Why do runners get stress fractures?

According to a 1996 review in Sports Medicine, stress fractures “result from repetitive, cyclic loading of bone which overwhelms the reparative ability of the skeletal system.” Stress fractures can occur from either increasing the load on the bone (e.g. adding speedwork, switching from trail running to sidewalks, or wearing less supportive shoes), or from increasing the number of times the bone is stressed (i.e. increasing your mileage). Running causes more stress fractures than any other sport because we tend to run on hard surfaces and land with forces of 4 to 6 times bodyweight.

The impact forces of running make our bones stronger, however, our bones can only adapt at a gradual rate. That is why you may get a stress fracture from increasing your mileage too quickly from 20 to 40 miles per week, but a few years later may handle 60 miles per week with no problems.


Related articles:
Retuning to running after stress fracture or other major injury

Running and its Impact!
Preparing your legs for 26.2 miles of hard road

Text copyright © by Pete Pfitzinger
Pete Pfitzinger is an exercise physiologist with over 20 years of coaching experience, Pete adheres to the principle that every runner is unique and that training programs must be tailored to the athlete's individual strengths and weaknesses. 

Pete Pfitzinger is co-author of two successful books:

Road Racing for Serious Runners
Road Racing for Serious Runners
Buy it here

Advanced Marathoning
Advanced Marathoning
Buy it here

This article has informational purpose and  isn't a substitute for professional advice.

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