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What’s the Right Dose of Exercise?

April 22, 2015

“A day without exercise is as bad as a day of smoking!” Ever heard that? Tim Cook called it “the new cancer.” Being a couch potato is risky. So tempting, but risky. But how risky? It’s so lovely and convenient to veg out and watch TV and be lazy. To act differently, I need to know the benefit. What is the benefit? This is the research.

The data: 204,542 Australians, ages 45-75, followed for 9 years for death rate, while getting precise data on amount and type of exercise – that’s the data base. That is 1,444,927 person years of mortality data in the study. That big of a study has credibility. There were 7,435 deaths in that time range; again a big number. The second study from Harvard followed 661,137 people with 116,686 deaths from ages 21-98. Again, pretty credible.

Most health organizations and the government recommend you get about 150 minutes a week of moderate exercise. Against that backdrop, these two major studies compared the mortality of non-exercisers, those who met the guidelines, those who exceeded them a little and those who exceeded them a lot. If you exercise a little, but don’t meet the 150 minutes guideline, you reduce your risks of death about 20 percent. Those who exercise the full recommended 120 minutes a week reduced their mortality by 31 percent. Wow.

That’s a lot. But it’s not the best! Those who exceeded the recommended exercise by triple or 450 minutes a week (little over an hour a day) reduced their mortality by 39 percent. And finally, those few who exercise more, up to 10 times more, didn’t get any more benefit, and in fact declined back to the level of those meeting guidelines. So, the sweet spot is an hour a day. The Australian study adds a bit more by looking at intensity of exercise. For those who got sweaty less than 30 percent of their exercise time over those who were just walking got an additional nine percent of benefit. If they got sweaty for over 30 percent of their time, they got a 13 percent extra benefit.

If you want to get sweaty, what about jogging? A third study called the Copenhagen Study looked at the optimal benefit obtained from jogging. They found a U-shaped curve that showed maximum benefit from light and moderate jogging, meaning that one to two-and a-half hours a week of jogging was best, with as much as a 78 percent reduction in mortality for slower running, not too often (2-3 times a week). Strenuous joggers had no benefit over non-jogging. (Did you get that? NO benefit.)

And compared to being sedentary? The study in Annals shows that prolonged sitting is its own risk, all by itself. And prolonged sitting of eight hours a day essentially erases the benefit of daily exercise. So walking an hour, then sitting eight hours ends up with no benefit. That makes your elevator quote: “An hour a day keeps the doctor away, as long as you don’t sit for eight hours.”

WWW. What will work for me? It looks like the Wisconsin Hiking Club has it right. They organize four to six-mile hikes five times a week, allowing you to walk two to three times a week, get your seven hours of walking in while having the company of friends and community encouragement. I’m a member and closing in on my 1,000 mile award. Add that to my dog walking, my evening strolls and an occasional morning run, and I’m close to making the perfect formula to optimal health and longevity. Exercise is something magic. Now if I could just find a way to do some heavy lifting and stop sitting so much at work. But then I would be insufferably self-righteous. But you, my friends and readers, are welcome to join us in the Hiking Club. We’re essentially free and have visitors on almost every hike. Just be at the destination listed online 10 minutes early because we leave on time.

John E. Whitcomb, M.D. is founder and medical director of Brookfield Longevity & Healthy Living Clinic. He is a Yale University School of Medicine graduate and is board certified in holistic and integrative medicine from Scripps Center for Integrative Medicine. For more information about the hiking club, visit WisconsinGoHiking.Homestead.com.

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