If you’ve been running for any length of time, you’ve probably heard the 10% rule: don’t increase your weekly mileage by more than 10% from one week to the next.
It’s easy to understand and calculate, and gives runners a concrete number when they’re trying to decide how quickly to build their training. That probably explains why it’s stuck around for so long.
The problem is that research has never established 10% as a universal threshold for preventing running injuries. Gradual progression is still a reasonable principle, but your body doesn’t suddenly become protected because this week’s mileage increase was 9% instead of 11%.
A large 2025 study also suggests that looking only at weekly mileage may miss an important part of the picture. The distance of an individual run compared with your longest run over the previous 30 days may tell us more about injury risk than the traditional week-to-week calculation.
What Is the 10% Rule for Running?
The 10% rule says that your total weekly running distance shouldn’t increase by more than 10% compared with the previous week.
If you ran 30 kilometres this week, you’d cap next week at 33 kilometres. If you ran 50 kilometres, you’d increase to a maximum of 55.
That percentage can also mean very different things depending on how much you’re already running. For a beginner running 5 to 10 km per week, a 10% increase is only 500 metres to 1 kilometre. That’s too small an increase to create meaningful adaptation on its own, and it can make progression unnecessarily slow. For someone already running 70 or 80 km per week, a 10% increase adds 7 to 8 km in a single week, which may be a substantial jump depending on their recent training and how that mileage is distributed.
Using the same percentage for both runners ignores the size of the actual increase and the training history behind it.
Does the 10% Rule Prevent Running Injuries?
I want to start by saying there are no guarantees that anything can “prevent” injuries. And researchers have questioned the 10% rule for years.
A 2008 randomized controlled trial followed 532 novice runners preparing for a recreational running event. One group completed a 13-week training program based on the 10% rule, while another followed a standard eight-week program with faster progression.
The injury rates were almost identical: 20.8% in the 10% group and 20.3% in the standard training group.
A 2022 systematic review looked at 36 prospective studies involving more than 23,000 runners. The evidence linking running injuries with weekly distance, duration, frequency, intensity, and changes in those training variables was inconsistent. The researchers cautioned against recommending universal progression rules based on the available evidence.
A 2025 Study Looked at Running Distance Differently
In 2025, researchers published one of the largest studies to date examining changes in running distance and overuse injuries.
They followed 5,205 runners for up to 18 months and collected data from 588,071 running sessions using Garmin devices.
The researchers compared three different ways of looking at changes in running distance:
- The distance of each individual run compared with the runner’s longest run during the previous 30 days
- Week-to-week changes in total running distance
- Acute-to-chronic workload ratio, which compared recent weekly mileage with mileage over a longer period
The clearest association with overuse injury appeared when they looked at individual running sessions.
Compared with runners who stayed within 10% of their longest run from the previous 30 days, the rate of overuse injury was higher when a single run increased by more than 10%. Runs that were more than double the runner’s recent longest distance were associated with more than twice the rate of overuse injury.
Week to week changes in total running distance weren’t associated with an increased injury rate.
What Does the 30-Day Finding Mean?
Say your longest run over the past 30 days has been 10 km, and this weekend you decide to run 15 km.
That’s a 50% increase in the distance of a single session compared with the longest run your body has recently experienced.
Your weekly mileage may not look particularly unusual. You could shorten another run and finish the week with roughly the same total distance as usual. Looking only at weekly mileage would miss the fact that your longest individual exposure increased substantially.
For runners building a long run for a half marathon or marathon, returning after time off, or suddenly adding longer weekend runs, this is worth keeping in mind.
Is the Longest Run From the Past 30 Days the New 10% Rule?
I wouldn’t treat it that way. The 2025 study was observational, so it identified associations between changes in running distance and overuse injuries. It can’t establish that crossing one particular percentage directly causes an injury.
There are a few other reasons to be careful with the 10% number. The researchers selected 10% as one of their cutoffs partly because of how widely the traditional 10% rule is used in running. In a sensitivity analysis using smaller categories, increases between 1% and 10% were also associated with an increased injury rate.
That makes it difficult to argue that 10% has suddenly become a scientifically validated threshold, only applied to a different calculation.
The study population was also only 22% female, and distance was the training variable being analysed. Pace, intensity, hills, terrain, recent injury, and other factors can change the demands of a run, and therefore injury risk, even when the distance stays the same.
How Should You Use This Research in Your Own Training?
I’d start by paying more attention to what you’ve actually been doing recently, particularly when planning your longest runs.
If your longest run in the past month has been 12 km, jumping straight to 18 km represents a substantial change in one session.
