"To reap the beneficial effects of exercise on mood, you have to continue to exercise," says the study's lead author, Donna Kritz-Silverstein, Ph.D., UCSD School of Medicine associate professor of family and preventive medicine. "Exercising now will not protect against a future depressed mood if you stop the exercise."

Published in the March 15 issue of the American Journal of Epidemiology, the study reaffirms previous research about the beneficial effects of exercise on mood during the time frame that the exercise takes place.

However, individuals in the study who exercised in the 1980s but who were not exercising in the 1990s had lost the mood-enhancing benefits of exercise.

The researchers based their findings on 944 residents of the northern San Diego County community of Rancho Bernardo who were studied during two time periods, 1984-87 and 1992-95.

In the '80s, the residents -- non-depressed and physically able men and women between the ages of 50 and 89 -- exercised at least three times a week. Their mood, which was measured by the Beck Depression Inventory (BDI), indicated that these individuals generally had a healthy, non-depressed mood.

The same individuals were followed in the '90s, with those still exercising studied separately from those no longer exercising.

Those still exercising continued to have low BDI scores, indicating more positive mood and general well-being. On the other hand, the BDI scores of those no longer exercising had risen to levels similar to residents who had never exercised during the two-decade study.

"We determined that the increased age of the individuals was not a factor," Kritz-Silverstein says. "We also looked at a group of elderly residents who had not exercised in the '80s, but who began exercise in the '90s. They had a less depressed mood in the '90s and scores similar to those who were exercising continuously at both points in time."

Kritz-Silverstein adds that the study results were somewhat unexpected. "We thought there could be a chance that people who exercised in the past would retain a level of enhanced mood, or lower depression, even though they no longer exercised."

In addition to Kritz-Silverstein, the study authors were Elizabeth Barrett-Connor, M.D., and Catherine Corbeau, M.D.

The research was funded by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and the National Institute of Aging (NIA).

[Contact: Sue Pondrom]

16-Mar-2001