Bone remodeling is the process in which osteoclasts break down bone and osteoblasts build it back up (Tortora and Derrickson 2012). With increased use, the bone is made stronger. With decreased use, the bone is made weaker. For example, when bones are subjected to extended periods of time without stress they lose density. This is because the body always tries to maintain homeostasis and doesn’t want to function at a higher level than it has to. Conversely, when the bone is stressed, it becomes stronger. One of several aspects of bone remodeling is the repair of damage to bone. With each repair the bone becomes thicker and stronger at the point of damage. This damage does not always have to be a traumatic break. It can be micro trauma caused by everyday activity.
Runners are one portion of the population that relies heavily on bone remodeling to enjoy their sport. Runners put tremendous stress on their bones and muscles as they run. For some runners, they break down their bones at a faster rate than they can be repaired. When this happens, the result is a stress fracture (Lovett 2008). He lists four criteria from sports scientist Tim Noakes that are useful in deciding whether or not you have a stress fracture. “1. It comes on without warning 2. There is no other obvious explanation 3. You can sometimes find a spot on the bone so tender that pressing on it will produce a pain he describes as “exquisite” or “nauseating”; and 4. It fails the hop test, which means it hurts if you hop on the injured leg.” He lists several risk factors for stress fractures. They are, increasing training volume too much too soon, insufficient muscularity. He further elaborates saying that muscles act as shock absorbers and those with more developed muscles put less stress on their bones.
This is useful information because a surprising amount of runners have to deal with stress fractures. Knowledge is power in preventing injuries. By making sure that they maintain muscular development and not over training runners can reduce the chance of getting stress fractures.
Literature Cited:
Tortora G.J. and B. Derrickson. 2012. Principles of Anatomy and Physiology. 13th ed., John Wiley and Sons.
Lovett, R.A. “Owner’s Manual: Is it a stress fracture?” Running Times. March 2008. http://www.runningtimes.com/Article.aspx?ArticleID=12894&PageNum=&CategoryID=