The 10 Percent Rule: What It Is & How To Use It

The 10-percent rule (10PR) states that a runner should never increase weekly mileage more than 10 percent over the previous week. The goal of this rule is to prevent overuse injuries that often occur when runners increase mileage too quickly. 

The easiest illustration of the 10% rule is that if I ran 20 miles last week, I can safely run 22 miles next week.

Brief History of the 10% Rule

According to Podium Runner, the origin of the 10% rule is unclear. What is clear, however, is why it was created. “The genesis was injury prevention by preventing the ‘Terrible Toos: Too much, Too soon, Too hard.’”

There have been studies that set out to check the validity of the 10% rule. Between both of these studies, done at universities, almost 700 were included.

The athletes who increased their mileage by 20 or 30% did not have any higher rate of injury than those who stuck to the hallowed 10% rule.

How to Apply It to a Training Regimen

When you are creating your training plan, if you are following the 10% rule, you will use some simple math to determine how you will increase mileage. Take the mileage increase into consideration in regards to both your long run and overall weekly mileage. 

As a coach, if I am working on a plan for a runner to train for a 10K, I will inquire how many miles the athlete is currently running each week.

For someone running 12- 15 miles each week, a training plan might look like this with a long run of 4 miles. Assume that you are running anywhere from 3 – 3.5 miles including warm-up and cool down when you do a speed workout.

Problems With the 10% Rule

According to Podium Runner, the 10% rule is over-conservative. Think about it for a second. If you are a brand new runner, it would take you forever to build up to where you could jump into a training plan.

The above image comes from the United Endurance Sports Coaches Academy. As you can see, their recommendations allow for a far more aggressive increase in mileage.

If you are following this, you need to be looking at it from the lens of total weekly mileage, not how much you can add to your long run for the week. 

Advice From Coaches 

As running coach Jason Fitzgerald says, “As a more experienced runner, adapt the 10% rule to fit your schedule. Sometimes adding 10% of your mileage works – like going from 50 to 55 miles after becoming very comfortable with that volume.

But if you are adding another day of running, your mileage may increase by 15 or 20%. Advanced runners will find that they have a mileage sweet spot. This particular volume will be comfortable for you but moving past it will be a challenge. 

You may find yourself increasingly tired, prone to injury, or running poorly in workouts.”

Luke Humphrey, head coach of Hanson’s Coaching Services, uses the below image to illustrate how an athlete can increase by 10, 20, or 25%.

As you can see, you can increase by a higher percentage when you are running lower mileage. Conversely, as you start to get into higher mileage numbers, a 25 or 30% increase is far more substantial and is more likely to result in injury. 

According to Humphrey, “Think about it this way. At lower mileage, you have a lot more room. You may be able to add another day for a couple of the increases. Then, start increasing your long run on the weekend, then a mile to a weekday run, etc.

Eventually, you’ll get to a point where you simply can’t just add another day or more mileage to your runs. You’ll also be at a point where you are doing structured workouts and so you’ll be increasing your training load based on that, too.

So, increasing your mileage while doing workouts means you’ll be adding volume, frequency, and intensity. Increase all three by too much at the same time and that is where the body begins to break down.”

RunnerclickPro athlete, coach, and marathon pacer Jeff Picken agrees with the 10% rule. Picken says, “One caveat to spell out for those that train 2 or 3 wks up then 1 wk down: one should use the max from the previous ‘up’ week in the calculation, rather than the previous week (down wk) or they’d never get anywhere.”

Additional Things to Consider

Should New Runners Apply the 10% Rule?

The 10-percent rule works for new runners in some ways, and not in others. Hear me out. If you are brand new to running but in good cardiovascular shape, you might head out for 20 minutes on day one. 

Let’s say that in 20 minutes you can jog most of it, and you travel 1.75 miles. If you do that 4 times one week, then the next week decide to increase your time on feet to 30 minutes each time you run, you are most likely increasing by more than 10%. 

Anyone following the Couch to 5K (C25K) and keeping track of the miles traveled in a week has seen that you can increase your mileage pretty quickly from week to week if you remain consistently dedicated to the process. 

If you are doing so injury-free, keep moving! 

What if You Are Out of Shape

If you are very new to running and/or any cardiovascular activity, you may need to take it slower than the 10% rule would have you increase. 

