There are four types of exercise: endurance, strength, balance and flexibility. By endurance, we mean what is commonly referred to as cardio or aerobic. By strength, we often refer to anaerobic or weight bearing. All four forms of exercise confer specific benefits for healthy living. But how much do we really need and what are the benefits? Is 60 minutes better than 30 minutes and 90 minutes better than 60? Is it better to do more intensive exercise for a shorter period of time or less intensive for a longer duration? Is endurance better or more important than strength? The answers depend on what your goal is. If your goal is longevity than the answer may be different than if your goal is to have more pronounced muscles.
For many years, doctors have been more comfortable prescribing medication than an exercise routine. That may be about to change. A new study from the Harvard School of Public Health now offers doctors specific exercise prescriptions. In the study led by I Min Lee, a professor of medicine at Harvard Medical School, researchers analyzed data of more than 650,000 people older than 40 who were followed for an average of ten years.
Here's what they found:
1. Subjects that completed the equivalent of 75 minutes of brisk walking each week--roughly 11 minutes per day--lived 1.8 years longer than those who did not exercise at all.
2. Subjects that completed the equivalent of 150 minutes (as federally recommended) of brisk walking each week--roughly 22 minutes every day or 30 minutes five days a week day--lived 3-4 years longer.
3. The benefits plateaued at about 43 minutes of brisk walking a day.
The noted gains applied to people at all weight levels, including the obese. This means that even if weight was not lost, the benefits of exercise were still realized.
The researchers focused on brisk walking because it is the most commonly reported exercise, but any moderate intensity exercise, from riding a bike, doing gardening and yard work, running around with the kids, would be just as good. The only requirement is that you get your heart rate beating to a level where speaking is still comfortable, but singing becomes difficult (that means hard for you to sing, not for people to hear you sing.)
The researchers also concluded that those who engage in more vigorous exercise, say running or playing basketball, enjoyed the same gains but in half the time. In other words, the benefits of vigorous exercise plateaued at 21.5 minutes per day for the more intense exercisers. In fact, a previous study showed that women who exercise 60 consecutive minutes a day actually burned fewer calories over the entirety of the day than those who only exercise for 30 minutes. Combining the two studies, we can extrapolate that too much exercise may be counterproductive. That said, moving around all day, as opposed to sitting for large parts of it, is known to confer many benefits. From my perspective, I advise patients in general to do five minutes of moderate activity for about eight or nine hours during the day. I believe, although it has not yet been proven scientifically, that this will confer the most benefit. As always, follow the advice of your physician who knows your personal medical history and limitations.
This new study is not the final say on exercise as it only addressed longevity, but it offers an excellent guideline for improving your longevity. As other recent studies have shown, exercise may also help prevent dementia and even cancer. So if you have been sitting reading this blog, may I suggest you now get up and get moving. It will probably extend your life.