Exercise - How much is enough?

How much exercise should we be getting?

Ever see those ads on the Internet that say “This kind of exercise ages you”, or “Too much of that kind of exercise is bad for you?”. Or how about this one: “Too much exercise can cause aging”? I’ll be honest, these headlines drive me crazy. While there is a grain of truth in the statements, I believe they are propagated to make the couch potatoes feel better. That being said, there are plenty of people who dislike exercise who might be interested in knowing how much is enough.

Enough for what?

It all comes down to your goal(s). How much exercise is enough to improve your disposition? To prevent disease and degeneration of the body? To slow the aging process? To be fit (whatever that means to you)? To improve your 5 k time? To lift more weight than you ever have? To be an athlete?

How much is enough?

Researchers in Scotland have determined that a mere 20 minutes of exercise a week of any physical activity improved the dispositions of those doing the exercise. So if improving your disposition is your goal, your job is easy: 20 minutes a week. That’s 3 minutes a day, 2 on Sunday. That sounds a little bit ridiculous to me since it would be very difficult to function without doing that much exercise.

In the 70s and 80s, exercise guidelines aimed at athleticism. The American College of Sports Medicine and other groups recommended that people engage in prolonged, uninterrupted, vigorous activity for an hour or more, several times a week. They said that people should run, swim or bicycle, the harder and more frequently, the better.

By the 1990s, formal exercise recommendations had bowed to a softer generation. Experts suggested that less vigorous exercise might be sufficient. (Which again begs the question, sufficient for what?). The recommendation became 30 minutes or more of moderate intensity physical activity daily, or almost daily.

Since these guidelines were not based on science, in the mid-2000s, the U.S. Department of Health and Human Services undertook the task of scrutinizing decades of studies about the benefits and risks of exercise and then formulated new guidelines based on their findings. Despite inconsistent findings about how much and how strenuous exercise had to be to confer disease-fighting benefits, they did reach a consensus about how much exercise was needed for “health purposes”. I read this to mean disease prevention and hence, a longer life expectancy. They found that you should walk or otherwise work out lightly for 150 minutes (that’s 2.5 hours, or 21 minutes a day) a week in order to improve your health.

All at once, or in sessions throughout the day?

It doesn’t seem to matter how the exercise is broken up. For example, you could jog for 21 minutes a day, or in three 7-minute sessions. The science says that this amount of exercise will lower your resting heart rate, increase your endurance, and result in weight loss. In an interesting test using lab rats, it was demonstrated that swimming leisurely for 3 hours was equivalent to swimming at a vigorous pace for 45 minutes, in that both resulted in significant improvements in their bodies’ ability to regulate blood sugar, a key measure of health.

This last finding I can attest to personally. Not so much the 3 hours specifically, but the ability for endurance exercise to impact blood sugar levels. As someone who is addicted to sugar, I know that regular, prolonged, vigorous exercise has prevented the over-consumption of sugar to adversely affect my blood sugar levels. Blood test results confirm my perceptions that my blood sugar levels are not out of whack. [As a side note, although I have cut down my intake of sugar significantly over the past 5 years or so, I have not cut it out completely. Despite having blood sugar levels in the normal range, I try to limit sugar as much as possible for other health reasons.]

So there you have it: twenty minutes a day is the bare minimum, if your goal is general health and disease prevention. For many, the hard part when it comes to exercise, is getting started. Once you start, 20 minutes will pass quickly and you may find yourself becoming motivated to keep increasing. Maybe your goals will change too. As your goals change, you will find that the time you invest in exercise pays more dividends than you could have imagined. If you have found the type of exercise that suits your preference, then you can start to think about increasing frequency, time, and intensity. For fun and for life!