Propelling your body through space requires a complex interplay of your major muscles. The gluteus maximus, gluteus medius, gastrocnemius, soleus, and vasti create acceleration, according to an August 2010 paper in the "Annual Review of Biomedical Engineering." The contribution of the abductor and adductor muscles remains unclear. An August 2007 report in "Medicine and Science in Sports and Exercise" indicated that these muscles often show imbalance and injury in athletes. This finding suggests that the hip muscles play a greater role in running than previously thought.
Hip Muscles Control Running Speed
The abductor muscles in your hips move your legs away from your body. The adductor muscles move your legs together. These muscles work in combination to allow runners to accelerate, according to a November 1986 report in the “American Journal of Sports Medicine.” Exercising can increase the strength of these muscles and reduce the potential for injuries. Such training -- if done properly -- increases your running speed, according to a September 1997 paper in “Sports Medicine.” It remains important, however, to keep your left and right side equally strong to avoid a muscle imbalance.
Weak Abductors Increase Injury Risk
Knee injuries have become the most common ailment for runners. Athletes with an improper stride often place excess pressure on the knee abductors, according to a review by the American Academy of Podiatric Sports Medicine. The role of the hip abductors in improper striding remains unclear. An October 2011 report published in the "Journal of Applied Biomechanics" explored the possible contribution of the hip muscles to running injuries. The authors evaluated runners known to have excess varus excursion -- an improper gait that places too much pressure on the knees. Three-dimensional video scans revealed that such athletes underuse their hip abductors. This finding suggests that strengthening the abductor muscles could reduce the risk of knee injuries.
Strong Abductors Decrease Injury Risk
Many types of exercise can increase the strength of your abductors. Using your hip muscles to repeatedly pull an elastic band enhances hip power, according to a November 2010 paper in the Polish journal "OTR." This type of isometric exercise with resistance has become increasingly popular, and the required elastic bands have become readily available. It remains unknown, however, whether these exercises actually reduce the stress placed on the knees. A study described in the January 2009 issue of "Clinical Biomechanics" explored this possibility in healthy women. The participants regularly exercised for six weeks. This protocol caused a 13 percent increase in the strength of the subjects' abductors. It also caused a 10 percent decrease in the pressure placed on their knees during running.
Adductor Pathology Increases Injury Risk
The strength of most muscles declines with advancing age. A March 2011 article in “Gait and Posture” evaluated this relationship for hip adductors. Younger and older women ran test sprints during a single testing session. Older women had more instances of adductor pathology than younger women, but no subject had an actual injury. It remains unclear, therefore, whether having such a pathology increases your risk of injury. An investigation presented in the January 2005 edition of the “Clinical Journal of Sport Medicine” tested this hypothesis in recreational runners. The researchers compared the hip muscles of injured and healthy runners. Athletes with injuries had more asymmetries than those without injuries. For example, having one adductor become stronger than the other increased injury risk.