The big race, when it finally arrives, is a test you cannot cram for. We all know this in theory—but in those nerve-wracking final weeks, it’s hard to resist the urge to squeeze in extra miles or faster reps. The problem? If you give in to temptation, you’ll be missing out on some crucial physiological changes that happen only when you balance the stress of regular training with the relative ease of your taper.

Published: Oct 17, 2017 leg muscles actually get measurably bigger and more powerful. A study of Taylor University cross-country runners found that the postworkout response of a gene associated with muscle size quadrupled during the taper period. Other benefits include a boost in oxygen-carrying red blood cells and a reduction in stress hormones, resulting in a 2 to 4 percent improvement in race times.

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To strike the right balance between resting up and maintaining fitness, you have to consider how long you’ll spend tapering and how much you’ll cut your mileage, how often you’ll run, and how hard you’ll work out during that time. Nailing the ideal mix will let you arrive at the starting line ready to take full advantage of all your hard work.

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Running Frequency
Reducing your mileage doesn’t mean spending every other day on the sofa. Aim to maintain roughly the same frequency of runs and hard workouts, but make each of them shorter. For example, if you usually run 10 x 400 at the track, adjust to 8 x 400 two weeks before race day and 6 x 400 in the final week.

Workout Intensity
This is trickier than it sounds, but you should keep the pace of your taper runs—particularly your hard workouts—roughly the same as your training runs. Continuing with intervals, even though you’re doing fewer of them, is crucial to avoid losing fitness during the taper.

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Duration
Runners generally taper for one to three weeks. The “right” length depends on how much you trained: the more fatigue you’ve accumulated, the longer you need to recover. Experiment with different taper durations; when you find yourself bouncing up staircases with a spring in your step a few days before your race, you’ve found the right one.

Volume
A meta-analysis of 27 different tapering studies concluded that the best results come from cutting mileage to 40 to 60 percent of your normal load. The higher your mileage, the more you’ll need to cut. In a multiweek taper, cut your mileage progressively. For example, run 80 percent of your normal mileage in the first week, then 60 percent in the final week.