The taper is the part of a training block that most runners get wrong in one of two directions. Some barely reduce at all, arrive on the start line carrying three months of fatigue, and run below their fitness. Others cut everything for three weeks, lose their sharpness, and feel flat by halfway.
The research on this is unusually clear, and it points to a middle path: cut the volume hard, keep the intensity, and do it for a length of time that depends on the race. Here is why that works, in one picture.
Fitness fades slowly. Fatigue fades fast.
Cut volume for the final three weeks and fitness gives up only a little, while the fatigue you built with it falls by more than half. The gap that opens between them is the freshness you race on.
- Fitness
- Fatigue
- Freshness
Modelled, not measured: fitness and fatigue are each shown as a percentage of where they stood at the start of the taper, using a standard impulse-response model with fitness decaying over about six weeks and fatigue over about one. The exact numbers are individual; the shape is not.
What a taper actually does
Training leaves two things behind: fitness and fatigue. Both build together, which is why a hard block feels hard even as you get faster. The difference is how quickly they fade. Fitness is stable, with a half-life measured in weeks. Fatigue clears in days.
A taper exploits that gap. Reduce training for the final weeks and fitness gives up only a little, while fatigue drops away. The freshness that opens up between them is what lets you run at the fitness you actually built, rather than the fitness minus the tiredness.
The best-known review of the evidence, a meta-analysis by Bosquet and colleagues covering 27 studies, found that the most effective tapers cut training volume by 41 to 60 percent over about two weeks, kept intensity and session frequency largely unchanged, and improved race performance by around 3 percent on average. Three percent of a four-hour marathon is about seven minutes. No session you could add in those two weeks is worth that.
How long, by distance
The right taper length scales with how much fatigue the block accumulated, which mostly tracks the distance you trained for.
| Race | Taper length | Volume in race week |
|---|---|---|
| 5K | 7 to 10 days | about 50 to 60 percent of normal |
| 10K | 10 days | about 50 percent |
| Half marathon | 10 to 14 days | about 40 to 50 percent |
| Marathon | 14 to 21 days | about 40 percent |
The marathon sits at the long end because the peak weeks of a marathon block leave more fatigue to shed, and because the race itself is long enough that arriving slightly under- recovered costs a lot. A 5K needs little more than a sharp final week. The guides for each distance cover where the taper sits in the whole block: marathon, half marathon, 10K, and 5K.
What to cut and what to keep
The mistake that turns a taper into detraining is cutting the wrong things. The evidence supports a clear split.
Cut volume. This is where almost all of the reduction comes from. Shorten the long run first and most, then trim the easy days. By race week a marathon runner is doing a long run of 8 to 10 miles at most, and easy runs of 3 to 5 miles.
Keep frequency. Run roughly as many days as you normally do, just shorter. Dropping to two or three runs a week leaves you feeling flat and heavy-legged, and the studies that reduced frequency saw smaller gains than the ones that only reduced volume.
Keep intensity. This is the one that surprises people. Some fast running stays in the schedule right up to the final days, in reduced doses: fewer reps, shorter intervals, but at the same pace. It keeps the neuromuscular system sharp and keeps race pace feeling familiar. Remove it entirely and you arrive rested but sluggish.
The rule in one line
Halve the distance, keep the days, keep the speed, shrink the reps. If a session is in your normal week, a smaller version of it is probably in your taper.
A sample three-week marathon taper
Assuming a peak week of around 50 miles with a 20-mile long run and two quality sessions.
Three weeks out, about 80 percent. Long run drops to 14 to 16 miles. Quality sessions stay, with reps trimmed by a quarter. This is still a real training week, and it is the last one.
Two weeks out, about 60 percent. Long run of 10 to 12 miles, with a few miles at marathon pace inside it so the pace stays rehearsed. One quality session of half the normal volume. Easy days shortened.
Race week, about 40 percent. Two or three short easy runs, one session of 4 to 6 short efforts at race pace with full recovery, at least two days before the race, and then a couple of miles with a few strides the day before. Some runners prefer a full rest day two days out rather than the day before, because a very short shakeout run the day before tends to leave the legs feeling better than complete rest does.
If you have not yet settled the goal, the race time predictor converts a recent result into a marathon estimate, and the running pace calculator turns that into the per-mile number you will rehearse in these sessions.
Race week outside of running
The taper is not only a running-volume decision. A few things matter as much in the last seven days.
Sleep. The nights two and three days before the race count more than the night before, which is usually poor anyway. Bank sleep early in the week.
Carbohydrate. For anything over about 90 minutes, increase carbohydrate intake in the final two to three days rather than the night before. You do not need to eat more food in total, only shift the balance towards carbohydrate. The old-style depletion phase is unnecessary.
Nothing new. Shoes, fuel, kit, breakfast, warm-up. Race week is for decisions that have already been rehearsed on a long run.
Easy heart rate. If you train by heart rate, the easy runs this week should sit firmly in the bottom of your range, not at the top of it. The heart rate zone calculator will give you the number if you do not already have it.
Why it feels wrong
Almost everyone hates their taper, and the reasons are physiological rather than mental weakness.
As fatigue clears, muscles that were chronically tired start to feel odd: heavy one day, twitchy the next, with small phantom aches that appear and vanish. Glycogen stores refill and pull water in with them, so you feel slightly heavier and more sluggish, which is exactly the opposite of what you expected freshness to feel like. And with less training to occupy you, there is more time to think about the race.
None of this means the taper is failing. The freshness shows up on race morning, not on the easy runs in between. The runners who panic and add a hard session in race week to "check that fitness is still there" are trading the one thing a taper gives them for reassurance they did not need.
Common mistakes
- Not tapering enough. The most common error among experienced runners, who fear losing fitness far more than they should. Fitness gained in the final two weeks is negligible. Freshness lost is not.
- Cutting intensity along with volume. Leaves you rested but flat. Keep some race-pace running in every week of the taper.
- Over-tapering a short race. A 5K or 10K does not need three weeks. Ten days of reduced volume with a sharp session in it is plenty.
- Cramming. A missed long run three weeks out cannot be made up two weeks out. The block is what it was; the taper is not the place to fix it.
- Racing the taper. Feeling good on an easy run and picking the pace up "because it felt easy" is the taper working. Let it.
- Changing everything else. New shoes, a new breakfast, a new stretching routine because you have time. Race week is for rehearsed decisions only.
The part a schedule cannot tell you
A taper template is a reasonable guess at how much fatigue you are carrying. It does not know whether your last three weeks went to plan, whether you slept, whether your heart rate variability has been holding or sliding, or whether the peak week left you more or less tired than the plan assumed.
Sizing the taper to the runner rather than to the template is the coaching. Vaast does it: it reads how the block actually went, watches your recovery data through the final weeks, and adjusts the reduction so you arrive fresh rather than flat.