Exercise: Six Minutes A Day
Chester J. Zelasko, Ph.D. | June 14, 2005

The past few weeks have brought forth interesting, yet confusing, research about exercise. How much do you really need? How intense does it have to be? How much helps you control your weight? The purpose of this Newsletter is to clarify this research so you can achieve your goals for better health, weight loss, and fitness.

One research report really grabbed headlines: “Six minutes of Exercise Just as Good as an Hour.” In a study from McMaster University in Ontario, Canada, researchers used 16 college students as subjects to see if very intense exercise could increase fitness, endurance, and muscle enzymes associated with improved energy metabolism (1). The researchers first tested the fitness levels (VO2 Peak) of the subjects on an exercise ergometer (stationary bike) by gradually increasing the resistance of the bike until the subjects were exhausted. On a different day, the subjects performed a ride to exhaustion at about 80% of their fitness level.

Over two weeks, the control group was allowed to continue normal activities, while the other group performed six sessions of high-intensity exercise built around a 30-second sprint interval termed the Wingate Test. What was novel about this exercise approach was that they performed only four 30-second sprints during the first workout session, worked their way up to seven sprints by the fifth session, then returned to four sprints the last session. The total exercise time was reported as 16 minutes over two weeks.

Researchers then had all subjects repeat the VO2 Peak test and the 80% ride to exhaustion. What grabbed the attention of researchers and what was reported in the press was that the subjects doubled their 80% ride to exhaustion--from 26 minutes to 51 minutes; there was no change in the control group. The exercise group also had an increase in a key muscle enzyme, citrate synthase.

Provocative headlines? Absolutely.

Meaningful research? Yes!

Relevant to most people exercising to control their weight and stay healthy? Probably not--even though a commentary in the same journal implied that there were health implications from the results of the study (2). Let’s examine the research a little more closely.

1. There was no change in VO2 Peak after the training.
While VO2 utilization does change slowly, especially in people who are fit (as were these students), it means that this training did not change their fitness levels. It can be confusing because they doubled their intense exercise capacity. The key is in defining terms:

VO2 Peak (also called VO2 Max) is the maximal amount of oxygen your body can process under maximal exercise conditions and is the true measure of aerobic fitness.

Sustaining effort over time is aerobic endurance or stamina. While VO2 Peak and aerobic endurance are related, they’re really two different things.

2. The most important fact is that most people in the U.S. and Canada can’t train this intensely.
While 30 seconds of exercise sounds appealing, sprint interval training as done in this study is the most intense exercise you can imagine. If done correctly, not only are you exhausted in 30 seconds, you’re ready to vomit due to the increase in lactic acid that’s built up--and you still have three to six intervals to go. It could also be dangerous for someone with pre-existing cardiovascular disease. The researchers acknowledged that in interviews and asked people to proceed with caution. The problem is that most of us feel we’re indestructible. Everyone remembers reading about the six minutes; who remembers the cautions that go with it?

3. It wasn’t just a few minutes of exercise.
Why did this training increase their stamina? After all, they exercised for no longer than 3.5 minutes on the day they did seven intervals. But that isn’t really all the exercise the subjects got: they warmed up before the intervals; they had four minutes of easy cycling between intervals; and they cooled down with slower cycling. In effect, it really wasn’t just two minutes of exercise per session--it was closer to 28 minutes on the day with four intervals and nearly 40 minutes on the day they did seven. Although they just moved their legs at a very slow rate with virtually no resistance in some phases, they were still moving their legs on the bike. To me, that helps explain why their aerobic endurance increased.

Here’s the bottom line: Interval training can increase your aerobic endurance.
The key to interval training is a controlled higher intensity effort, not an all-out 30 seconds to exhaustion. Athletes have been using interval training for years to increase their aerobic endurance, and you should use intervals as part of your training to do just that. That’s why we included intervals in our Walking for Health, Fitness, and Weight Loss booklet and the accompanying CD, Walking: The Interval Workout. (But don’t panic: we help you build up gradually--you may feel exhausted, but you probably won’t be ready to vomit.)

The problem occurs when the inference is made in the press that three minutes of exercise replaces an hour of exercise, and that it will help control body weight.

It won’t.

While it may help people get more fit, it’s only by a very narrow definition of fitness, and it won’t help with weight control--the single biggest health issue facing America, Canada, and the world today. The key to weight control is what you do with the other 23 hours and 54 minutes in your day--and that will be the topic of one of next month’s Newsletters.

The better life way is to work at it 24/7--there are no shortcuts to your better life.

References:
  1. Burgomaster KA, et al. Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans. J Appl Physiol. 2005 98(6):1985-90.

  2. Coyle EF. Very intense exercise-training is extremely potent and time efficient: a reminder. J Appl Physiol. 2005. 98(6):1983-4.
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