The researchers conducting the study were Brian Focht, a study co-author and an assistant professor of health behavior and health promotion at Ohio State University, Thomas Raedeke and Donna Scales, both researchers at East Carolina University, in Greenville, N.C.
All the women taking part in the study had social physique anxiety - a disorder in which someone chronically worries that others are critiquing his or her body.
The women participated in one of four 45-minute step-aerobics classes. The same instructor taught each class, although she emphasized health over appearance in two of the classes. In the other two classes, she emphasized appearance over health. One class in each scenario included a mirror, which research has shown can negatively affect how someone feels, particularly a woman who is concerned about her physical appearance.
The research showed that the participants not only enjoyed a step-aerobics class more when the instructor focused on the health-related aspects of the workout, telling them how exercise will make them more fit, but were also more likely to say that they would try a similar class in the future.
Women who were taught by an instructor who emphasized appearance by making comments about how the exercise would tone their legs or other body parts, did not have the same reaction.
The women in the health-oriented class reported that they felt more engaged in the workout as well as revitalized and less exhausted after class than did the women in the appearance-oriented classes.
From this, the researchers concluded that it was the instructor who made all the difference, and that fitness experts should lay more emphasis on getting fit, than getting slim.
"Women who have this disorder usually are interested in exercise to improve their appearance, but an instructor who emphasizes physique during a workout may deter such students from coming back," said Brian Focht
The study's results appear in a recent issue of the journal Psychology of Sport and Exercise.