Runners Who “Run the Risk of Injury”

Running has become a popular form of exercise for both women and men because it is beneficial to their health, requires no training, and can be accomplished without equipment (unless addicted to an indoor treadmill). Unfortunately, something so natural comes with a high rate of injury, as high as 37-79% yearly for the typical runner. Health care providers have tried to identify an accurate set of predictive risk factors for running injuries, but with little success. Most say that age, gender, height, weight, and running experience are not related to running injuries, with the exception of more stress fractures in female runners (sorry, ladies). Several studies have investigated differences in anatomic alignment between injury-free runners and those prone to overuse injuries, also without concrete conclusions on why injuries occur in some and not others. And then some researchers consider all running injuries as “overuse” or training error problems resulting from too many miles, too fast a pace, or running on the wrong surface. If all running injuries result from training error, then all injuries could be prevented. That’s a good thing. All of these arguments deserve some attention.
First, let’s define “overuse injury.” An overuse injury is an injury of the musculoskeletal system resulting from the combined fatigue effect over a period of time beyond the capabilities of a specific anatomical structure that has been stressed. When repetitive forces, such as the impact experienced during running, are applied repeatedly to a muscle, tendon, or bone, injury can occur if sufficient rest between stresses does not occur. Specifically, a running overuse injury can be defined as a musculoskeletal ailment attributed to running that causes a restriction of running speed, distance, duration, or frequency for a least one week.
Half of running injuries occur in the knee. The most common knee complaints in runners are patella femoral pain syndrome (pain near the knee cap), iliotibial band friction syndrome (pain on the side of the knee), meniscal injuries and patellar tendinitis (pain in or under the knee joint). Achilles tendinitis and shin splints account for 40% of running injuries. The fact that 90% of running injuries occur at or below the knee suggests a pattern that can be identified and predictive of overuse injuries if researchers keep looking.
Training variables that are linked in to running injury in some, though not all, studies include running distance, training intensity (speed), rapid increases in weekly running distance or intensity, and stretching habits. Increasing running distance or speed too aggressively can lead to structure damage (inflammation, strain, sprain, tearing) if some other variable of the workout is not adjusted. If distance is increased, then speed or amount of incline could be decreased to avoid injury. Gradual increases make sense! Some studies relate stretching prior to running with injury prevention, especially stretching posterior thigh (hamstring) muscles. Achilles (heel cord) stretching prior to running is not a sure protective measure, but a few studies do link normal foot and ankle motion with fewer foot injuries. The message here is to stretch prior to running if it has helped you in the past, but there is no research support yet for guaranteed injury protection from stretching before running.
Another controversial area in overuse running injuries is anatomical alignment in the lower extremities. Investigators have found strong links, weak links, and no links between injury and high arches, flat arches, leg length discrepancies, hip and knee angles of alignment, and rear-foot alignment angle. Some research does identify women at greater risk for injury due to hip and knee alignment, and that may be something to consider if the female runner has excessively “bowed legs” or has “knocked knees.” A more important biomechanical factor seems to be the amount of time it takes for the foot to roll to the medial side (pronate) when in contact with the ground which, if excessive, can increase vertical forces through the foot, ankle, and knee and result in shin splints, knee pain or even stress fractures.
One variable that can be influenced by the runner is hip strength. Studies have found that weakness in the gluteus medius muscle (the muscle that moves your leg out to the side) can increase stress on the leg while running, and is found in runners with iliotibial band syndrome. A 6-week strengthening program for the gluteus medius resulted in 35-50% improvement in strength and resolution of pain while running in adults with iliotibial band syndrome. This is a factor that runners can influence through a cross training program that includes a strengthening component, not just running in isolation.
Do you run the risk for running injury? It is hard to say, but listen to your body and be smart about running progression; stretch if it makes running more comfortable; and strengthen weak hip muscles if indicated. Consult a health care provider if you believe alignment problems may be impacting your risk for running injuries
References:
Wen DY. 2007. Risk factors for overuse injuries in runners. Curr Sports Med Rep, 6:307-313.
Hreljac A, Ferber R. 2006. A biomechanical perspective of predicting injury risk in running. International SportMed Journal, 7(2):98-108.
Hreljac A, Marshall RN, Hume PA. 2000. Evaluation of lower extremity overuse injury potential in runners, Med Sci Sport Exerc, 32(9):1635-1641.