Races and distances

When to start preparing your race

Most plans fail before the first session, because the block started too late and everything had to be squeezed. Counting back from the date is the dullest and most useful thing you will do.

Updated October 28, 2026 · 4 sources

Counting back

GoalFrom a regular running baseBuilding the base too
10 km8 to 12 weeksAdd 6 to 8 weeks
Half marathon10 to 16 weeksAdd 8 to 10 weeks
Marathon12 to 20 weeksAdd 10 to 12 weeks
Trail, 20 to 55 km12 to 18 weeksAdd 8 to 12 weeks
Trail, 70 km and up16 to 24 weeksAdd 12 weeks or more

These are conventions, and we label them as such. No study has compared plan lengths against each other.

What the evidence does support: the last stretch should be a taper 1, and how fast you add volume is where the risk sits 23.

What to do before the block starts

The weeks before a plan are the cheapest place to buy yourself a better block.

  • Get regular before you get serious. Three to five easy runs a week for a month beats a heroic first week of the plan.
  • Fix the niggle. Something you have been ignoring will not survive twelve weeks of building.
  • Find your real paces. Not the ones you would like. A plan written on wishful numbers falls apart in week four.
  • Enter the race. An ambition that is not on a calendar quietly becomes next year.

Fitting it round a life you already have

The plan you finish beats the plan that was optimal.

Decide before the block how many days a week you can genuinely run. Build the plan on that number, not the one you wish you had.

Four running days with two real sessions, done for sixteen weeks, takes almost any runner further than six days attempted for five weeks and abandoned.

The same goes for disruption. Travel, a bad cold, a rough month at work — these are normal. A block that cannot absorb them was badly built. And you lose fitness far slower than you fear: a missed week is not a lost block 4.

How we handle this

Every plan starts from your race date and works backwards.

The number of training days comes from you, not from a template. Where the evidence is thin — plan length, long-run distance, how fast to build — we use conventions and say so, rather than passing a convention off as a finding.

Every race page on this site shows the date and counts back to the week a block would need to begin.

Questions people actually ask

I have eight weeks until my marathon. What now?
Change the goal rather than squeezing the plan. Eight weeks can get a regular runner to a comfortable finish. It cannot safely build a time target from a low base.
Can I shorten the taper to fit more training in?
You can, and it usually costs more than it gains. Less volume with the same intensity produces a measurable improvement {{bosquet2007}}. The sessions you would add instead do not.
What if I miss two weeks in the middle?
Rejoin where the plan is, not where you left it, and expect a rusty week. Losses over that timescale are small {{mujika2000a}}.
How many days a week do I need to run?
Enough to be consistent, which is personal. What matters more is that the plan was built for that number rather than shrunk down from a bigger one.

References

Every figure above rests on one of these studies. Author and year are enough to find the paper.

  1. Bosquet (2007)
  2. Nielsen RØ (2014)
  3. Buist (2008)
  4. Mujika (2000)

Your race is on the calendar. Your plan should be too.

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