Why Do Intervals?

A number of you may say, “Harry, I’m not a professional or even an amateur athlete. I’m just an average person who’d like to become more fit by exercising more and eating healthy. Why should I do intervals? That’s for athletes.”

That’s a very understandable point of view. Not too many years ago I had a similar view about intervals and even about strength training. I didn’t see a purpose for intervals and thought strength training would just make me muscle-bound. The good news is that I learned the fallacies in my thinking and made some changes.

Intervals involve doing an activity at a high intensity for a period of time followed by a period of low intensity, then doing it again. The more fit you become, the more you can do. In addition to burning more calories during and after exercise as a result of interval training, you also increase your aerobic capacity, known as VO2 max — the amount of oxygen you can deliver to your muscles. Individuals with a high VO2 max live longer, among other benefits. Let’s review an example.


Let’s suppose that you use walking as one of your aerobic exercises and that your schedule is to walk two miles daily at a pace of three miles per hour. This means you’re spending about forty minutes per day.

As you improve your fitness level your body will use less energy to cover the same distance. That’s the good news; the bad news is that you’re not working as hard as you did. In order to obtain the same benefit you need to either walk longer or faster, or both.

If you increased your pace from three to four miles an hour, that should do it for awhile. But, that’s a thirty-three percent increase, a big jump. You can “sneak up” on that goal by doing intervals.

Let’s say that after you’ve warmed up you increase your pace to somewhere between four and five miles per hour for one minute. At the end of the minute you slow back down to your normal pace for two minutes and then accelerate for another minute. Over the course of the two-mile walk you do this five times.

You’ll find yourself a bit short of breath during the intervals, which is a good thing. Your heart is pumping faster; you’re working harder and burning more fat calories. This process will raise your RMR — resting metabolic rate. This means you’ll burn more calories even after you’ve completed your walk. The higher RMR can last for quite some time, depending on how hard you’ve worked.

And guess what — by doing this “up and down” walking versus your standard pace all of the time, you’ll start walking faster. You may increase your pace from three to four miles per hour in a few weeks of interval training.

Remember that with any exercise, the more we do the stronger we get and the more we need to do to obtain the same benefits. We can accomplish more in the same period of time by doing intervals.

This approach applies to any aerobic activity — running, cycling, rowing, swimming, whatever.

Let’s review the benefits: burn more calories, both during and after exercise, increase your oxygen capacity and live a longer, healthier life. Sounds like good reasons to me.