College-age men were twice as likely as their female counterparts to exercise to excess, and were more prone to becoming irritable and tense if they missed a scheduled workout time, according to a study published in the June issue of the journal Psychology of Addictive Behaviors.
"We think of exercise as a positive behavior, and for the most part it is, but it can also become negative when people become dependent," said Heather Hausenblas, an assistant professor of exercise and sport sciences at UF's College of Health and Human Performance. "Knowing the characteristics of excessive exercisers can help in determining who may be at risk for excessive exercise."
The research among 408 university students also found that men who worked out for the benefit of feeling better physically and mentally - rather than to look better or improve their performance - were more likely to become dependent on the need to exercise excessively, said Hausenblas, who conducted the study with Danielle Symons Downs, a former UF graduate student who now is an assistant professor at Pennsylvania State University.
Women who wanted to change their body size or shape were more likely to show symptoms of exercise dependence, a need for exercise that results in excessive and uncontrollable physical activity, the study found.
People who are exercise dependent report withdrawal symptoms such as anxiety and depressions when they are unable to work out and often give up social relationships to exercise. Their professional or school work begins to suffer, and they continue to exercise despite injuries, Hausenblas said. About 3 percent of the study participants - 2 percent of men and 1 percent of women -showed an elevated risk of developing this unhealthy reliance on exercise evidenced by their high scores on a standard scale measuring dependency tendencies.
With only about 10 percent of Americans regularly active, Hausenblas stresses the number of people who become addicted to exercise is relatively small.
"Exercise is beneficial, and it becomes a negative thing in very few people," she said. "However, even a good thing taken to an extreme can be bad."
The study also looked at the reasons people exercise - termed exercise imagery - to determine if there were differences between men and women.
Exercise imagery is divided into three categories: appearance, energy and technique. Those who exercise to change their physical form exhibit appearance imagery, while energy imagery exercisers work out for the benefit of feeling better physically and psychologically. Technique imagery is when exercisers work to improve their method by rehearsing the same movements repeatedly.
Among men, exercise dependence was related to energy imagery while among women this tendency was related to appearance imagery, the study found.
The participants, who ranged in age from 18 to 25 and were all physically active and enrolled in sport and fitness classes, were given three separate questionnaires asking them to assess their exercising habits.
While Hausenblas's research looked only at physically active university-age students, the findings likely would be similar for active adults of other ages, she said.
Her suggestion to all exercisers: Remember that too much of a good thing - working out, in this case - can have harmful effects on well being.
Craig Hall, a professor of health sciences and kinesiology at the University of Western Ontario who has conducted similar research, said Hausenblas' findings undoubtedly will lead to further studies.
"In our own exercise research we have consistently found differences between men and women, with women usually being more concerned about appearance than men," Hall said. "However, exercise dependency might not to be related to appearance, as one might initially expect, but to some other aspect of exercise. That is, whatever variable(s) are related to exercise dependency might be more prevalent in men than women."