Earlier this week I stumbled across an interesting article about exercise offsetting a sedentary lifestyle.
Instead of making you follow the link, here is my own condensed version of the article.
Over the last few years, emerging research has suggested that sitting for long hours every day--like most people do at work--increases your risk for heart disease, diabetes, and early death. And this was shown to be true even if you engaged in regular physical activity.
This news was troubling to gym-goers everywhere. It also bothered Mark Peterson, Ph.D., M.S., assistant research professor of the University of Michigan School of Medicine. "I thought, 'Could this really be true? Is it possible that sedentary time is trumping my exercise time?"
So he decided to dig into the research himself.
"What I found is that even though the studies (referenced above) were extremely well-conducted, they didn't necessarily tell the whole story. In many cases, the data was gathered with questionnaires, and people were simply asked if they exercised on a certain day or not. There wasn't an accurate way to account for the intensity or duration of that exercise. And it was usually a totally subjective measure," says Peterson.
So, if a person went for a casual 10-minute walk, it counted the same as if they did 45 minutes of intense interval training. "As a result, exercise wasn't found to have any impact on the increased disease risks associated with being sedentary."
Peterson decided to see what would happen if you actually accounted for exercise intensity. He pulled data from the National Health and Nutrition Examination Survey (NHANES), an ongoing study that provides detailed physical activity data for thousands of people across multiple years.
"The NHANES data provides objective measures of activity with accelerometers," says Peterson. "So we knew how hard and how long the people were exercising. And we looked at different levels, over several years: light, moderate, and vigorous activity, as well different combinations."
The finding: people who did the highest amount of moderate and vigorous activity a day weren't at any increased risk for heart disease or diabetes, regardless of how much sedentary time they logged.
The magic number for the protective effect, based on this research, appears to be a minimum of 30 to 45 minutes a day of moderate to vigorous activity, at least five days a week. "For cardiovascular exercise, that equates to anything over 70 percent of your max heart rate," says Peterson. "The type of exercise you do doesn't necessarily matter, and it can be done all at once, or even accumulated in shorter bouts throughout the day."