If you compete at longer distances, you've may have heard that 80 percent of your training should be spent running easy and 20 percent should be spent running hard.
This follows the general breakdown of the training miles logged by top distance runners all over the world. While it's common to achieve these percentages by splitting your runs into easy, long, speed and tempo workouts spaced throughout the week, it's also possible to combine them into a single workout and get the benefits of both types of training in one run.
The 80/20 run is a simple training tool you can use to shake up the monotony that's common among most half or full marathon training plans. As the name implies, split your training runs up by time and run the first 80 percent of the run at an easy pace and the last 20 percent at a hard pace.
There's some room for creativity here, since there's a range of speeds that can be considered "easy" or "hard," but generally, aim to keep your easy minutes between 60 to 65 percent of your maximum heart rate and your hard minutes above 80 percent max heart rate. This corresponds to marathon race pace or slower for the easy miles and 10K- or 5K-race pace (or faster) for the hard bit at the end.
More: 3 Rules for Easy Runs
Double The Benefits
The safe, easy miles at the beginning of the workout allow you to hit high training volumes, which have been shown to result in improved distance running performance. By adding the fast miles at the end, you'll be also pushing the limits of your acidosis (lactate) threshold (AT) and aerobic power (VO2max). Since the hard portion of the run is relatively short, it places less stress on your body than does a traditional "hard day" workout, which means you should feel fully recovered for your next run.
You can use the last 20 percent of your run to meet different training goals by varying the speed. Keep the pace steady and comfortably hard to log tempo miles at or just below your AT. Insert short and super fast sprint intervals to improve VO2max and work on your stride rate. Alternatively, run progressively faster over those last few minutes of the run to simulate the grueling finish of a long race and build mental toughness.
Including high-intensity intervals into your workout can also boost excess post-exercise oxygen consumption (EPOC)—the "after-burn" effect that can leave your body burning many more calories for hours after a workout.