Exercise Intensity

Gretchen Becker Health Guide
  • There are people whose idea of fun is to go to a gym and work out until they’re sweaty and exhausted. I’m not one of them.


    So if you’re like me, you might be interested in a new study from the Netherlands that suggests that longer, less-intense bouts of exercise, like walking, may be more beneficial for your diabetes than short, intense bouts of exercise, at least as long as the number of calories expended by the long walks are the same as those you’d expend riding a bike at full speed for a shorter time.


    The number of calories you burn with exercise depends on the distance you go, not how fast you cover that distance. So walking a mile in 30 minutes burns the same number of calories as running it in 5 minutes. The walking just takes longer. (And I think it’s much more enjoyable, as you can look at the scenery instead of focusing on speed.)

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    The intense exercise that gets your heart rate up, however, may be better for cardiac function. So this study doesn’t show that intense exercise is bad.


    In this study, 18 young, healthy adults were divided into three groups. In the first, they were told to sit for 14 hours each day and not indulge in any form of exercise. (I would have loved to have been in that group!)


    The second group sat for 13 hours a day and exercised vigorously for an hour. The third group substituted 6 hours of sitting with 4 hours of walking and 2 hours of standing.


    The sedentary group burned about 500 kcal less than those in the other two groups, who burned about the same amount.


    Cholesterol and lipid levels improved slightly when the subjects exercised vigorously for an hour a day, but improved significantly when they were active for longer periods at low intensity.


    Unfortunately, very few Americans with jobs can afford to spend 4 hours walking. The participants in that group logged almost 28,000 steps, which is a lot. I have trouble reaching 10,000 steps most days. It would be interesting to see what the effect of various durations of walking were. Do you have to walk almost 4 hours? Would 3 hours be enough? Or 2 hours? Or 1 hour?


    “Walking” doesn’t have to mean striding down a path carrying arm weights and pumping your arms. It could be getting up from your desk and going to the water cooler. Could frequent short walking breaks have the same effect as longer bouts of walking?


    We don’t know yet, but this study is good news for older people with diabetes who may also have other conditions that won’t let them do vigorous activities. And it’s also in line with the idea that it’s sitting for long periods that causes health problems, as David Mendosa described in a 2011 article.


    So if you can’t do a lot of exercise, even if you can’t leave your house, don’t despair. Just getting up and walking around should help with your diabetes control. And no, I don’t mean getting up and going to the fridge for another piece of cheesecake.


    What I find interesting is that this study is in line with a recent study of exercise among the South American Tsimane, who live in the Amazon basin and still maintain much of their traditional lifestyle, although this is changing rapidly. The Tsimane seem to be free from most of the “diseases of civilization,” like heart disease and diabetes, as well as having low rates of obesity, so researchers wondered if a rigorous lifestyle with a lot of exercise might explain their health.


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    They carefully measured the energy expenditure of the Tsimane and found to their surprise that there was no relation between physical activity and obesity or body fat. They did expend a little more energy than the average American, but not a lot more.


    In fact, the “Tsimane do not spend much time in ‘vigorous’ activity but instead spend a lot of time in light to moderate activity. Rather than characterizing the Tsimane as vigorously active, I’d more safely say they are not sedentary,” said Michael Gurven, who led the study.


    Bingo! That’s about the same finding as the Dutch study.


    Think about it. Except for athletes, our recent ancestors didn’t jog. They didn’t lift weights. They didn’t go to a gym. But when they needed food, if they didn’t produce it themselves, they usually walked to the store. The children walked to school. (I used to roller skate to school in good weather.) The women spent hours standing up cooking, cleaning, and doing laundry. The men probably varied more in the physical intensity of their jobs, ranging from stevedores working 12-hour days to clerks, but even the clerks often walked to work or walked to a bus stop and walked out for lunch.


    What they didn’t do was drive to work, sit at computers all day, drive home, and watch TV from a lounge chair. We know that people who are bed-ridden develop insulin resistance.


    We tend to have the idea that the past was some kind of Golden Age in which everyone was thin and healthy, but of course that’s not true. There have always been thin people and fat people. One of my grandmothers was fat in her later years, and, according to a photograph I have, so was her mother-in-law. This would have been in the 1920s, long before the “obesity epidemic.”


    What is different in today’s climate is that the fat people are fatter than they used to be. The thin people may also be fatter than they used to be. My grandmother had in her attic some shirts that had been worn by my great-grandmother in the 1890s. Even as a small, relatively thin teenager, I couldn’t get them on. The sleeves were too tight.


    So if you can, try to get up out of that chair and go for a walk. Or do something that you can do standing up. David Mendosa uses a standing desk.


    Even if you don’t have 4 hours of free time every daily, you can try to arrange your life so that it requires getting up and doing something periodically instead of sitting passively in a chair.


    You needn’t feel guilty if you are unable to jog or carry 50-pound weights as you go. Simply walking at a slow pace may be the best thing for your diabetes after all.


    The free full text of both articles is available at PLOS One, which you can reach through links in the Science Daily articles.



Published On: February 16, 2013