For a subset of women -- those with eating disorders -- exercise may have no feel-good effects. In fact, it may induce just the opposite feeling. And women in general may get less psychological benefit from exercising than men.
Those are among the conclusions presented last month by researchers Jennifer Gerlach and Dorothy Espelage at the American Psychological Association annual convention in Chicago. Gerlach, the principal researcher on the study, is a doctoral student in educational psychology at the University of Illinois at Urbana-Champaign. Espelage, the study's co-author, is a professor of educational psychology in the university's College of Education.
The study involved 324 undergraduates at Illinois, 235 women and 86 men, with an average age of 19.9 years, who were asked to complete questionnaires assessing exercise behavior, strategies for coping with stress, self-esteem, life satisfaction, positive and negative affect (similar to mood), depression, anxiety and eating behavior. The men and women were comparable in their level of exercise.
The researchers' primary goal was to determine how exercise was used as a strategy for coping with stress. But what they found in the process were curious associations between exercise and psychological health.
For the men as a group, they found statistically significant associations between exercise and almost every measure of psychological health. For the women, however, most of those associations were either weak or statistically insignificant. The researchers also found that exercise was related to both positive and negative affect, "and that didn't make sense," Gerlach said.
They hypothesized that eating disorders played a part in the contrary numbers, and so split the women into subgroups. Eleven percent were categorized as having an eating disorder, based on their responses in the questionnaires. The other 89 percent were put in a non-eating-disorders group.
For the majority group, exercise was related to positive affect, Gerlach said. "But for the women who had an eating disorder, exercise was related to negative affect, and there was a slight trend for more depression and more anxiety." For those women, "exercise isn't related to positive psychological health," she said.
One possible explanation may be that men and women exercise for different reasons, with societal pressures causing women to worry more about body image, over just feeling good or having fun, Gerlach said. Over-exercise may be a component of eating disorders that needs further exploration, she said.