Four hundred college-age women may be running toward better health as they participate in a UD study on the causes of stress fractures in runners, conducted by biomechanist and physical therapist Irene McClay.

Women runners at the University of Massachusetts also will be part of the study, funded by a $1.05 million grant from the U.S. Department of the Army.

With the hope of preventing stress fractures in military recruits and civilian athletes, the Army awarded McClay the grant to study the biomechanical factors associated with the causes of stress fractures in runners and to determine whether mechanics change is a result of such injuries.

McClay, who has been at the University since 1989, cited the popularity of running as the need for her study.

"Running," she says, "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." Several studies have looked into the causes of stress fractures in runners, but their etiology is still not well understood.

McClay says she believes they are a result of some combination of structure, mechanics and training.

Incidence rates of fractures of this nature have been noted between 5 and 15 percent, depending on the definition of injury and study population, she says.

"One benefit of this study is that it will be prospective rather than retrospective," McClay says. "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 of injuries that runners can sustain. "The fractures often take long to heal and necessitate total removal of the stress that precipitated the fracture," she says.

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, to 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 says 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 says. "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 began 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 says. "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 hypothesizes 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 says, "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 says her biomechanics laboratory in McKinly 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 injuries.

"Soon, we will be able to watch someone's mechanics and tell them to alter their habits while they are in motion," she says. "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."