Just like any other tissue in our body, bones adapt to stresses that we put them trough. When we walk, run or jump, forces that go through your body can be as high as 12 times your body weight. That is a lot of pressure on your bones! For bones to be able to absorb that much weight, they need to get stronger. However, contrary to muscles for example, bones take much longer to adapt.
Whenever you do any physical activity, your bones undergo microscopic damage. When you sleep and eat properly, the body can heal this microscopic damage and make bones stronger over time. However, if you train too much and do not eat/sleep properly, your body is not able to keep up with these accumulated stresses, and bones become weaker. Eventually,bones get so weak that this leads to a fracture - a small crack within the bones.
Individuals who acquire stress fracture often describe a localized discomfort somewhere along the bone. Many individuals will have an excruciating pain upon palpating the tender spot. This discomfort gets worse with more physical activity until it reaches a point where any weight bearing causes pain.
Compared to any other sport, stress fractures are most common in running and they tend to occur most frequently in shin bones (tibia and fibula), followed by thigh bone (femur) and foot bones (metatarsal and navicular bone).
WHAT CAUSED MY STRESS FRACTURE?
Stress fractures occur when there is a mismatch between the recovery processes and the amount of stress you are putting your bones through. In other words,too much training and too little rest. This often happens, when you start to run or jump much more than what you are used to. Your body cannot fully heal bones for the next training session, so bones become weaker and weaker until you realize that you have a stress fracture.
With runners, this increased stress might come from a switch to a barefoot or minimalist shoe running and/or switching to harder surfaces like concrete. The body is not used to these increased impact forces, so bones are not able to adapt in time to properly resists and adapt.
Another overlooked issue among runners is the role of strength in the prevention of stress fractures. Did you know that researchers from Australia have found that for every 10 mm reduction in calf circumference there is a fourfold increased incidence of shin stress fractures? Similar findings have been found for thigh, shin, and foot bones. What this tells us is that muscle strength plays a huge role in absorbing impact forces when running and jumping and thereby protecting bones from bending and fracturing.
GETTING BACK TO RUNNING
Depending on the severity of a fracture, it might take at least 6-12 weeks of no running and being in a boot or on crutches. It is important to have patience and not to push through pain since this will only make the issue worse.
During this time it is highly recommended to get involved in cross training. Engaging in strength training, riding a stationary bike and swimming can help you maintain fitness and even improve your physical fitness. Getting muscles strong will protect the bones and reduce the risk of future stress fractures.
Besides reducing the risk of many injuries, strength training has been shown to have many benefits on performance and health. Getting involved in progressives strength training is one of the most important things you should start doing in case you are serious about your training and health.
Once the pain from a stress fracture is gone, start first by walking and slowly implementing short, low intensity runs. Over time, increase running intensity and distance, while being mindful of any possible discomfort.