CHICAGO, Dec. 15 (Xinhua) -- A Northwestern University (NU) study found that while exercise generally improved women's mood and body satisfaction, women felt even better if the instructor made motivational comments that focused on strength and health instead of on losing weight or changing the appearance of one's body.

After taking a 16-minute conditioning class, women reported more positive emotions and felt more satisfied with the shape of their body if the instructor said things like, "This exercise is crucial to developing strength in the legs; these are the muscles that truly help you run, jump, sprint like a super hero!"

Those randomly assigned to the class in which the instructor made appearance-focused comments like, "this exercise blasts fat in the legs, no more thunder thighs for us! Get rid of that cellulite!" didn't show those same improvements.

"We also asked the women to list three words that described how they felt at the end of class," said Renee Engeln, lead author of the study and professor of instruction in psychology in the Weinberg College of Arts and Sciences at NU.

"Those who heard appearance-focused comments were much more likely to write things like 'ashamed' and 'disgusted with myself.' Those in the health-focused classes were more likely to write things like 'accomplished' and 'strong.'"

The study is one more reminder that words really matter, said Engeln. "The women in this study all did the same exercises, in the same room, with the same music playing. Yet just modifying the script the fitness instructor used had a meaningful impact on the way they felt about themselves afterward.

"If we want people to stick with exercise, we need to remove shame from the equation. This study points to an easy and cost-free step that fitness instructors can take to make their classrooms healthier, more inclusive and more inspiring," Engeln added.

The study has been published online in the Journal of Clinical Sport Psychology.