If you’re not familiar, the 10% Rule is the idea that you should never increase your weekly mileage by more than 10% to avoid injury. On the surface, it sounds reasonable — even smart. But if you’ve ever trained with me or heard me talk about coaching, you know where this is going:
We are all different, and we need different inputs to reach our individual goals.
So my take? The 10% Rule completely misses the mark.
In fact, a recent study** of over 5,200 runners — with 22% female participants and an average age of 45.8 years — showed that even small mileage spikes can significantly increase injury risk. A 10–30% jump led to a 64% increase in injuries, while spikes of 30–100% led to a 52% increase (yes, slightly lower — welcome to the messiness of human data). And jumps of more than 100% in a single session? That was linked to a 128% increase in injury risk.
It’s clear: arbitrary mileage bumps, even small ones, can be risky if they don’t match your current training load, history, and recovery capacity.
One Size Never Fits All
Let me give you an example. I worked with an athlete last year who’d been running marathons for years using a free online plan. The plan followed a simple progressive mileage model — likely influenced by the 10% Rule. But despite being consistent, they were constantly dealing with overuse injuries.
When they came to me, our priority was to train smarter — not just harder. We built their plan around them — their history, strengths, schedule, and feedback. Fast forward: they not only stayed healthy, but they ran a PR at the California International Marathon and qualified for Boston.
So, why doesn’t the 10% Rule work?
It Ignores Individual Variability
No two athletes are the same. Some adapt quickly to higher mileage, while others need more time. Sticking to a strict 10% increase could either:
Hold someone back unnecessarily, or push someone into injury territory. Your training should reflect your unique physiology, history, and recovery ability — not a cookie-cutter formula.
It Doesn’t Account for Life
Mileage isn’t the only stress your body is handling. What about: Sleep (or lack of it)? Work deadlines? Family stuff? Weather? Terrain?
If you increase your mileage by 10% and add an extra speed session and only sleep 4 hours a night… that 10% just became a lot more than your body can realistically absorb. Context matters. Always.
It Discourages Intuitive Training
Blindly following a plan can train you to ignore your body’s signals.
Another athlete came to me training for their first 50K. They were terrified they wouldn’t finish, so they stuck religiously to an online plan based on — you guessed it — the 10% Rule. When their body started sending warning signs (fatigue, soreness, nagging pain), they kept pushing through.
The result? Injuries and water jogging as their only cardio for the last month.
Soreness, pain, fatigue — that’s feedback. You need to pay attention to it, not override it.
Progress Isn’t Linear
Your fitness doesn’t go up in a straight line. It’s more like a squiggly one: progress, plateaus, setbacks, breakthroughs. Some weeks you’ll feel unstoppable. Others, you’ll feel like a slug. That’s normal.
If you expect to increase every single week, you’re setting yourself up for frustration — or worse, burnout.
Long-Term, It’s Just Not Sustainable
Even over a 12-week training cycle, a consistent 10% increase (with deloads) leads to a 135% jump in mileage. That’s a lot.
Unless you’re starting at very low mileage, most runners simply can’t — and shouldn’t — handle that kind of build. Eventually, the math just doesn’t add up to sustainable, injury-free training.
So What Does Work?
My approach with athletes is based on adaptation, not arbitrary rules. Here’s the framework:
Keep mileage steady for three weeks.
Deload for one week.
If those three weeks felt strong and manageable: bump up mileage — a good starting point is 10%, and sometimes by a bit more than 10%.
If they felt anything other than great for those three weeks: a smaller increase (5%) — or maybe none.
If signs of fatigue or overuse show up: we don’t increase, and we might even back things down.
This model respects the body’s natural rhythms and allows time for adaptation. It’s sustainable, personalized, and — most importantly — it works.
Run Your Race
If there’s one thing I hope you take away from this, it’s this: training isn’t about following rigid rules — it’s about learning to listen to your body. The 10% Rule is a fine starting point for beginners, but it falls apart quickly for real-world athletes with real-world lives.
So ditch the rigidity. Tune into your body. Trust the process. And train like the unique human you are.
If you’re getting ready for an endurance event — don’t wait until the last month to reach out. The earlier we start, the better we can understand how your body responds and get you to the start line strong, healthy, and ready to crush it.
Let’s build you up — the right way.
**https://bjsm.bmj.com/content/early/2025/07/07/bjsports-2024-109380
How much running is too much? Identifying high-risk running sessions in a 5200-person cohort study
