Thursday, October 05, 2006

The fallacy of "fat-burning" zones and low-intensity exercise

Press Release 1: Walking not enough for significant exercise benefits.
Press Release 2: "No time to exercise" is no excuse, study shows.

By most publications, walking is the most popular form of physical activity. And why not? It's easy to incorporate walking into your daily routine. You can make a concerted effort to take the stairs rather than the elevator, walk down the hall to speak with a colleague rather than emailing or phoning them, or even take a quick 10 minute walk on your lunch hour.

For the longest time, many health-related organizations trumpeted the healthy effects of walking on cardiovascular disease, chronic disease, mental disorders and weight control. In fact, Shape Up America has dedicated a large part of their mission to their 10,000 steps a day program. The main message of this program (and others like it) is to accumulate 10,000 steps (about 5 miles) each day and your health will improve.

But are we missing something?

"Generally, low-intensity activity such as walking alone is not likely to give anybody marked health benefits compared to programs that occassionally elevate the intensity," says Dr. Vicki Harber, lead author of the study in the first press release.

Their study compared traditional exercise (using treadmills and stationary cycles) at a moderate-intensity with the 10,000 steps a day program, where subjects accumulated 10,000 steps per day.

The most significant finding was that fitness levels in the traditional exercise group improved at a rate 2.5 times that of the 10,000 steps per day group.

A separate study confirms these findings.

One group followed an interval training protocol while the other performed continuous, moderate-intensity stationary cycling. Over the study period, the interval training group trained for a total of 2.5 hours while the cycling group trained for 10.5 hours.

The results?

No significant differences in health or fitness markers between the groups.

"The most striking finding from our study was the remarkably similar adaptations induced by two such diverse training strategies," says Martin Gibala, associate professor of kinesiology at McMaster University.

My thoughts
People in the service side (personal trainers, coaches, instructors, etc...) of the fitness industry have known for a long time that harder exercise provides better results. Those doing research on physical activity and health (I used to be one of them) realize this too. However, those doing research also understand that a continuum between the benefits of exercise and the intensity of exercise exists.

So much of the American population is completely inactive that getting up and following the 10,000 steps per day program will provide health benefits, which explains the major campaigns. But it's important to realize too, that once you leave the "couch potato" behind, increasing the intensity of exercise will do more (and in a shorter period of time) than simply walking. So the continuum is getting people off the couch to doing something and then getting them to do more.

All of this leads us to walking and "burning calories." Earlier I mentioned a few of the reasons why walking is the most popular form of exericse. I intentionally did not mention fat loss (although I mentioned weight control, which is a completely different issue). You can readily verify the tie-in between walking and fat-burning zones by reading magazine headings, talking with any un-informed trainer or reading the "charts" in the fitness center or on the treadmill.

What do the headlines, trainers or chart say (or show)?

That fat-burning zones are of lower intensity than "cardio-training" zones. This may be true for "in-the-moment" metabolism, but completely off the mark in every other regard. Higher intensity exercise burns more calories, can be done in a shorter period of time and provides better health benefits than "fat-burning" zone exercise.

There is a ton of research to suppor this claim but the health conditions that receive the most benefit from higher intensity exercise are cardiovascular diseases. These include hypertension, type II diabetes, high cholesterol, metabolic syndrome and obesity.

Your take home message
Don't give up on walking!

Instead, replace some of your walking with higher-intensity exercise. Make your body huff-and-puff a little. You'll be better off in the long run.

Isn't it better to get the same (or better) results in a shorter period of time?

Of course it is. That's why working out harder is better than the alternative.

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