaches call easy runs) and long runs. Zone 3 is targeted in tempo runs, cruise intervals, and fast finish runs. A typical threshold run comprises a steady effort of fifteen to forty minutes in Zone 3 sandwiched between a warm-up and a cool-down. Cruise intervals are like tempo runs except the middle of the sandwich is separated into multiple shorter Zone 3 efforts. A fast finish run is a foundation run with a short (five to fifteen minutes) effort in Zone 3 tacked onto the end. Zone 4 is typically targeted in high-intensity interval workouts featuring longer intervals (two to eight minutes) and in fartlek (or what I call “speed-play”) runs, which are simply interval workouts with a less formal structure that are done on roads or trails instead of at the track. Zone 5 is appropriate for high-intensity runs featuring shorter intervals (thirty to ninety seconds), hill repetition runs, and more intense speed-play runs.

Heart rate monitoring is especially useful in low-intensity runs. The reason is that, unlike pace, heart rate is not a performance metric. Runners don’t instinctively push to achieve higher heart rates that they can boast about the way they often push to achieve faster split times. When runners are given a heart rate “ceiling” to stay below, they usually have no trouble respecting it. But when they are given a pace target, they often try to beat it.

Heart rate monitoring is less useful in high-intensity runs. The reason has to do with a phenomenon called cardiac lag. When you speed up during a run, your heart will respond by increasing its contraction rate until it is sufficient to supply your muscles with the extra oxygen they’re now asking for. This process is not instantaneous. Depending on how much your pace increases, it may take your heart thirty seconds or more to settle into a new rhythm.

Cardiac lag has important implications for heart rate monitoring during workouts that include changes in pace. For example, suppose you are doing a run that features six intervals of thirty seconds in Zone 5 with two-minute recoveries in Zone 1 between intervals. When you start the first interval, you will accelerate abruptly, and your heart rate will begin to climb. But chances are your heart rate will not actually reach Zone 5 until the very end of the thirty-second interval, if even then. That doesn’t mean you failed to do the interval at the right intensity. As long as you were running fast enough that your heart rate would have reached Zone 5 if you had continued at that pace, then you did it correctly. Likewise, when you slow down for recovery at the end of your first thirty-second Zone 5 interval, your heart rate will begin to decrease. But because of cardiac lag, no matter how much you slow down, your heart rate might not get all the way back down to Zone 1 before your two-minute recovery ends and it’s time to start the next interval. Again, this doesn’t mean you screwed up. As long as you jogged slowly enough that your heart rate would have dropped down to Zone 1 eventually, you did it correctly.