The research was conducted two summers ago and published August 1, 2003. The experiment randomly assigned 58 sedentary women with the average age of 21 to ride stationary exercise bikes twice for 30 minutes.
One group of women bicycled in front of a mirror, while the second group exercised in the same location with a curtain covering the mirror. The researchers measured the moods of the women before and after their workouts and documented changes.
Women who watched themselves in the mirror felt worse after their workout, according to researcher Kathleen Martin Ginis, associate professor of health and exercise psychology at McMaster.
Ginis, the principle investigator of the study, said the research focused on women since past psychological studies have shown women's moods go down if they are asked to sit and look into a mirror.
According to Ginis, the age of the participants should not have influenced the data because the study concentrated on women's activity level instead of age. The women who participated exercised less then 15 minutes per week.
"Their level of exercise is what's crucial to seeing the effect," Ginis said.
The study said advanced exercisers might not have the same problems with mirrors.
However, Marquette physical therapy professor and exercise science director Paula Papanek feels age might have been influential in the study since body image is a major problem for college-age women.
"That mirror is a harsh reality and that's difficult for people to deal with who don't have a healthy self image," Papanek said.
Papenek admitted that less experienced exercisers would be more likely to find the reflection of themselves working out in a mirror disorienting.
"We live in a society of instant gratification (in which) everyone wants to take weight off in a week," Papanek said.
Ginis and Papanek argue that the study's findings imply that fitness centers should tear down their mirrors.
Ginis said ripping mirrors out of gyms could be dangerous for weightlifters who count on them to observe their form.
Rec Plex General Manager John Kratzer said mirrors do serve an important function for both men and women who are trying to observe their postures.
"If I didn't have mirrors in our free weight room, people would have a fit, " Kratzer said. "People do utilize them to see their lifting technique."
Kratzer said the mirrors in the Rec Plex are located near the dumbbells and smaller weights, away from the cardiovascular area. He said it would be impractical for every health club to take down their mirrors since many gyms use them as a decorating tool to make rooms appear larger.
Students don't seem overly worried about possible effects that mirrors may or may not have on self image.
Graduate student Athina Stanista thinks mirrors might motivate her while exercising.
"It would be less pleasant (to work out in front of a mirror) but it might motivate me more," Stanista said.
Papanek said the problem might be that people look into the mirrors for all the wrong reasons, including to check their clothes or compare themselves to people around them.
"Mirrors are not used optimally," Papanek said. "In my opinion, they should only be used by the weights."
Instead of tearing down mirrors, Ginis recommends fitness centers looking to attract new members provide alternatives so beginners are not discouraged.
She recommends that women who are just beginning to exercise try things such as outdoor walking before heading to the gym.
"If you're a woman and you're just starting to exercise, you don't need to join a gym," Ginis said. "When you're more experienced and confident, then it's OK to go into the gym."