Ten days out and my legs feel worse than they did in peak training: is the taper supposed to feel like this?

On what to cut, the principle is consistent across most approaches: cut the volume, keep some of the intensity.

Dropping mileage substantially is the whole point, that is what allows the recovery. But cutting the fast running entirely tends to leave people feeling flat and sluggish, and it is likely part of why your goal pace effort felt wrong. Short bouts at race pace or a little quicker, with plenty of recovery, keep you feeling sharp without adding meaningful fatigue.

A rough shape that works for a lot of people:

• Volume down significantly across the taper, with the biggest cut in the last week
• Keep the frequency, the same number of runs, just much shorter. Stopping running for days is what makes people feel worst
• Keep one short quality session in each of the first two taper weeks, and something very light and brief in race week
• The last few days: short and easy only

On length: two to three weeks is the usual range for a marathon, and shorter distances need less. Three weeks suits high-volume training; two suits most people running moderate mileage. One week is generally too short for a marathon.

What matters more than the exact plan is not adding anything. The taper is subtractive.

This is so common it has a name among runners, and it is not detraining. Ten days is nowhere near long enough to lose fitness - meaningful loss takes weeks, not days.

What is actually happening is that you have spent months with a constant training load, and your body has adapted to that state. Remove the load and it takes time to settle: there is repair happening that was being suppressed, and there is a period where you feel worse before you feel better. Most people report the low point somewhere in the middle of the taper, and it very often resolves in the last few days.

The heavy legs and the bad sleep are both part of the same picture and both extremely common.

The thing not to do is the thing you are tempted by. Adding a long run now cannot improve your fitness, the adaptation from it would arrive after the race - and it can absolutely leave you tired on the day. Every extra session in the last ten days has a large downside and essentially no upside. This is the point where discipline is doing nothing.

One genuine caution: if you feel ill rather than heavy, that is different and worth treating as such. Heavy and flat is the taper. A sore throat is not.

A few practical things for the last ten days, since the training question is now settled and everything left is logistics.

Expect the extra energy to arrive around three or four days out, not immediately. Almost everybody who reports feeling terrible mid-taper reports feeling springy in the final days, and if you know that is coming it is much easier to sit through the bad week.

Do not change anything. Not shoes, not diet, not a new supplement, not a massage you have never had before. Race week is the worst possible time to introduce a variable, and people do it because they are anxious and looking for something to control.

Sleep is worth more than any session now, and it is normal for it to be poor the night before. The nights two and three before the race are the ones that matter, so protect those rather than worrying about the last one.

Plan the boring things, pacing, what you eat and when, what you carry, how you get there. Doing that is a genuinely useful use of the nervous energy, and it is the part that most often goes wrong on the day.

And the reassurance, since I have felt exactly this before every good race I have run: the fitness is already banked. Nothing you do in ten days adds to it. All you can do now is arrive fresh.