The Stress of Stress Fractures
For many of us running is a form of stress relief, a way to unwind and forget about a lot of life’s hassles. So, how could it be that such a therapeutic and enjoyable pastime could cause any type of further stress on the body?
Among the most common types of overuse injuries in runners and active individuals are stress fractures. Stress fractures can occur anywhere throughout the body, but they most commonly occur in the feet and legs, with up to 95 per cent of stress fractures being related to the lower extremity. Due to the weight-bearing nature of running, runners are at an increased risk of developing lower limb stress fractures with the injury accounting for approximately 15-20 per cent of all musculoskeletal related injuries. Often an injury is not addressed until the bone stress has already started to develop beyond its recovery parameters -it may be fair to say that prevention of such injury is poorly executed throughout the running community.
Stress fractures develop due to accumulative bone stress that occurs after episodes of mechanical loading. Like all tissues during loading, microdamage occurs within the bone before it is repaired during recovery periods. Similarly to most overuse injury mechanisms, if the degree of stress and microdamage outweigh the body’s level of recovery, an injury is almost inevitable, and in this case, further bone stress develops leading to a stress fracture.
Stress fractures are rarely due to a single cause, and its development is often multifactorial. Many risk factors may predispose individuals to develop progressive bone stress, including both intrinsic and extrinsic factors. Training load tends to become the area to blame, and although it is a significant culprit, identifying any possible secondary risk factors may be necessary for more comprehensive prevention and management of stress fracture injuries.
We are taught from a young age that drinking milk will make your bones grow strong, and studies have found that higher consumption of calcium and dairy products may lead to a significantly reduced risk of development of stress fractures. Given this, including calcium-based products in your everyday diet is a great modifiable risk factor to consider. Furthermore, calcium supplements may be useful when incorporated into an athlete’s rehab/management plan.
Most commonly, high training loads and, explicitly running, may increase one’s chances of lower limb stress fractures. Athletes running greater than 32km per week have been found to be twice as likely of acquiring lower limb stress fractures. Now, I bet most of us fall into this category. One thing to keep in mind is that the body is very good at adapting to loads, pending increases are done smartly and appropriately. As always, the rule of thumb with overuse injury is that training needs to be managed so that any increase in running load is done realistically, and that sufficient recovery time between sessions is upheld.
Biomechanical characteristics may also be implicated in the development of stress fractures. Efficient running biomechanics means that the runner can produce fewer impact forces, as well as optimise the body’s ability to absorb these forces safely. Runners with higher impact forces, for example, initial peak acceleration, may, therefore, be at high risk of bone stress and more likely to develop stress fracture injuries.
When experiencing stress fracture symptoms, the athlete will most likely have local and pinpointed tenderness around the affected bone, and weight-bearing activities such as walking and running will cause pain and discomfort. Generally, the affected area will need to be immobilised with a moonboot to take any further load away from this area. Further load reduction is necessary in some instances, and the use of crutches may also be required.
Tissue healing timeframes generally occur between 4-6 weeks, depending on the severity of the injury. The athlete will need to take a break from weight-bearing activities during this time to allow healing to take place. This does not mean that all training has to come to a halt. Non-weight bearing activities such as swimming, cycling and deep-water running are great alternatives to training during this time. When looking to return to weight bearing training, it is essential to ensure a gradual return takes place, and not to rush back into pre-injury training loads.
After training recommences, it is important to note that previous history of stress fracture significantly increases one’s likelihood to develop such injuries again. Therefore, optimising bone healing and addressing all relevant factors for injury management is paramount to ensure any reoccurrences are minimised.
Wright, A. A., Taylor, B. J., Ford, R. K., Siska, L., & Smoliga, M. J. (2015). Risk Factors Associated With Lower Extremity Stress Fractures In Runners: A Systematic Review With Meta-analysis. Brittish Journal of Sports Medicine, 1517-1523.