The 10 Percent Rule: Fact Or Fiction?

Emphatically Debunking The 10 percent Rule

Coaches like me are always looking for scientific evidence to support our assumptions. While it’s important to be careful when extrapolating results and advice from tightly controlled experimental conditions, studies can be very useful when it comes to generalized principles. Unfortunately for proponents of the 10 percent rule, science is not on their side.

In 2007, a group of researchers set out to test the effectiveness of the 10 percent rule. The researchers studied 532 novice runners training for a local 4-mile race by assigning half of the runners to a training program that followed the 10 percent rule and the other half to a more aggressive training regimen. Each runner followed the same warmup process and the overall structure of the training was the same — minus the training volumes.

The results? The two groups had the same injury rate — about 1 in 5 runners.

Perplexed by the identical injury rates, the researchers hypothesized that the runners weren’t ready to undertake a training program when they began the study. So they repeated the study, but this time they assigned the group training under the 10 percent principle a 4-week pre-conditioning program. The control group was assigned the same, more aggressive training plan as the initial study with no 4-week buildup.

Again, the results came back with the same injury rate for both running groups, about 1 in 5.

These two studies clearly indicate that prescribing to the 10 percent rule does not reduce your chance of injury. The question now becomes: How do you decide how much can you safely increase your weekly training volume while minimizing injury risk? While the answer is certainly individual, over the following pages we’ll take a look at some more flexible “rules” to follow.

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