When you’re planning an increase, consider:
- Your longest run over the previous month
- How consistent your recent running has been
- Whether you’ve recently had time off because of illness, injury, travel, or life getting busy
- Whether the planned run also adds hills, speed, technical terrain, or a different surface than what you usually run on
- How you’ve been recovering from your current training
- Whether pain or other symptoms are already developing
You also need enough time between increases to adapt to the training you’ve already completed. Ensuring that you stay within a certain percentage doesn’t tell you whether that adaptation has occurred.
Should You Still Track Weekly Mileage?
Yes for sure. Weekly mileage gives you a simple way to follow your overall running volume and see how your training changes over time.
Pair it with the demands of your individual sessions. A week containing five fairly even runs creates a different pattern of exposure from a week where a large percentage of your mileage is packed into one long run.
The same applies to intensity and terrain. 10k of easy running on familiar terrain creates a different training demand than 10k of hard intervals or steep trail running.
Why There Isn’t One Perfect Mileage Increase for Every Runner
Your recent training history influences how much running you’re prepared for.
A runner who has consistently trained at 40 to 50 km per week for several years has accumulated a different training history from someone returning after six weeks away from running, even if both previously had similar fitness.
We’re all different individuals. Shocking, I know.
Recovery, previous injuries, sleep, fuelling, strength, and everything else going on outside running can also affect how well you tolerate your current training.
If you want to go deeper into that relationship, read Why Runners Get Injured: Understanding Load vs Capacity
The Bottom Line on the 10% Rule for Running
The 10% rule gives runners an easy reminder that training should generally progress gradually, but research doesn’t support it as a universal injury-prevention threshold.
The 2025 study gives us another practical piece of information to consider. Large increases in the distance of a single run compared with the longest run from the previous 30 days were associated with higher rates of overuse injury, while week-to-week mileage changes weren’t.
Pay attention to your recent longest runs, your overall training, and how your body is responding as you progress. There still isn’t one percentage that can make that decision for every runner.
Key Takeaways
- The traditional 10% rule recommends increasing weekly running mileage by no more than 10%.
- Research has not shown that following the weekly 10% rule reliably prevents running injuries.
- A 2025 study of 5,205 runners found higher rates of overuse injury when a single run exceeded the runner’s longest run from the previous 30 days by more than 10%.
- Week-to-week mileage increases weren’t associated with higher injury rates in that study.
- The study doesn’t establish 10% as a new cutoff for individual runs.
- Recent training, long-run distance, intensity, terrain, recovery, and time away from running can all influence how you approach progression.
Want to Build More Capacity for Your Running?
Progressing your running is one part of preparing your body for longer runs, harder workouts, and race training. Strength training can help build the muscular capacity to support those demands alongside your running.
My running-specific strength programs are designed to fit into an already busy training week, with options for runners at different experience levels.
Frequently Asked Questions about the 10% Rule for Running
The 10% rule recommends increasing your total weekly running distance by no more than 10% compared with the previous week. It’s commonly used as a guideline for gradual progression, although research hasn’t established 10% as a universal injury-prevention threshold.
Current evidence doesn’t show that following the 10% rule reliably prevents running injuries. A randomized trial in novice runners found almost identical injury rates between runners following a 10%-based progression and runners following a faster training progression.
There isn’t one percentage that works for every runner. Your recent training history, longest runs, intensity, terrain, recovery, injury history, and time away from running can all influence how quickly you’re ready to progress.
A 2025 study found higher rates of overuse injury when an individual run was more than 10% longer than the runner’s longest run during the previous 30 days. The study supports paying attention to sudden increases in individual running sessions, although it doesn’t establish a guaranteed safe cutoff.
There isn’t enough evidence to recommend 10% as a universal long-run progression. The size of the increase, your recent longest run, overall training, intensity, terrain, recovery, and previous running exposure should all be considered.
References
Buist, I., Bredeweg, S. W., van Mechelen, W., Lemmink, K. A., Pepping, G. J., & Diercks, R. L. (2008). No effect of a graded training program on the number of running-related injuries in novice runners: a randomized controlled trial. The American journal of sports medicine, 36(1), 33–39. https://doi.org/10.1177/0363546507307505
Schuster Brandt Frandsen, J., Hulme, A., Parner, E. T., Møller, M., Lindman, I., Abrahamson, J., Sjørup Simonsen, N., Sandell Jacobsen, J., Ramskov, D., Skejø, S., Malisoux, L., Bertelsen, M. L., & Nielsen, R. O. (2025). How much running is too much? Identifying high-risk running sessions in a 5200-person cohort study. British journal of sports medicine, 59(17), 1203–1210. https://doi.org/10.1136/bjsports-2024-109380
Fredette, A., Roy, J. S., Perreault, K., Dupuis, F., Napier, C., & Esculier, J. F. (2022). The Association Between Running Injuries and Training Parameters: A Systematic Review. Journal of athletic training, 57(7), 650–671. https://doi.org/10.4085/1062-6050-0195.21
