Women who averaged 150 minutes of moderate exercise (golf, tennis, aerobics classes, swimming or line-dancing) or 200 minutes of walking every week had more energy, socialized more, felt better emotionally and weren't as limited by their depression when researchers followed up after three years.
They also had less pain and did better physically, although the psychological benefit was greater.
With depression so prevalent, "there is an urgent need" to identify treatments, including non-medical options that people can do themselves, said Kristiann Heesch, who led the study.
Heesch, senior lecturer at Queensland University of Technology, and her colleagues point out in the American Journal of Preventive Medicine (January 13, 2015) that depression is expected to be the second-leading cause of global disease by 2030 and the leading cause in high-income countries.
One in 10 U.S. adults suffers from depression, according to the Centers for Disease Control and Prevention. Women are 70 percent more likely to be depressed at some point in their lives than men, according to the National Institute of Mental Health.
In addition, previous research at Queensland University, Heesch found that exercise and walking could boost physical and emotional health in women who are not depressed.
In fact, Heesch said in an email, physical activity may have an even greater effect on psychological health-related quality of life in women in their 50s and 60s who are depressed.
Her team analyzed data on 1,904 women born in 1946-1951 who answered questions about their exercise habits, physical health and mental health in 2001, 2004, 2007 and 2010. In 2001, all of them had reported at least 10 depressive symptoms, indicating mild to moderate depression.
But over time, their physical health, mental health, pain, physical functioning, vitality and social functioning all improved when they did 150 minutes of moderate-intensity physical activity or 200 minutes of walking in an average week.
More exercise was linked to greater improvements, but even low amounts of exercise had benefits.
"The good news is that while the most benefits require 150 minutes per week of moderate-intensity physical activity or 200 minutes of walking, even smaller amounts . . . can improve well-being," Heesch said.
Dr. Madhukar Trivedi, who holds the Betty Jo Hay Distinguished Chair in Mental Health at University of Texas Southwestern Medical Center in Dallas, said the study had some major strengths, including its large number of women, their physical and psychological improvements over time and the estimate of how much exercise was needed to improve quality of life.
Trivedi, who was not involved in the study, also noted that it focused on women at "the very age where risks (for depression) are high."
"It does improve quality of life. That is not a new finding but there remains skepticism in the culture that walking really does anything for depression or vitality - and this shows that it does," said Trivedi.
He noted that the benefits in the study were much stronger in the immediate future than in the long run, and that being consistently and vigorously active proved most beneficial.
These days, "more and more of these larger prospective studies are beginning to show that people with depression benefit from this," he said.
But, Trivedi noted, more research should be done on how much exercise is needed to lift depression. He said research could become more objective by using new technology, such as iPhones, to monitor physical activity instead of relying on self-reports.
"My speculation is that those women who did not see the benefit probably stopped or reduced their activity . . . it may be those are the women who need a more vigorous exercise to benefit," Trivedi said.