MANY RUNNERS are familiar with the 10 percent rule of increasing mileage. It states that increasing your mileage by more than 10 percent from one week to the next will increase your chance of injury.
Various scientists and coaches have disputed the rule over time. New research published in the Journal of Orthopaedic & Sports Physical Therapy also supports scrapping the rule, while providing insight on how great an increase is safe, and what injuries are most likely when runners ramp up their mileage too quickly.
Danish researchers followed the training of 873 healthy novice runners for one year. During that time, 202 of them suffered a running injury, which the researchers defined as “any musculoskeletal complaint of the lower extremity or back caused by running that restricted the amount of running (distance, duration, pace, or frequency) for at least 1 week.”
The researchers put the runners in three groups: those who increased their mileage by less than 10 percent per week; those who increased their mileage by 10-30 percent per week; and those who increased their mileage by more than 30 percent per week.
Counting all injuries, there was no statistically significant difference in injury rates across the three groups.
However, the types of injury participants suffered did vary by mileage increase. Those who increased their mileage more than 30 percent per week were more likely to suffer what the researchers describe as “distance-related injuries.” In that category, they included patellofemoral pain, iliotibial band syndrome, medial tibial stress syndrome, gluteus medius injury, greater trochanteric bursitis, injury to the tensor fascia latae, and patellar tendinopathy.
“Distance-related injuries” didn’t include some common running injuries that, the researchers said, are usually associated with too-sudden increases in pace, not distance. These included Achilles tendinopathy, hamstring strains, tibial stress fractures and iliopsoas strains.
The researchers cautioned that while their findings suggest that it’s okay to be more aggressive about increasing your mileage, runners should proceed with extreme caution. They noted that just because it’s okay to increase your mileage 25 percent from one week to the next, continuing to do so over a four-week period could lead to injury.
