Staying active can help keep your brain in good shape, say two studies that tracked exercise and mental decline over time.
And the extra benefits of walking daily are clear in these studies.
In the first, which followed more than 2,200 Hawaiian men aged 71 to 93, those who walked the least (less than a quarter mile a day) were nearly twice as likely to be diagnosed with dementia than those who walked the most (more than two miles a day) over the next seven years. Men who walked between a quarter and one mile a day had a 70 percent increased risk.
In a second study, which tracked nearly 19,000 women aged 70 to 81 for at least nine years, those who exercised the most had a 20 percent lower risk of cognitive impairment than those who exercised the least. Women who walked for at least 11/2 hours a week scored better on memory, attention, and other tests than women who walked less than 40 minutes a week.
Exercise and weight gain
Another one of the extra benefits from walking daily is reduced weight gain.
It should be noted, though, that it may take an hour a day of exercise for women to avoid gaining weight.
Researchers tracked more than 34,000 healthy women who averaged 54 years of age when they entered the study in 1992. After 13 years, the average woman had gained almost 6 pounds. However, the 4,540 women who gained less than 5 pounds during the study reported walking briskly or doing similar moderate exercise for roughly one hour a day throughout the study.
Women who exercised for less than an hour a day were roughly 10 percent more likely to gain at least 5 pounds within about three years. Exercise was not related to weight gain or loss in women who were overweight or obese when the study began, suggesting that preventing weight gain is critical.
Exercise and diabetes
Diet and exercise can delay diabetes for at least a decade, and those lifestyle changes work better than a popular drug.
In the late 1990s, the U.S. Diabetes Prevention Program randomly assigned, to one of three groups, roughly 3,200 people who were at risk for diabetes because they were overweight or obese and had fasting blood sugar levels that were elevated (at least 5.3 mmol/L) but not high enough to warrant a diagnosis of diabetes (7.0 mmol/L or higher).
Those assigned to the intensive lifestyle group were encouraged to lose at least 7 per cent of their body weight and to exercise for at least 2 1⁄2 hours a week. The drug group was given the oral diabetes drug metformin (850 milligrams twice a day), and the placebo group was given lookalike but inactive pills.
In 2001, the researchers halted the study one year earlier than planned because the results were so clear: The risk of diabetes was 58 per cent lower in the intensive lifestyle group than in the placebo group. Metformin cut the risk by 31 per cent versus the placebo.
In a follow-up study, the researchers invited the people from all three of the original groups to attend coaching sessions on intensive lifestyle changes every three months. During the next six years, the people from the original intensive lifestyle group maintained their lower risk of diabetes, while the risk of people from the original drug and placebo groups declined.
But since the people in the original lifestyle group had a head start, their 10-year risk of diabetes was 34 per cent lower than the risk of those in the original placebo group. The metformin group’s risk was 18 per cent lower than the original placebo group’s.
Aerobic exercise and strength training
“Both strength training and aerobic exercise have benefits,” explains Brenda Davy, associate professor of nutrition at Virginia Tech in Blacksburg.
“Aerobic exercise may be more likely to produce a modest weight loss because you can expend more calories,” she notes. But older people who have arthritis or who use a walker may prefer strength training.
“Some may find a resistance training program more appealing than aerobics,” says Davy.
Clearly, doing both is best. When researchers assigned 262 people with diabetes to aerobic exercise, resistance training, both, or neither for nine months, only those who did both lowered their long-term blood sugar levels.
“In people with diabetes, the combination has a clear benefit,” says Davy. “I wouldn’t want to say one is superior.”
How much strength training is enough? Shoot for 8 to 12 repetitions of 8 to 10 exercises at moderate intensity two to three times a week.
“You can only do strength training effectively every other day because you’re actually damaging the muscle, and it takes a couple of days to repair itself,” says Sheri Colberg.
And try for at least a half-hour of brisk walking or other aerobic exercise at least five days a week.
“That helps, but there’s a limited amount of time and a limited number of calories you’re going to expend in 30 minutes or even 60 minutes,” notes Colberg, who chaired a committee that issued a joint position statement on exercise and type 2 diabetes from the American College of Sports Medicine and the American Diabetes Association.
“What helps the most is being active all day long. Get up and walk around. Get a treadmill in your office. Don’t sit at the computer all day.”
What to do
Go for a walk…every day. Shoot for an hour of exercise a day if you can. But don’t give up. Any exercise is better than none. Does an hour a day seem like too much? Think of it this way: Largely sitting or sleeping for 23 hours a day is too much. And aren’t the extra benefits of walking daily worth it?
Sources: J. Aging Res. 2011, doi:10.4061/2011/127315; Med. Sci. Sports Exer. 42: 2282, 2010; JAMA 304: 2253, 2010; Lancet 374: 1677, 2009; JAMA 303: 1173, 2010; J. Amer. Med. Assoc. 292: 1447, 1454, 2004.