Cheer up couch potatoes! Regular stretching and balance and range of motion exercises are as good as aerobic exercise in slowing the progression of mild cognitive decline, a new study has found.

"My worry in the beginning of the study was 'What if only aerobic makes a difference? Good luck getting the majority of Americans to do aerobic exercise on a regular basis!' It's not sustainable," said study author Laura Baker, a professor of gerontology and geriatric medicine at Wake Forest University School of Medicine in Winston-Salem, North Carolina, via email.

"But we found that cognitive function did not decline over 12 months for either intervention group -- the people who did aerobic exercise or the people who did stretching, balance and range of motion," Baker said.

Rudy Tanzi, a professor of neurology at Harvard Medical School in Boston, welcomed the findings that a modest amount of exercise -- 120 to 150 minutes per week for 12 months -- may slow cognitive decline in sedentary older adults with mild cognitive impairment.

Tanzi, who was not involved in the study, has examined the role of exercise in mice genetically bred to have Alzheimer's disease and found exercise induces the birth of new neurons in the section of the brain most affected by Alzheimer's while also boosting beneficial growth factors that improve neural activity.

"So often, the benefits of interventions observed in Alzheimer's mouse models do not translate to human patients. It is nice to see that in this new study, the benefits of exercise perhaps do translate from mice to human," said Tanzi, who directs the genetics and aging research unit at Massachusetts General Hospital in Boston.

WHAT IS MILD COGNITIVE DECLINE?

The study, presented Tuesday at the in San Diego, followed 296 participants who were completely sedentary at the beginning of the experiment. All had been diagnosed with mild cognitive impairment -- the earliest stage of the slow slide into dementia.

"Individuals who have mild cognitive impairment are not cognitively normal, but they don't have dementia," Baker said. "They're fully capable of taking care of themselves, but what they have to go through to do so is exhausting.

"'I can't remember where I'm supposed to be. Let me check my calendar. Oh, I forgot to write on this calender. Let's check another calendar. Oh, I can't find that calendar. I've lost my phone. Where is the key? I can't find the key.'

"They're able to regroup in the early stages and accomplish things," Baker said, "but the toll is immense."

Participants in the study underwent cognitive testing and then were randomized into two groups. One group did moderate-intensity aerobic training on treadmills or stationary bikes, striving for a goal of 70% to 85% of : "That's about 120 heartbeats per minute for about 30 to 40 minutes for a standard 70-year-old," Baker said.

The other group did stretching, balance and range of motion exercises designed to allow them to move their body in ways that would help them navigate in real life.

"Folks in the balance-range of motion group said they were thrilled -- they could go to soccer games with grandchildren without being concerned about tripping, or they could drive and turn their neck to see the back, which they had not been able to do before," Baker said.

IMPORTANCE OF SUPPORT

Both groups exercised twice a week with a personal trainer and then two other times weekly on their own for the first 12 months. Combined, the groups completed more than 31,000 exercise sessions during that time, Baker said.

At the end of the 12 months, cognitive function had not declined in either group. That's impressive, Baker said, because a control group of equally matched people with mild cognitive impairment -- who did not exercise -- did decline.

Studies have shown that social support is also key to improving brain health. So is it possible the results of the study were due to an increase of social support and not the exercise?

"Well, we don't know for sure," Baker said. "But there is enough science showing the benefits of exercise on brain health alone. So this is not something to sweep under the carpet.

"And our recommendation would never be for people with mild cognitive impairment to do this alone," she added. "They are going to need support. So exercise alone is not a prescription. Exercise with support is a prescription, and that is going to be our recommendation."