The 10% Rule: Is It a Valid Way to Increase Your Weekly Running Mileage?

In the running world, the 10% rule is pretty much akin to the Golden Rule. It states to never increase your mileage by more than 10% in a week. 

The trouble with the 10% rule is, it’s not based on scientific data and is not appropriate for all runners. Runners come from all different backgrounds and experiences, and so there is hardly ever a one-size-fits-all-approach. 

Last year, when I was coming back from a hamstring injury, I became attached to increasing my mileage by 10% every week. However, I kept having setbacks. Why? Because I ignored other considerations such as cutback weeks and the time it took for my tendon to strengthen. The 10% rule did not apply to me. 

Conversely, other runners coming back from other types of layoffs can start back faster whereas new runners may need to increase volume more slowly than 10% a week.

This article will ensure you don’t fall into the trap of ramping up too quickly or decreasing mileage too slowly by helping you set a starting point and increase your volume based on your own experience and background.

In this article, we’ll go through:

• what is the 10% rule

• the validity of the 10% rule (does it really work?)

• alternative (and better) ways to increase mileage

• how to start increasing mileage

• other considerations for increasing mileage

• how runners should increase mileage when introducing new stimuli like hills or speed

What is the 10% rule?

The 10% rule simply states that when increasing mileage, you should never increase mileage more than 10% at a time in a week. 

Thus, if you’re running 20 miles, you should increase to 22 miles the following week, 24.5 miles the next week, and so on. 

The purpose behind the 10% rule is to ensure runners increase their mileage conservatively. 

“The rule is based in building your mileage slowly as to decrease you risk of injuries and because of this, yes, there’s merit in being conservative and safe at times,” explains Steve Stonehouse, certified running coach and director of education for STRIDE, a treadmill studio franchise. 

However, it does not apply to everyone.

So Just How Valid Is The 10% Rule?

Certified running coach Laura Norris says the 10% rule is arbitrary. 

“That is not to say that it does not work; it will work fine for many runners.

However, there is no solid evidence to support it.

Many runners can still get injured under the 10% rule, since it does not account for adaptation cycles or cutback weeks,” she explains. (I can vouch for that).

For example, a study on bone restructuring in response to high-impact exercise suggests that increasing mileage by 10% every week can make bones weaker for about a month after a new stress, while they resorb tissue and remodel the bone structure. Therefore, it makes sense to wait about a month before increasing training volume.

10% Rule Alternatives – Are there better ways to increase mileage?

That is what legendary running coach Jack Daniels suggests.

Daniels advocates for increasing mileage based on the “equilibrium” rule. This involves increasing mileage in larger chunks to account for the bone adaptation:

Instead of increasing volume week over week, you would increase about 30% every 3-4 weeks. The result is about the same volume as if you increased by 10% every week.

Thus, if you are running 20 miles a week, you would increase to about 30 miles the following 3 to 4 weeks. With the 10% rule, in 3 to 4 weeks, you would also arrive at about 30 miles in a month.

By increasing mileage in bigger chunks every few weeks, you get about the same volume while accounting for skeletal adaptations. 

Related: How to Train for a Marathon in 3 Months

How to start increasing mileage?

When charting your path to increasing mileage, runners should first pinpoint their baseline mileage which is the mileage you feel comfortable increasing from. 

“Most of your training cycles should start slightly under this baseline to ensure you’re starting at a realistic workload. When you’re building up to your baseline, the miles are still very comfortable at this point so you can increase your mileage more quickly than 10% per week,” advises Stonehouse.

Instead, you can safely add 15-20% more per week – at least initially. 

With that said, as soon as you get above your baseline mileage, it’s helpful to be more conservative. Rather than adding 10% per week, sometimes it’s best to add 5-10% every other week.

Beginner runners should begin and increase training based on time. 

“In the early stages, it’s just about getting your body used to the work and building some aerobic capacity (endurance),” said Stonehouse. 

After 1-2 months, beginner runners can start logging miles and increasing accordingly.

What are other considerations for increasing mileage?

When increasing mileage, it’s important to include cutback weeks about every month.

“On these weeks, you’ll reduce your mileage to about two-thirds of the previous weeks’ mileage,” explains Stonehouse. “A good way to do this is to training plan your training in 3-5 week cycles, using the first 2-4 weeks to push the training and introduce the stress, and then use the final week of the cycle as a recovery week to absorb the training just done, make the necessary adaptations, and recover so you can handle the upcoming heavier training load.”

Stonehouse also likes to repeat training weeks for runners who have built up to their baseline mileage to allow the body to adjust to increasing mileage, intensity and duration of quality workouts. 

“I find it’s helpful for all runners but specifically those who are prone to injuries or beginners who need extra time to recover from and adapt to their workouts,” he shares. “After you surpass your baseline mileage and you don’t feel comfortable, it’s more helpful to implement these repeats.”

How should I increase mileage based on experience or injury history?

Norris explains, if an experienced runner is rebuilding to a previous mileage after a post-race recovery, they do not need to follow the 10% rule. Instead, they can increase more rapidly until they are back at their baseline mileage, almost like a reverse taper. 

The same applies for an injured athlete; after full recovery, they may only need six to eight weeks to safely return to their previous mileage.

If a beginner runner is building to a new mileage, a better system is an increase-adapt pattern, with consistent cutback weeks every four to six weeks. 

Beginners can increase up to 15-20%, depending on mileage (higher mileage runners increase a lower percentage per week; lower mileage can increase a higher percentage per week). This allows the musculoskeletal system to better adapt to the demands of increased mileage, says Norris. 

Example for building mileage:

Here is an example for a runner building from baseline of 30 miles per week to 40 miles per week:

– Week 1: 30 miles

– Week 2: 34 miles

– Week 3: 34 miles (repeat week)

– Week 4: 38 miles

– Week 5: 30 miles (cutback week)

– Week 6: 38 miles

– Week 7: 40 miles

Related: Check out my Marathon Training Plans

How should I increase mileage when introducing new stimuli like hills or speed?

When introducing new stimuli like speed, duration of quality workouts, or hills, for the first time, or the first time in a long time, it’s important to not increase mileage at the same time. 

“You want to maintain your mileage for a few weeks as your body adapts. For injury-prone runners or fast-twitch runners who fatigue easily with higher mileage, the better choice may even be to temporarily decrease mileage while introducing a new stimuli,” suggests Norris.

Related: How to Run Downhill Correctly

Stonehouse reminds runners of what is the only rule in running that truly applies to every runner: when increasing mileage, “run easy on easy days to truly recover and hard on hard days to provide stress.”

When you give recovery the same amount of attention as running, your workouts will flourish and you’ll be a better, stronger runner than ever.