Stress-Reduction Benefits Of Exercise Demonstrated In Study

April 03, 1997

CHAMPAIGN, Ill. - Among the many research-based claims made for exercise in recent years has been that it reduces anxiety and stress.

But some researchers have asked whether people could get the same effect just by sitting quietly. Isn't the effect a result of just taking time out, of finding a distraction from causes of stress, rather than a result of the exercise itself?

No, at least not according to research by Edward McAuley, a professor of kinesiology at the University of Illinois. McAuley and graduate students Shannon Mihalko and Susan Bane, in a study published in the Journal of Sport and Exercise Psychology, found that exercise had "a significant impact on anxiety" as compared with the effect on subjects asked merely to sit still.

The study involved 16 male and 18 female U. of I. undergraduates. Each person participated in three 40-minute sessions. In one session, the subject would sit quietly in a comfortable chair in a room with few distractions. In another session, they would jog at their own moderate pace for 20 minutes on a test-lab treadmill, preceded by a five-minute warmup and followed by 15 minutes of cool-down and rest.

Since lab conditions are suspected to cause added anxiety in test subjects, thereby skewing data on anxiety reduction, subjects were asked in the third session to exercise in an activity and setting of their own choosing. McAuley defined this as the "natural environment." Almost half walked or jogged, about a quarter worked out on a stationary bike, and the rest did stair stepping, aerobic dance or some other aerobic activity. They started and finished on the same exercise time schedule as in the lab session, and the intensity of the exercise was determined by the subject.

At four points during each of the three sessions -- at the beginning and at 15, 25 and 40 minutes -- participants were asked to give oral responses to a standard inventory of 10 questions designed to measure their level of anxiety. In the natural environment session, a researcher accompanied the subject on the walk or jog or workout in the gym, and asked questions at the appropriate intervals.

"The data from the study suggest that the exercise effect is not simply a distraction effect," McAuley said, "because in both exercise sessions you see a reduction in anxiety -- whereas in the control session, sitting quietly, you just see basically a pretty flat line. The anxiety level doesn't change."

McAuley noted that, "contrary to what you'd expect," the anxiety level for the average participant actually rose at the 15- and 25-minute intervals of the exercise sessions -- meaning at the mid-point and end of the actual exercise. It then dropped significantly -- and significantly below the mere sitting level -- during the 15 minutes following exercise. And since McAuley suspects that the questions asked during exercise may be measuring "heightened physical arousal" along with anxiety, he suspects the anxiety-reducing effect of exercise may be greater than what his study demonstrated.

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