How much does tapering actually matter?

Tapering is one of those running rituals that understandably gets a lot of attention. For weeks you build up your mileage, nail your long runs, fine-tune your pacing — and then suddenly you’re supposed to pull back. The “perfect taper” is meant to be the secret weapon that unlocks your best marathon performance.

But how much difference does it really make?

A big data study published in Frontiers in Sports and Active Living looked at exactly that. Researchers analysed the tapering patterns of thousands of runners using Strava data, and the results are not quite as dramatic as you might think.

What the science says

The researchers looked at the training data of over 158,000 marathoners to see how their tapering affected performance. They compared how runners reduced their training volume in the weeks before race day, and they controlled for sex and fastest 10k pace — which, unsurprisingly, turned out to be the biggest predictor of marathon time.

Here’s what they found:

• Runners who did strict, longer tapers — steadily cutting down training for two to three weeks — performed best.

• The difference between a relaxed two-week taper and a strict three-week taper was roughly two minutes faster.

• The best result, a strict three-week taper, was about four minutes quicker than a one-week taper.

• A four-week taper was actually less effective, suggesting you can taper too much.

So, there are gains to be made with strict, controlled tapers.

What that means in real life

The paper states that you can make up to 4 minutes by doing a strict 3 week taper, as compared with a one week taper. Runners will need to decide what works best for them — for runners who have been training hard, consistently for a longer period of time, then a longer taper will likely benefit them. Runners who have a shorter training block may benefit from training harder until closer to race day (1 week out).

To put it in context, drafting (tucking in behind another runner to save energy) can save up to a similar amount of time. We’ve got a video on that too, if you fancy the science behind it.

The point is, tapering matters, but you need to have done the training to benefit from it.

The Kaizen takeaway

Tapering works, although it is dependent on personal circumstances. Kaizen's algorithms give you a race prediction from 1 week out from the race and our race plans build your fitness up until that point. So if you want to do a longer taper, then it's best to set a more aggressive goal (or "fake" the date of your race to be a week or two earlier).

Over time, we'll aim to have a custom taper period to support runners' personal preferences.

FAQs: How to Taper Before a Marathon

1. What is tapering, exactly?

Tapering means reducing your training load in the final weeks before a race so your body can recover, adapt and perform at its best. You still run, just with less volume and more rest.

2. How long should a taper last?

Two to three weeks works well for most runners. The research suggests three weeks is best, but the difference between that and a good one-week taper is small.

3. How much should I reduce my mileage?

Cut your peak training volume by about 30 to 50 per cent. Keep a bit of intensity short tempo or marathon pace efforts but skip the long runs or unnecessary extra miles.

4. What if I only have time for a short taper?

No problem. A one-week taper still gives most of the benefit. Focus on recovery, nutrition and a few short runs to stay confident.

5. Should I stop strength training during taper?

Not necessarily. Reduce the volume and avoid anything that leaves you sore, but light maintenance work can keep you balanced.

6. What mistakes should I avoid?

Doing too much: a big last long run can leave you flat.

Doing too little: total rest for two weeks can make you sluggish.

Overthinking: small details won’t make or break your race.

7. Can tapering ever hurt performance?

Only if you overdo it. Four weeks or more of reduced running can make you lose rhythm and fitness. One to three weeks is the sweet spot.

8. Should I change how I eat or sleep during taper?

Yes. Prioritise sleep, hydration and balanced meals. You’ll burn fewer calories, so reduce portions slightly but keep carb intake steady, especially in the final few days.

The bottom line

Tapering helps, but it needs to be weighed up alongside other factors. A consistent training block, solid recovery and good pacing will always matter more. Keep your taper simple, trust the process and show up fresh rather than frazzled.

🎥 Watch: Josh breaks down how much tapering really matters before your marathon →