Wolff’s Law dictates that a healthy bone will adapt to the loads under which it is placed.  If a bone is repeatedly stressed, over time, it will become stronger to resist forces in that direction as repetitive elastic deformation results in changes in density and volume of the trebeculae and secondary changes to the cortex.  For example, tennis players often have much stronger bones in their dominant arms, baseball players often exhibit bony retroversion on their throwing arm, and astronauts lose bone mass while in space.

As stress fractures are quite common in the distance running world, and as stress fractures are bone related injuries, it always makes sense to look at stress injury from the perspective of Wolff’s Law.  Runners exhibit cyclical loading patterns that can generally be considered as uni-directional which may leads to asymmetrical bony geometry, with the middle third of the tibia being significantly stronger than that of non-runners, while the lateral thirds were not inherently stronger (Cleek, 2005).  Similar work has been done comparing competitive rope skippers and soccer players, and it was determined that bone density was greater in both groups, with the soccer players having more symmetrical geometry (Pettersson, 2000).  As bone geometry certainly plays a role in the onset of stress fractures and frontal plane loading of the tibia during gait is greater in those with a history of tibial stress fracture, it stands to reason that symmetrical bone geometry throughout the skeletal system may help reduce the incidence of stress fractures.

How do you go about ensuring symmetrical bone geometries?  Well, you apply the principles of Wolff’s Law, of course.

Remember that bone responds to stressors by becoming stronger in the direction in which it is stressed.  This can at least partially explain why the soccer players had more symmetrical development as that sport demands that athletes function and move quickly and powerfully throughout a number of ranges of motion.

While I’d be a bit crazy to suggest that runners should be out playing soccer simply to prevent stress fractures, as professionals we’d be remiss to not include some form of multi-directional movements along with improving foot and ankle function to at least help mitigate some risk of tibial stress fracture.  Keep in mind these athletes are not generally adept at moving in frontal and transverse planes, so time should be taken to properly develop movement proficiency during which you’ll likely get some good bone modeling in the process.

In the past I’ve written a bit about using multidirectional training for avoiding pattern overload and subsequent injuries to tissues, and the same principles still apply to this case as strength and muscle CSA seem to be highly correlated with resistance to stress fractures as well.  More on that tomorrow.

Best regards,
Carson Boddicker

Boddicker Performance