How to taper for a race: what the research says about the final weeks

You have done the long runs, the intervals, the weeks of patient mileage. The last two or three weeks before a race feel like the time to cram in a final hard effort. They are not. They are the time to let the work surface. This is the taper, and there is a surprising amount of good science on exactly how to do it.

What a taper is for

A taper is a progressive reduction in training load designed to shed the accumulated fatigue of hard training while keeping the fitness. Mujika and Padilla (2003), in the standard reference review, describe it as a way to reduce physiological and psychological stress so the body can supercompensate before competition. The fitness was built weeks ago. The taper is about arriving fresh enough to use it.

How long, and how much to cut

The clearest single answer comes from Bosquet et al. (2007), a meta-analysis of 27 studies. Performance was maximised by a taper of about two weeks in which training volume was reduced progressively by 41 to 60 percent. Cutting much less left residual fatigue. Cutting much more, or stopping abruptly, started to erode fitness. A gradual, exponential wind-down beat a sudden drop.

Real-world data agree and add nuance. Smyth and Lawlor (2021) analysed 158,117 marathon runners on Strava and found that a disciplined three-week taper was associated with a finish roughly 2.6 percent faster, about five and a half minutes for a typical recreational marathoner. Strict tapers beat relaxed ones, and longer beat shorter up to about three weeks.

Keep the intensity, keep the frequency

Houmard et al. (1994) gave distance runners a 7-day taper that slashed volume by 85 percent but kept high-intensity intervals. Their 5 km time improved by 3 percent and the oxygen cost of submaximal running dropped by 6 percent. The volume came off; the sharpness stayed on.

Mujika and Padilla (2003) add a second rule: keep training frequency roughly intact, reducing it by no more than about 20 percent. You want fewer and shorter sessions, not fewer running days. Disappearing from running for a week breaks the rhythm and tends to leave you stale.

What is happening inside your body

The taper is not just rest. Luden et al. (2010) took muscle samples through a three-week run taper and found the fast-twitch fibres grew in diameter by about 7 percent, single-fibre peak force rose by 11 percent, and power increased by 9 percent, while the molecular markers of muscle breakdown were blunted. Crucially, aerobic fitness did not fall. The muscle was actively repairing and getting stronger.

Wang et al. (2023), in a more recent meta-analysis, found that tapering improves time-trial and time-to-exhaustion performance without necessarily raising VO₂max or running economy. The gains are largely muscular and neuromuscular, supported by expanded blood and plasma volume, restocked muscle glycogen, and a more anabolic hormonal balance. For the marathon specifically, the chance to fully replenish glycogen matters, since Rapoport (2010) showed carbohydrate depletion is what limits a large share of marathoners late in the race.

Taper by race distance

Spilsbury et al. (2015) documented how elite British runners actually taper, and the pattern scales with distance. Marathoners tapered longest, around 14 days, and cut their continuous running volume the most, to roughly half of normal. Middle and long distance track runners tapered for about 6 days and trimmed less. Notably, even as volume fell, these athletes pushed their hardest intervals to 112 to 114 percent of race pace. A workable translation:

• Marathon: taper 2 to 3 weeks, cut volume to roughly half by race week, keep intensity.
• Half marathon: taper around 10 to 14 days, similar volume reduction.
• 5K to 10K: taper 7 to 10 days, slightly less volume cut, sharp short intervals retained.

Common taper mistakes

The errors are predictable. Resting too completely, which blunts the adaptation rather than sharpening it. Cutting intensity instead of volume, which loses fitness. Tapering far longer than three weeks or shorter than one. And, for the marathon, overeating across the whole taper rather than topping up carbohydrate strategically in the final days, since your energy needs fall as volume drops. A taper is a controlled wind-down, not a holiday.

One more point worth keeping in perspective: a taper sharpens the fitness you already have. If you want a clear-eyed view of what finish time that fitness actually supports, see how accurate race time predictors really are.

Frequently asked questions

Related reading: VO2max for runners: what it is, what is good, and how to improve it.