Release Date: April 12, 2003
BUFFALO, N.Y. -- Competitive female runners who eat a low-fat diet place themselves at increased risk of suffering injuries, a team of researchers from the University at Buffalo has found.
Results of their study, which followed 87 women runners for a year to assess the relationship between diet and injuries, were presented today (April 12) at the Experimental Biology meeting in San Diego.
Findings showed that those who developed injuries had significantly lower consumption of total fat and percentage of calories from fat, as well as caffeine, than runners who remained injury-free. A lower total caloric intake also was useful in predicting future injury, researchers found, but there was no relationship between consumption of other nutrients and risk of injury.
"The number of women runners is increasing at a phenomenal rate, and with this comes significant health benefits, but also health risks," said Peter Horvath, Ph.D., associate professor of nutrition in the UB School of Public Health and Health Professions and senior author on the study.
"The injuries we studied were serious enough to interrupt training, to require medical visits and even result in absence from work. It's possible this research will help us develop advice for runners, potential runners and health professionals on ways to prevent these injuries."
The study group was composed of competitive women runners who trained a minimum of 20 miles-per-week and weren't injured when the study began. Participants completed questionnaires on training and medical history, reported running-related injuries during the past 12 months, and completed a 114-item food-frequency questionnaire and the Eating Attitudes Test, a tool designed to measure attitudes toward food and predict disordered-eating behavior.
Researchers measured height, weight, body fat, maximal oxygen consumption, lower extremity flexibility and alignment, ground-reaction forces (the forces produced when the foot hits the ground) and balance.
Researchers contacted participants every three months for a year following the initial assessment to gather information on their training and running-related injuries.
Results showed that 55 percent of the women reported a running injury during the follow-up year, and that injured runners consumed significantly fewer calories from fat than those without injuries.
The injuries were not related to age, miles-run-per-week, height, weight, body mass index or percent body fat. Comparisons of injured runners with non-injured runners did not show a total calorie difference, Horvath noted, but when a statistical model (multiple regression) was developed to predict injury, total calories appeared as important.
Horvath said the lower caloric intake, despite similar energy expenditure and body size of injured and non-injured runners, plus the lower caffeine intake seen in the women with injuries, hints at possible restrictive eating habits.
"This low-caffeine intake may have represented an effort by the runners to avoid foods perceived as 'bad' or 'unhealthy,' such as chocolate and soft drinks," he said. "Although mean scores on the Eating Attitudes Test for both groups were well below the point that would indicate a clinical eating disorder, several runners exhibited restrictive eating patterns.
Kristen Gerlach, a doctoral student who was the lead investigator on the research, said the restrictive eating patterns may have made the runners more susceptible to injury by decreasing the availability of nutrients used for tissue repair. Low levels of dietary fat also may have resulted in low supplies of energy, she noted, which could contribute to fatigue while running and increase the chance of injury.
"We need more studies to explore the relationship of dietary fat and injuries to separate out the issue of calories versus fat," said Gerlach. "In addition, our results on balance, ground reaction forces and flexibility have to be applied in clinical intervention studies to determine their role in predicting injury."
Other key investigators were Renee Melton, research instructor; Harold Burton, Ph.D., associate professor, and Scott White, Ph.D., associate professor, all in the Department of Nutrition and Exercise Science in the UB public health school; Joan Dorn, Ph.D., assistant professor in the Department of Social and Preventive Medicine in the UB public health school, and John Leddy, M.D., assistant professor of orthopedics, in the UB School of Medicine and Biomedical Sciences.
The study was funded in part by a grant from UB's Mark Diamond Fund to support thesis research.