If you have read the “about” on the runwithgina.com website or read my very first blog post, then you know that I sustained preventable stress fractures in both feet when training for my first marathon. Stress fractures are the result of both intrinsic and extrinsic factors. It is the intrinsic factors that I find interesting as a female runner and both factors interesting as a coach. Everyone should be made aware of what contributes to stress fractures in general, especially for parents of younger children that seem to be growing up in a time of more sedentary lifestyles vs my generation that was outside running and jumping, playing hop scotch, jumping rope, red rover, hide and seek, and kick the can, in addition to organized sports.
According to research, it is difficult to determine risk assessment for stress fractures because there are so many interrelated variables. Regardless, I feel like I, personally, have combed through the evidenced-based literature looking for the answers as to why I got stress fractures in both feet and more importantly, moving forward, looking for how I can make the safest recommendations to those that allow me to work with them or even those that just tune into my blog. The above is the fuel driving the current blog post.
The most common site of stress fractures amongst running athletes are sustained in the tibia, navicular, and fifth metatarsal (Shindle et al., 2012). One clear cut risk factor for stress fractures is being female. It has been noted that females are 1.5-3.5 times more likely to sustain a stress fracture than males (Scofield & Hecht, 2012). This alone is due to multiple factors including, but not limited to, female athlete triad; low energy availability (not eating enough calories to support the energy expenditure), amenorrhea (absence of menstrual cycle), and low bone mineral density as seen in younger, competitive female endurance athletes as well as any female athlete whose sport fosters an environment of leanness or low body weight (keep that in mind, parents of young dancers and gymnasts). Although sports like running, dancing, and gymnastics have a bone bearing affect to them, which should strengthen bone, it is the lack of energy (calories) and female hormones associated with menstruating that create the lower bone mineral density, more susceptible to fracture in puberty age girls and young women.
Otherwise, running, jumping, and hoping are excellent for bone health. Bone mineral density previously mentioned is a measure of bone mass. The unfortunate thing is that according to research, peak bone mineral density is acquired during pre-adolescence and peak bone mass has likely occurred by the second decade of life through bone bearing exercise in childhood (Scofield & Hecht, 2012). Think for one moment, how this might impact my fellow runners that take up running later in life but were inactive in their youth? Moving forward, how might this impact the young people of today that were born into the screen-time generation, where playing hours of video games and hours of watching YouTube/movies/television is the norm, as opposed to activities that include bone bearing? Just some food for thought folks, and another reason why the Run With Gina blog posts are applicable to multiple populations, so don’t forget to share with your friends!
So, what about my stress fractures? They were in fact in the navicular bone of both feet, which were identified above as a common site of fracture in running athletes. The navicular bone, is the main insertion point of the posterior tibialis muscles, which creates the motion of inversion at the foot, but also resists the movement of eversion (think pronation) at the foot. Stress fracture occurrence has a high association with rearfoot eversion/pronation in the stance phase of running as perpetuated by an altered load distribution from tibial internal rotation (Milner et al., 2010). Ah ha! I feel like I’m a detective following a lead here. My posterior tibialis was not strong enough to resist the motion of eversion, but who is causing eversion? Why that is Mr. Peroneus Longus, of course, and he lives on the outer side of your lower leg and has a propensity to get overactive as one of the muscles of push-off during running and foot/ankle stabilization. But what structures cause internal rotation of the tibia? Believe it or not, the structures that accelerate tibial internal rotation all originate on the pelvis; medial hamstrings, sartorius, and gracilis. I know, I know those names may sound like a foreign language, but the point here is that stress fractures can occur at the foot from a motion that begins at the lumbo-pelvic-hip complex. Preventative and rehabilitative measures should focus on muscles at distant sites, not just at the site of fracture.
What I hope is even more clear to those of you that have graced me with your reading presence through all my blog posts, is that my goal is not only to help runners improve their race performance, but remain injury resistant in an activity that is plagued by injury. The latter is not easy because injury prevention is poorly understood without an understanding of functional anatomy and biomechanics which most people don’t have. Unfortunately, this also true of most coaches at every level. One cannot become a better runner when sidelined by injury and that is a no-brainer.
As far as the subject of stress fractures goes, the above is not an entire list of intrinsic factors and I didn’t even go into extrinsic factors. However, I must let it be known that one controllable extrinsic factor is the loading of mileage or how many times/miles in a week you run in relation to the weekend long run. It blows my mind to see weekend warriors -- people that run long on the weekend, but don’t run any miles on the weekdays to support it. That is just an accident waiting to happen for all kinds of issues, including stress fractures. Keep in mind, safety is no accident!
Milner, C. E., Hamil, J., & Davis, I. S. (2010). Distinct hip and rearfoot kinematics in female runners with a history of tibial stress fracture. Journal of Orthopaedic & Sports Physical Therapy, 40(2), 59-66.
Scofield, K. L., & Hecht, S. (2012). Bone health in endurance athletes: Runners, cyclists, and swimmers. Current Sports Medicine Reports, 11(6): 328-34.
Shindle, M. K., Endo, Y., Warren, R. F., Lane, J. M., Helfet, D. L., Schwartz, E. N., & Ellis, S. J. (2012). Stress fractures about the tibia, foot, and ankle. Journal of American Academy of Orthoapaedic Surgeons, 20, 167-176.