NEW YORK (Reuters Health) - Women who exercise regularly after menopause tend to maintain their physical strength and mental acuity longer than those who don't, according to a new review of past studies that found exercise that gets the heart rate up is best.
"We found that all the studies showed that physical activity was associated with decreased rates of cognitive decline and that even becoming active in later life as opposed to a lifetime of physical activity still lowered the risk compared to those who were inactive," said Debra Anderson.
Anderson worked on the study at the Institute of Health and Biomedical Innovation of the Queensland University of Technology in Kelvin Grove, Australia.
She and her team reviewed 21 studies published between 2009 and 2014 assessing exercise or leisure time physical activity among women ages 65 and older. Ten were randomized controlled trials, the most rigorous kind of study, in which women were randomly assigned to different exercise programs or to no program.
Some studies involved structured group exercise programs aimed at hitting certain heart rates and energy expenditures while others involved balance and strength training programs or yoga classes.
Higher physical activity levels were always linked to slower physical decline and better fitness. Exercise generally seemed to preserve brain health, too, although the studies didn't agree on the strength of that association. Some concluded that a woman's brain function at age 50 largely predicted her mental faculties at ages 60 and 70, while others found that mental decline was strongly linked to being sedentary, the authors write in Maturitas.
"We found that moderate to vigorous exercise is better than mild and gentle exercise," Anderson told Reuters Health in an email. "There was a dose response in moderate to vigorous exercise which showed more was progressively better."
Current guidelines call for older adults to get the equivalent of 30 minutes of moderate exercise five times per week. But doctors might consider "prescribing" more intense exercise to older women, the authors suggest.
"Based on our findings we feel this should be 30 to 45 minutes of moderate to vigorous activity at least five times per week for midlife and older women," Anderson said.
Previously, older women have been encouraged to keep their exercise moderate, but now it seems very important that women exercise to a point where they cannot finish a sentence while exercising and breathe hard and sweat, she said.
"I would encourage someone who has not exercised at this intensity before to see a general practitioner for a referral to an accredited exercise physiologist to talk with them on how to build up to this level," she added.
The idea that breaking a sweat helps the brain is not new, said Selena Bartlett, a neuroscientist at Queensland University of Technology. She was not involved in the new study, but collaborates with Anderson on activity and cognition research.
It's not clear exactly how exercise helps the brain, Bartlett told Reuters Health.
"One thing we absolutely know is it builds muscle and strengthens the skeletal frame, and also brings oxygen and blood flow to the brain," she said.
Keeping active helps make aging easier for everyone, not just postmenopausal women, Bartlett said, but that group might derive particular benefit. Estrogen levels decrease during menopause, and the hormone has a role in preserving brain cells and forming new memories.
"Especially for postmenopausal women, the intensity matters for brain and body health," Bartlett said.