Which and How much exercise is optimal for you?
Knowing the above and practising it could give you many more years of enjoyable life. A recent Harvard University study reveals that those who do the optimal amount of exercises are 39 percent less likely to die prematurely than people who never exercised. So what is the right dose?
10 second Summary – brisk walking for half to one hour per day (150 min to 450 min per week) – supported by authoritative research and studies.
There have been many studies trying to correlate the type and amount of daily exercises with longevity. But the results are often questionable and less accurate as they are based on passive reports from those being studied; i.e based on their memory of what and how long they did the exercises. But this latest Harvard study is more authoritative. It studied and reported on aerobic exercise and all-cause mortality was conducted from 2011 to 2015. This groundbreaking research is among the first to use a fitness tracking device called a “triaxial accelerometer” to investigate clinical outcomes related to frequency and intensity of physical activity.
Based on rigorous analysis of accelerometer data from 16,741 participants (average age 72), the Harvard epidemiologists concluded that Moderate to Vigorous Physical Activity (MVPA) was associated with roughly a 60 to 70 percent lower risk of death among the most active women, compared to mortality rates of the least active women during the four-year study.
As reported in the Nov 2017 article of Psychology Today, this research indicates that previous studies, which relied on self-reporting of daily physical activity, may have inaccurately under-reported the life-extending benefits of MVPA. As first author, I-Min Lee, professor of medicine and associate epidemiologist at Harvard Medical School’s Brigham and Women’s Hospital and the Harvard School of Public Health, explains:
“The fact that physical activity lowers mortality rate is nothing new – we have many studies showing this. However, previous studies have primarily relied on self-reported physical activity, and self-reports tend to be imprecise. Based on these self-report studies, we know that physical activity is associated with a 20 to 30 percent reduction in mortality rates, comparing the most with the least active. Using device-measured physical activity in the present study, we observed a 60 to 70 percent risk reduction larger than previously estimated from self-report studies.”
Both the World Health Organization’s Physical Activity Guidelines and the ODPHD Physical Activity Guidelines for Americans recommend 150 minutes per week of moderate-intensity activity or 75 minutes per week of vigorous-intensity aerobic physical activity (or a combination of the two) plus muscle-strengthening exercises at least twice a week.
Although there is a growing consensus among epidemiologists that brisk walking as a form of moderate-to-vigorous exercise is associated with increased longevity, less than 150 minutes of moderate-intensity walking per week also appears to have significant benefits.
For example, an August 2017 Tufts-led study found that inactive older adults who added just 48 minutes of moderate-intensity physical activity per week (in the form of walking-based exercises) dramatically lowered their risk of major mobility disability. Additionally, anything above 48 minutes of moderate-intensity exercise per week was a tipping point associated with improvements in overall physical functioning when compared to adults who were sedentary.
As another example, a prospective cohort study of almost 140,000 older U.S. adults, published Oct. 19, 2017, in the American Journal of Preventive Medicine, found that moderate-to-vigorous physical activity (also in the form of walking-based exercises) for less than the currently recommended guideline of 150 minutes per week was enough aerobic exercise to significantly improve public health outcomes and lower mortality risk when compared to inactivity. That said, the researchers also concluded that walking at or above physical activity recommendations of 150 minutes per week was associated with even greater decreased risk of mortality.
The most promising aspect of the latest exercise and mortality research may be that walking is statistically the most well-liked form of MVPA in the United States. Walking is commonly referred to as the “perfect exercise” by epidemiologists because it is a simple and convenient form of physical activity that is free, doesn’t require any special equipment or the hassle of changing clothes. Plus, walking can be done at any age.
Two authoritative and impressively large-scale studies (published around 2015) provide some clarity on the blog question, suggested that the ideal dose of exercise for a long life is a bit more than many of us currently believe we should get, but less than many of us might expect. The studies also found that prolonged or intense exercise is unlikely to be harmful and could add years to people’s lives. (above was reported in New York Times Blog in April 2015)
In the broader of the two studies, researchers with the National Cancer Institute, Harvard University and other institutions gathered and pooled data about people’s exercise habits from six large, ongoing health surveys, winding up with information about more than 661,000 adults, most of them middle-aged.
Using this data, the researchers stratified the adults by their weekly exercise time, from those who did not exercise at all to those who worked out for 10 times the current recommendations or more (meaning that they exercised moderately for 25 hours per week or more).
Then they compared 14 years’ worth of death records for the group.
They found that, unsurprisingly, the people who did not exercise at all were at the highest risk of early death.
But those who exercised a little, not meeting the recommendations but doing something, lowered their risk of premature death by 20 percent.
Those who met the guidelines precisely, completing 150 minutes per week of moderate exercise, enjoyed greater longevity benefits and 31 percent less risk of dying during the 14-year period compared with those who never exercised.
The sweet spot for exercise benefits, however, came among those who tripled the recommended level of exercise, working out moderately, mostly by walking, for 450 minutes per week, or a little more than an hour per day. Those people were 39 percent less likely to die prematurely than people who never exercised.
At that point, the benefits plateaued, the researchers found, but they never significantly declined. Those few individuals engaging in 10 times or more the recommended exercise dose gained about the same reduction in mortality risk as people who simply met the guidelines. They did not gain significantly more health bang for all of those additional hours spent sweating. But they also did not increase their risk of dying young.
The other new study of exercise and mortality reached a somewhat similar conclusion about intensity. While a few recent studies have intimated that frequent, strenuous exercise might contribute to early mortality, the new study found the reverse.
For this study, Australian researchers closely examined health survey data for more than 200,000 Australian adults, determining how much time each person spent exercising and how much of that exercise qualified as vigorous, such as running instead of walking, or playing competitive singles tennis versus a sociable doubles game.
Then, as with the other study, they checked death statistics. And as in the other study, they found that meeting the exercise guidelines substantially reduced the risk of early death, even if someone’s exercise was moderate, such as walking.
But if someone engaged in even occasional vigorous exercise, he or she gained a small but not unimportant additional reduction in mortality. Those who spent up to 30 percent of their weekly exercise time in vigorous activities were 9 percent less likely to die prematurely than people who exercised for the same amount of time but always moderately, while those who spent more than 30 percent of their exercise time in strenuous activities gained an extra 13 percent reduction in early mortality, compared with people who never broke much of a sweat. The researchers did not note any increase in mortality, even among those few people completing the largest amounts of intense exercise.
Of course, these studies relied on people’s shaky recall of exercise habits and were not randomized experiments, so can’t prove that any exercise dose caused changes in mortality risk, only that exercise and death risks were associated.
Still, the associations were strong and consistent and the takeaway message seems straightforward, according to the researchers.
Anyone who is physically capable of activity should try to “reach at least 150 minutes of physical activity per week and have around 20 to 30 minutes of that be vigorous activity,” says Klaus Gebel, a senior research fellow at James Cook University in Cairns, Australia, who led the second study. And a larger dose, for those who are so inclined, does not seem to be unsafe, he said.
No doubts, of course, that any amount of exercise is better than none. Like medicine, exercise is known to reduce risks for many diseases and premature death. So don’t be complacent, even some is better than none. Just get up and work out!
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