Department of Family Medicine and Community Health (Drs. Sidhar and Hammer) and Department of Orthopedics and Rehabilitation (Dr. Hammer), University of Wisconsin School of Medicine and Public Health, Madison kartiksidhar@gmail.com
The authors reported no potential conflict of interest relevant to this article.
BMI.Elevated BMI increases joint contact forces, which might increase risk of pain and injury.20 Results of studies investigating the link between BMI and running injury are mixed; some report that, in regard to bone stress injury, overweight BMI (> 25) is a risk factor for male runners and underweight BMI (< 18.5) is a risk factor for female runners.4,6 An observational study concluded that, among half-marathon and marathon runners, there was no significant increase in race-related injury, based on BMI.9 However, another study showed a higher rate of running-related injury in novice runners who had a higher BMI.10 A prospective cohort study found that runners with a higher BMI reported increased knee stiffness, which can place a runner at higher risk of overuse injury.4
Although these results conflict, there is consistency in the finding that obese novice runners are likely at increased risk of running-related injury; it is reasonable, therefore, for you to discuss strategies to reduce the risk of other modifiable factors, especially among obese novice runners. Patients with a higher BMI should not be discouraged from running, because exercise in combination with healthy eating habits is essential to decrease the myriad adverse health outcomes associated with obesity.
Female runners with a lower BMI, especially in the presence of other components of the female athlete triad (inadequate nutrition, amenorrhea, and low bone density), should be counseled about their increased risk of bone stress injury.21 Notably, a study of female US Navy recruits randomized to receive a trial of dietary supplementation of vitamin D plus calcium, or placebo, showed a 21% lower incidence of bone stress injury in the active-treatment group.22 To mitigate risk of injury associated with low BMI and the female athlete triad, therefore, a multidisciplinary approach of nutrition intervention, dietary optimization of vitamin D and calcium, and, possibly, activity modification should be implemented when appropriate.
Running gait.A study using 2-dimensional gait analysis to visualize biomechanical running patterns in injured and noninjured runners found that, in regard to mechanical variables, running-related injury was most strongly associated with contralateral pelvic drop.23 Gait retraining can be employed to help decrease contralateral pelvic drop.24 In addition, pelvic drop is often a result of weak gluteal muscles, and can be improved by doing strengthening exercises at home or with physical therapy.
Longer stride is also associated with running-related injury.25 A study showed improvement in patellofemoral pain by having runners increase stride rate by 10%, which reduces stride length to a significant degree.25,26 These improvements were maintained at 1-month and 3-month follow-up, and required only 1 gait retraining session.
