Trail Running Myth: The 10% Rule

At some point in history, some dude (seriously, no one even knows who) said runners should only increase their mileage by 10% each week. No studies. No science. Just a number tossed out that somehow caught fire and turned into “the rule.”

And I get it — rules feel safe. They give us structure, something to cling to when everything else feels uncertain. But let’s be honest: the 10% rule doesn’t hold up. Especially for trail runners.

Why the 10% Rule Doesn’t Make Sense for Trail Runners

Imagine this for a second…

You’re a brand new runner. You finally get brave enough to lace up your shoes, squeeze in a 2-mile loop before the kids wake up, and you’re feeling pretty proud. Next week, the “rule” says you should add 10%. That’s… what? A quarter mile? You’d barely make it to the next stop sign before turning back. (And let’s be real — you’d probably spend longer fiddling with your watch to prove you went that extra .25 than actually running it.)

Now flip it. Say you’ve been running for years, averaging 60 miles a week. Ten percent is six more miles. That’s like tacking on another medium-long run every single week. And then the next week? Another six. Before long you’re running on fumes, Googling “is it normal for my legs to feel like concrete?” and pretending your foam roller is actually doing something.

The 10% rule doesn’t care that you’re a human being with stress, hormones, or a boss who suddenly needs three reports by Friday. It doesn’t care that your trails are rocky, steep, and take way more effort than a flat bike path. It’s a one-size-fits-all rule… and humans don’t work that way.

The Same Goes for the “3 Weeks On, 1 Week Off” Rule

That’s another catchy soundbite that spread like wildfire. And just like the 10% rule, it’s not a hard-and-fast truth. For some people it works, for others it doesn’t. Training cycles are a whole conversation in themselves, so I’ll save the deep dive for another blog — but just know this: there is no one magic formula.

How to Progress Your Trail Running Smarter Than the 10% Rule

Instead of clinging to myths, here’s the smarter way to train for trail running:

• Think in time on feet, not just miles. Trails aren’t uniform. A 7-mile road run might take the same time as a 4-mile rocky climb. Your body adapts to stress, not just numbers.

• Progress in steps, not leaps. Sometimes you increase by 20%, sometimes by 5%. It depends on your background, how your last run felt, and what else is going on in your life. The point is steady steps in the right direction, not rigid jumps.

• Adjust to your real life. Kid sick? Work project exploding? Hormones making everything harder this week? That matters. Training doesn’t live in a vacuum — it lives right alongside your 6 a.m. alarms, that Slack message from your boss, and your kid telling you they need a poster board for school tomorrow at 8:30 p.m.

  
  

Why the 10% Rule Fails Everywhere

Here’s the thing: we do this in other areas too.

You don’t grow your career by adding exactly 10% more hours each week. If you tried, you’d end up exhausted, burned out, and probably resenting your job.

You don’t build relationships by scheduling 10% more date nights or phone calls. That’s not how connection works.

You don’t heal by stacking 10% more self-help books on your nightstand (they’ll just glare at you while you doom-scroll instead). Healing happens in cycles — push, rest, absorb.

Real progress — in training, in life, in anything — happens in waves. It’s step forward, step sideways, sometimes even a step back. But if the steps are in the right direction, you’re still moving forward.

That’s how you get stronger on the trails. That’s how you build habits that actually last. That’s how you move forward in life without burning out or breaking down.

So yeah — ditch the fake math. Take the steps that make sense for you. Some weeks that’s forward. Some weeks it’s sideways. Some weeks it’s a giant leap you didn’t see coming.

The only “rule” that matters? You’re still moving in the right direction.

Good effort. Positive attitude. 💛🧡⛰️