There is a reason why sometimes a physician or coach will caution you to take it very, very slowly. This is true for people with health conditions and sometimes holds true if you have a significant weight issue. 

I typically encourage new runners to do the same distance (or time out) at least 3 or 4 times before they try to add to it. This can help you prevent injury as well as help to build a base. 

When you are new, getting some consistency in your workouts is way more important than worrying about how far you get in a week!

What if You Take a Break From Running?

Sometimes, runners just take a short hiatus from running. Maybe you twisted an ankle or perhaps you had a nasty stomach bug. Thinking back to when I had Covid-19, I had no choice but to take a complete break from all exercises. 

I was consistently logging 18-20 miles each week when I got sick. I barely moved from my bed for almost a full week and lounged around on the couch for the remainder of my quarantine. 

After close to two weeks of inactivity, the doctor gave me the “all clear” to start working my way back. My first week back running I ran maybe 9 miles. The second week I had 15. In the third week, I ran 22. 

As you can see, that defies the 10% rule. Why could I manage to do that without problems? Because I had the benefit of a consistent running base and my body was acclimated to that amount of miles. 

Increasing back up to where you were after a short break is not the same as someone who has never done the mileage or is returning after a very long time off. 

Coming Back From Injury

If you are returning after a significant injury that has sidelined you, you may need to come back slower than the 10% rule. After a stress fracture, a friend was told to take it very, very slowly. 

She was in a boot for 2 months and even though she had a great baseline, her doctor encouraged her to keep her mileage low for the first month back. She was also told to alternate running with non-impact cardio as she worked her way back. 

Ignoring the 10% rule, she simply ran when the schedule allowed her to. Her running miles were shorter and easier than normal. She did her hard cardio workouts on her bike or the elliptical.

As someone acclimated to high mileage, she found this frustrating at times. But guess what? Her recovery went great. 

What’s Your Baseline?

Coaches recognize that most runners have a baseline. Mine appears to be 20-25 miles in a week. If I take a break from running I can swiftly increase back up to the 20-25 without injury because my body is pretty comfortable there. 

If I try to jump up to 30+ miles in a week and hold mileage there consistently, my body is less happy. I am not saying I could not do that, just that my body would need more time and a concerted effort to hold there week after week. 

Friends of mine who are consistently in distance training for marathons have a higher baseline number than I. After running 50-55 miles each week, they can drop down for a few weeks if they are busy or vacationing, then can often cycle right back up without problem at all. 

Increasing Just to Increase is Not Necessary

It is important to recognize that everyone has a place where adding mileage leads to breakdown. Think about it. You cannot add on 10% forever, can you?

Sure, there are elite runners who run for a living and they can cycle through 100+ mile weeks like it’s their job. That is because.. well, it’s their job. 

Even elites have a top number where an injury is more likely to occur if they push through it. When you hit a point where you feel like you are slogging through the miles, struggling to do the work you once could easily do, it might be the top end of your comfort zone for weekly mileage. 

A running friend was routinely running 50-55 miles a week. She held there for months. When she tried to increase it to 60, she did great for a week or two, then her body would get angry. According to the 10% rule, she should have been able to add those miles. 

Do you know what she found? Her body performed best when she stayed at 50 or so. This is also when she could get the best quality out of her workouts. Quality trumps quantity folks. Increasing just to increase is not necessary. 

When to Ignore the 10% Rule

When is it safe to ignore the 10-percent rule? 

• • 1. If you are a veteran runner and you know you are running below your baseline. 
    2. If you are in deep training, running high miles, and at the high end of what you know your body can handle. (Then you need to increase by less than 10%, or not at all!)
    3. New to running but with a good cardiovascular base and no problems with time on feet. Then you can increase faster. 
    4. New to running and struggling to get into shape. Then you should take it slower!
    5. You are coming back from an injury and a specialist gave you specific instructions to take it slowly. 

The 10-percent rule is an excellent one because it gives good advice for people needing it. Left to their own devices, many runners would keep adding miles. This can lead to injury and let’s face it, no one wants that. 

Just like any piece of advice, what works for some does not work for others. The key, as always, is to run smart and listen to your body. 

To read more about training for increased distances, read our article titled How To Train For Long Distance Running: A Guide For Real People