Stress fractures occur when repetitive stresses are applied to a weakened bone. This is a chronic injury, which means that it does not happen from a one-time event, but over an extended period. Improper equipment (worn or improper shoes), muscle imbalances, or improper running and walking gait can all cause stress fractures.
The muscles are designed to act as shock absorbers during impact activities. They take the stress off the skeletal system and the internal organs. When the muscles become fatigued due to a workload that is more than they can handle they will no longer be able to work as shock absorbers. The load is then transferred to the bones. The force is transferred through the bone until it reaches a weak area where it causes a small crack. Over time, that develops into a stress fracture. This process is known as the fatigue theory.
When the human body is subjected to a slight increase in workload it will adapt by getting stronger. The bones, tendons and muscles will all change to handle the increase. If the workload is increased too quickly the body is unable to adapt quick enough and the stress is transferred to the foundation of the body (the skeletal system.) If there is a weakness in any part of the skeletal system this increase in stress will cause it to succumb to the pressure and crack. This process is known as the overload theory.
Symptoms of stress fractures are fairly focused. Pain usually increases with weight bearing activities and diminishes with rest. Pain is most severe at the beginning of the activity then subsides in the middle of the activity and increases in severity near the end. The pain continues as a dull throb after the activity. Swelling and point tenderness around the site of the fracture may also occur. The pain will gradually get worse and may occur earlier in the workout over time. If left untreated the pain may become unbearable.
Prevention and Treatment
Due to the extended recovery time (6-10 weeks), preventing stress fractures is of major importance. Gradually increasing workloads at a rate of no more than 10% a week and varying the training by using cross training techniques will help to off set the overload and repetition often associated with stress fractures.
Warming up properly and preparing the body for the workout will help to keep the muscles from fatiguing as quickly. This will also prevent injuries to the muscles and tendons, which could lead to further weakening of the bones. Injuries to the muscles, tendons or ligaments that support the skeletal system could lead to excess, and awkward, pressure on the bones.
Flexibility is essential as well. Muscles that are flexible will provide more support and, due to their elasticity, absorb more shock. They are also less susceptible to injury, which could lead to an imbalance or improper gait. Stiff muscles will also lead to incorrect running and landing patterns that could lead to extra stress.
Stretching is one of the most under-utilized techniques for improving athletic performance, preventing sports injury and properly rehabilitating sprain and strain injury. Don’t make the mistake of thinking that something as simple as stretching won’t be effective.
Using proper conditioning strategies before starting a new activity or beginning competition will also help. Strengthening the muscles (especially those in the legs) will keep them from fatiguing too early and allow them to effectively absorb the shock of the activity. Strength training will also help to strengthen the bones. Stronger muscles will support the body and help maintain proper form during running and jumping activities.
Nutrition is another important preventative measure for stress fractures. Increased nutritional intake of calcium and vitamin D will assist in bone growth and regeneration, which is vital to preventing stress fractures.
Rest is the first step in treating a stress fracture. Stopping the activity that has caused the injury and resting the injured area is essential. Ice and elevation are also important in short-term treatment. Over the counter non-steroidal anti-inflammatory medicines will help as well.
For minor stress fractures simply resting and avoiding the offending activity until pain is eliminated may take care of it. However, if the pain returns after re-starting the activity it may be necessary to see a medical professional.
Another helpful method for improved recovery is the use of ultrasound and heat. Ultrasound, or TENS (Transcutaneous Electrical Nerve Stimulation) simply uses a light electrical pulse to stimulate the affected area. While heat, in the form of a ray lamp or hot water bottle, is very effective in stimulating the damaged tissues.
Some stress fractures require immobilization or reduction of weight bearing stress. An air cast, immobilizing boot, or even crutches may be required.
It is important to keep active during the stress fracture rest period with no-impact activities such as swimming, biking or weight training. This will make the return to activity less painful.
When it is time to return to activity, usually 4-8 weeks after the injury, it is important to work back gradually and identify the error that originally caused the injury and avoid the same mistakes.