Running is a repetitive motion that has a chain reaction. When a runner steps, his or her foot hits the ground applying stress that travels throughout the legs and up to the spine. With this repeated movement, if anywhere along the chain the motion is off-center, injuries may occur. Running injuries can either occur based on intrinsic factors or extrinsic factors. In order to avoid injury, it is important to understand the difference between these two factors.

Intrinsic factors relate to the body and vary among runners. Each individual has a unique running style as well as biomechanical influences. The most common place for an injury to occur is within a runner's foot. Overpronation (most commonly present in a runner with flat feet) is the leading cause for a runner's chain to be off-center. When the feet collapse inward, the legs are forced to turn in and additional stress is applied to the shins, knees, and spine. In order to prevent overpronation, stability shoes should be worn while training. If additional support is needed, orthotics may be required. Another common injury among runners occurs in the hip flexors. Developing tight hip flexors occurs when a runner has poor flexibility and his or her stride is shortened. In order to prevent tight hip flexors, stretching the hip flexor and calf muscles will drastically reduce the possibility of injury.

Extrinsic factors relate to all aspects of one's training: wearing the correct type of sneakers, conducting proper stretches prior to and after running, and eating healthy foods. All of these aid in injury prevention. The most common extrinsic factor that can prevent injury is to monitor your sneakers. If the sole appears worn out, it is time for a new pair. Remember, training in the right pair of sneakers provides cushioning and stability for your feet. Stretching is another aspect that is extremely important and often overlooked. If a runner is not flexible and the central body parts are not strong, he or she may be more prone to injury. A runner must make sure to focus on strengthening his or her core muscle groups - abdominal and gluteal - in order limit the chances of becoming injured. Finally, a runner's diet is also important. When training, a runner must eat a balance diet that consists of fresh fruit, vegetables, protein and carbohydrates. During a workout, a runner should always remain hydrated, drinking water or an electrolyte drink to replenish salt lost. Also, after completing a workout, an individual should have a lot of protein. This will allow for the individual's muscles to repair faster.

Here is a checklist for all runners that should help reduce the risk of injury:

Proper shoes - Choose a shoe that fits your specific need, whether it is motion control or stability.

Warm-up - Before going for a run, make sure to loosen your muscles. Jog for a few minutes and lightly stretch. This will activate your muscles and reduce your risk for injury during a run.

Cool-down - Stretch after a run. Your muscles will be warm and have greater flexibility. Make sure to target all of your key muscles including your hamstrings, quads, calves, IT band, and achilles tendon.

Monitor your progress - It is important to gradually increase your training, making sure never to increase your distance, frequency, or intensity more than 10% each week.

Reach a balance - Make sure that while you are training, you concentrate equally on running, stretching, and strengthening.