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$1.05 million grant:UD professor to study women runners in hopes of eliminating stress fractures

NEWARK, DE.--Four hundred college age women may literally be running toward better health as they participate in a University of Delaware study on the causes of stress fractures in runners. The study aims to someday make the common but serious injury avoidable.

With the hope of preventing stress fractures in military recruits and civilian athletes, the Department of the Army has awarded UD biomechanist and physical therapist Irene McClay $1.05 million to track 400 female runners throughout a five-year study, conducted in conjunction with the University of Massachusetts.

McClay will study the biomechanical factors associated with the causes of stress fractures in runners to determine whether mechanics change as a result of such injuries. Women runners will be studied because of they are reported to be at greater risk for the injury.

McClay, who has been with UD since 1989, said the study is needed because running is such a popular form of exercise.

"Running," she said, "has become one of the most popular forms of exercise in the United States. But, one of the consequences of this fitness is an increased risk for injury," she said. Several studies have looked into the causes of stress fractures in runners, but their etiology is still not well understood. McClay believes they are a result of some combination of structure, mechanics and training.

Incidence rates for fractures of this nature have been noted between five and 15 percent, depending on the definition of injury and study population, she added.

"One benefit of this study is that it will be prospective rather than retrospective," McClay said. "Once the factors associated with tibial stress fractures are identified, intervention strategies to minimize these risks can be developed. Studying runners both before and after injuries will allow us to assess whether mechanics are altered as a result of injury."

Stress fractures are among the more serious injuries that runners can sustain. "The fractures often take long to heal and necessitate total removal of the stress that precipitated the fracture," she said.

There are a number of theories surrounding the development of these fractures. The most current thought is that stress fractures are at the end of a continuum of bony injury that may begin with the clinical diagnosis of acute shin splints, progressing to stress reaction and finally fracture.

According to studies, women are reported to be at greater risk, and the tibia is the most common site of stress fractures in runners, accounting for between 30 and 50 percent of total stress fractures reported. McClay said she chose to study only women because of the greater occurrence of stress fractures in females.

"We plan on tracking college-age female athletes," she said. "These women are running on a regular basis and for a considerable distance. They will act as the best sampling for our study — our best chance of seeing the occurrence of stress fractures."

The research for the study, which begins in April, also will be collected at the University of Massachusetts. The 400 runners will be assessed and followed for a minimum of two years at each site.

"We needed to sample a large number of women to insure enough fractures based on a 10 percent of incidence," McClay said. "UMass, which has similar facilities, will help to collect and analyze the data."

For each runner in the study, three-dimensional mechanics will be collected with high-speed video cameras and a force plate along with structural data of their lower extremities to include both clinical and radiological measures. Then, the runners will keep a log of their progress online. All injuries will be recorded, and participants who sustain a tibial stress fracture will return to the laboratory for a follow-up assessment.

McClay hypothesized that there are several factors contributing to injuries in runners. Poor alignment, bone geometry, lower extremity stiffness and excessive loading rates could be important keys to a runner's susceptibility for injury.

"Eventually," she said, "we hope to train people how to run correctly and to change their gait pattern if necessary.

"We have had preliminary success in retraining gait and decreasing injury by training runners on a treadmill, using simply a mirror for feedback."

McClay said her biomechanics laboratory in McKinley Laboratory soon will be equipped with real time computing capabilities. Runners will be provided immediate feedback in a graphical format on a view monitor, regarding features of their mechanics that are believed to be contributing to their injury.

"Soon we will be able to watch someone's mechanics and tell them to alter their habits while they are in motion," she said. "They will be able to feel the difference immediately and learn to do it on their own. But, more studies are needed to determine optimal feedback strategies for maintaining gait changes."

McClay, who earned her Ph.D. from Penn State University, is the director of research for the Joyner Sportsmedicine Institute and the director of the Running Injury Clinic at UD.

Contact: Laura Overturf, (302) 831-1418,
March 22, 2000