Why weekly mileage progression matters
Most running injuries are overuse injuries: tendons, bones and connective tissue adapt more slowly than your heart and lungs, so fitness can outpace durability. Increasing weekly volume too quickly is one of the most common patterns behind shin splints, stress reactions, Achilles and knee problems. A steady progression with regular easier weeks gives tissues time to adapt.
The 10 % rule — useful, but not magic
The classic guideline is to increase weekly mileage by no more than 10 % from one week to the next. It is conservative and easy to follow, which is why coaches use it. But research has not found it to be protective on its own: a 2008 randomised trial of novice runners by Buist and colleagues found a graded 10 % programme did not reduce injuries compared with a standard programme. A 2014 study by Nielsen and colleagues suggested that novice runners who increased weekly distance by more than about 30 % over two weeks were more likely to suffer certain injuries.
The practical message: steady, moderate increases with regular cutback weeks are sensible, and sudden spikes — doubling your volume after a holiday, or adding a big race week on top of normal training — are the pattern to avoid.
Example build-up: 30 to 60 km per week
| Week | Volume (km) | Week type |
|---|---|---|
| 1 | 30.0 | Build |
| 2 | 33.0 | Build |
| 3 | 36.3 | Build |
| 4 | 27.2 | Cutback |
| 5 | 39.9 | Build |
| 6 | 43.9 | Build |
| 7 | 48.3 | Build |
| 8 | 36.2 | Cutback |
| 9 | 53.1 | Build |
| 10 | 58.5 | Build |
| 11 | 60.0 | Peak |
With 10 % increases and a 25 % cutback every fourth week, doubling weekly volume takes around 11 weeks. That is why marathon plans typically last 16–20 weeks and assume you already have a base.
The acute:chronic workload ratio (ACWR)
The ACWR compares what you did recently with what your body is used to. In its simplest form:
chronic load = average weekly volume over the last 4 weeks
ACWR = acute ÷ chronic
The ACWR has been debated by researchers — the ratio has statistical limitations and much of the evidence comes from team sports rather than running. Still, it is a simple, useful way to notice when a week is far bigger than your recent normal.
Smart ways to add volume
Add easy running
Increase volume with easy miles first. Keep hard sessions roughly the same while volume rises.
Add a day before adding length
Going from 3 to 4 runs a week spreads load better than making every run longer.
Cap the long run
Many coaches keep the long run at roughly 25–35 % of weekly volume.
Listen to warning signs
Localised pain that worsens during a run, or lingers into the next day, is a signal to back off.
Individual differences. Age, running history, body weight, sleep, footwear and surface all influence how much training you can absorb. Use these numbers as a starting point and adjust to how your body responds.
Once your volume is set, fill it with the right intensities using the VDOT training pace calculator and keep easy days easy with the heart rate zone calculator. Our goal pace charts list typical weekly volumes for popular race goals.
- Buist I et al. (2008). No effect of a graded training program on the number of running-related injuries in novice runners. Am J Sports Med 36(1):33–39.
- Nielsen RØ et al. (2014). Excessive progression in weekly running distance and risk of running-related injuries. J Orthop Sports Phys Ther 44(10):739–747.
- Gabbett TJ (2016). The training–injury prevention paradox. Br J Sports Med 50(5):273–280.
Last reviewed: September 2026 · Health disclaimer