One phrase runners do not like to hear is “you have to rest in order for your injury to heal.” A stress fracture, a small break in the bone caused by repetitive stress, is a dreaded injury that sidelines a runner and really does require rest to properly heal. I find that this time of year is when stress fractures start popping up among the adult running population. The weather has been nice for a couple of months and many have increased their running since the winter. Many people have trained for and run a spring marathon or half marathon. The summer race calendar is full of 5ks and 10ks and many continue to train for fall races. If rest and recovery have not been sufficient through all of these miles, a stress fracture can occur.
What is actually happening to the bone with a stress fracture? There is an outer layer of connective tissue on bones called the periosteum. The periosteum contains nerves and blood vessels that nourish the underlying bone. It also serves as an attachment for muscles and tendons on the bone. The periosteum can become inflamed through repetitive stress (shock absorption or through the pulling of the tendons that attach to it) and cause what is called a “stress reaction.” During this stage, the bone structure is becoming compromised. If it is caught and treated properly, you can stop the damage at the stress reaction and the body will repair itself. If left untreated (i.e. you keep running through the pain), the periosteum will break down and eventually the bone itself will become affected. This is when the stress reaction progresses to a stress fracture.
Stress fractures can occur in most bones in the body. The most common sites for runners to develop stress fractures are the tibia, femur, and metatarsals (foot bones). Pain from a stress fracture is often felt during activity, but as it progresses, pain can be felt even after prolonged periods of rest. Pain is usually localized to a specific area and can present as a dull ache or a sharp pain. Swelling may be present but isn’t in all cases.
What causes a stress fracture? There are many biomechanical, internal, and external factors that can contribute to a stress fracture. It is difficult to point the finger at one as the reason for the fracture. If you are experiencing pain that you think might be a stress reaction or fracture, you should consult a healthcare professional that will help you address the following factors that can be contributing to your pain:
- Training progression – have you done too much, too soon? A proper progression of running should be followed, no matter if you are training for your first 5k or your 5th marathon. Stressing the body before it is ready will result in injury. Cross training and rest should be incorporated into your program to allow the body to properly repair itself.
- Flexibility – tight muscles can affect the biomechanics of running gait, causing increased forces in certain areas of the body. For example, if the calf muscle it tight, it will cause the heel to lift up off of the ground early, shifting the forces forward towards the metatarsal bones. Incorporating regular massage (either self-massage with tools like foam rollers, Addaday sticks, or balls, or a regular visit to a massage therapist) into your routine will help keep the muscles mobile and the joints moving freely. Regular stretching and activities like yoga can help to counteract the muscle tightness that results from repetitive motions like running.
- Muscle mass – muscles play a large role in the absorption of shock. The more shock a muscle absorbs, the less shock the bone has to absorb. There is research to support that a decreased circumference of the calf muscle contributes to tibial stress fractures. Increasing the size and strength of the calf can help to prevent tibial stress fractures. This same theory can be applied to the quads, hamstrings, and hip muscles to help protect the femur.
- Nutrition – a lack of Calcium and Vitamin D can contribute to the bone’s inability to repair itself properly
- Underlying medical conditions – conditions like osteoporosis or osteopenia should be ruled out as well as other hormonal imbalances that can contribute to stress fractures or the bone’s inability to absorb vital minerals.
- Shoe replacement – recent studies show that aged running shoes cause lower extremity muscles to activate sooner to help absorb shock, which increases the amount of muscle vibration and fatigue. The same study also shows that aged midsoles of running shoes cause an increase in vertical ground reaction force loading rate, which has been associated with stress fractures. You should try to replace your running shoes every 300 – 500 miles. As a general guideline, regardless of how much you’re running, you don’t want to go too much over a year without replacing your shoes. The material that many shoe midsoles are made of breaks down over time, even without wear. So the older a shoe is, the less efficient it will be at providing cushion and shock absorption.
What happens if you develop a stress fracture? Recovery from a stress fracture can vary based on how long you had the symptoms before you were diagnosed, how much rest time you took before diagnosis, the severity of the fracture, and the location of the fracture. Some people might be required to wear a walking boot or use crutches while others are just instructed to go about their daily activities, but avoid activity that causes pain. Typical healing time is anywhere between 6 – 12 weeks. As a note of caution, regular x-rays often do not reveal stress fractures in the early stages. If your x-ray is negative but you are still experiencing pain, make sure you follow up with your doctor.
Return to running? Remember that one of the contributing factors to stress fractures is improper progression of running. Doing too much, too soon after a stress fracture will cause the pain to start up again and can jump start a stress reaction. Realize that after 6 – 12 weeks, you will not be at the same fitness level that you were pre-injury and your body will not be able to tolerate the distances and paces that you were running before the injury. Start short and slow and always take a day rest between runs. Regardless of your pre-injury level, a run/ walk progression is the best way to safely increase distances without stressing the body too much. Let pain be your guide. If it hurts, stop. If you are sore the next day, you did too much. Adjust your workout accordingly and try again when the pain has subsided.
With so many factors involved in stress fractures, it can be daunting to think of everything and make sure you are doing all of the right things! Be aware of how your body is feeling after your runs. If you have persistent pain every time you run, or pain that doesn’t do away when you run, see someone about it sooner rather than later. Catching that stress reaction early can be the difference between continuing your running through the summer and fall or walking around in a boot for a few weeks!