The 10% Rule for Weekly Mileage and Recovery Weeks

How a 10% weekly increase compounds

Each week's increase applies to a bigger base than the last, so the growth is exponential. The week-n distance is the starting distance multiplied by 1.10 for each week of increase.

week n distance = start × 1.10 ^ (n − 1)

Worked example: start at 30 km in week 1. Week 2 is 33.0 km, week 3 is 36.3 km, week 4 is 39.9 km, and by week 8 you are at 30 × 1.10^7 = 58.5 km. Distance roughly doubles every 7.3 weeks, and if you could keep it up for 12 weeks you would be running about 85.6 km a week.

Few people can or should keep that going. The rule works as a speed limit on any single week, not as a schedule to follow week after week.

Where the rule falls short

• The size of the base matters. 10% of a 10 km week is 1 km, which is a trivial step. 10% of an 80 km week is 8 km, a lot of extra running in one week.
• It counts distance only. A week with the same distance but more speed work, hills or one very long run is a bigger jump in stress than the number suggests.
• It is a guideline, not a proven safety limit. Evidence that the exact 10% figure prevents injury is limited, and individual tolerance varies with experience, age, sleep, other stress and injury history.
• It ignores how you feel. Persistent soreness, heavy legs or a rising resting heart rate are reasons to hold back even when the arithmetic says you can add more.

Some runners apply the same idea to time instead of distance, which suits trail running and run-walk plans where distance is a poor measure of effort. A 4.5-hour week plus 10% is 4.5 × 1.10 = 4.95 hours, or 4 hours 57 minutes. The arithmetic is identical, whichever unit you choose.

Building in recovery weeks

Many training plans follow two or three weeks of building with one lighter week, so the body can adapt to the extra work. A common cut-back is around 20% to 30% less distance than the previous week. Here is an eight-week example built on the 30 km start, using a 25% cut:

Week 5 is a large jump from week 4 (about 47%), but it is only 10% above the last full week of training, and it follows a week of reduced load. The plan totals about 295 km over eight weeks against about 343 km for continuous 10% growth, and its peak week of 48.3 km is some 17% lower than the 58.5 km that the unbroken plan reaches by week 8.

Putting it into practice

• Base each build week on the last build week, not on the recovery week.
• After a break from running, base the plan on what you have done recently, not on your old peak. Restarting at the weekly distance you ran before three weeks off is a much bigger step than it looks.
• Keep most runs easy enough to hold a conversation, and space hard sessions apart.
• Plan a lighter week after a race, a stressful period at work or a run of poor sleep, even if it is not on the schedule.
• Stop and get advice if pain is sharp, gets worse as you run, or lingers for several days.

To check a week-to-week change, divide the difference by the earlier week: the percentage increase calculator does this for any two numbers, and the percentage calculator finds a 75% cut-back target.

This article is general information for recreational runners, not medical or coaching advice. If you are returning from injury, have a health condition or are unsure how much running suits you, talk to a doctor or qualified coach.