Friday, March 12, 2010

Bursts: A quicker way to fitness?

New research is suggesting you can get much more health benefit in much less time by using bursts of increased intensity.

This flies in the face of lots we've learned in the past generation about exercise and health--that you need to put in the time for good overall fitness. Indeed the researchers concede that their work needs to be expanded upon.

The new paper is entitled “A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms.” Its authors are Jonathan Little, Adeel Safdar, Geoffrey Wilkin, Mark Tarnopolsky and Martin Gibala, most of whom are with McMaster University in Hamilton, Ontario, Canada. It's in the March 15, 2010, The Journal of Physiology, a publication of The Physiological Society.

For those of us who exercise regularly and are also challenged for time, this is exciting stuff. Our own exercise credentials include track running, marathons and triathlons, some bike racing and both long and short-distance canoe paddling, and a little time coaching at various sports.

The amazing benefits of bursts of intensity, whether through the various forms of interval or fartlek training, are certainly clear. They can turn a middle-of-the-pack athlete into a contender within weeks, presuming a good base of aerobic training.

The suggestion of the new research seems to be that the base of long distance is not needed—at least for good muscle tone.

The Canadian team had earlier shown that extreme-intensity bursts were beneficial. The newest work indicates important health benefits even from high-intensity intervals that are well short of extreme.

Here is one release on the report, written by the publisher's Mary Arbuthnot. She says that a new study “adds to the growing evidence for the benefits of short term high-intensity interval training (HIT) as a time-efficient but safe alternative to traditional types of moderate long term exercise.” Another release by Jane Christmas of McMaster University, is here.

Author Gibala, who is chair of the McMaster Department of Kinesiology, says that "Doing 10 one-minute sprints on a standard stationary bike with about one minute of rest in between, three times a week, works as well in improving muscle as many hours of conventional long-term biking less strenuously."

Not to be a naysayer, but that's still 20 minutes of training, three times a week, which pretty much fits in with traditional recommendations for basic fitness. But for advanced fitness?

The latest study used standard exercise bikes, and had subjects pedal at 95 percent of maximal heart rate during their bursts. (Maximal heart rate is determined during a supervised cardiac stress test, but for a general number, subtract your age from 220, to get your maximum heart rate.)

After six training days over a two-week period, the interval training subjects had comparable results to those doing longer-time, but lower-intensity workouts: “improved exercise performance and muscular adaptations that are linked to reduced risk of diseases such as Type 2 diabetes,” the McMaster release said.

The scientists argue that exercise of one type or the other may allow individuals to function with less risk of heart attack, diabetes or stroke.

In his initial work, published in 2006, Gibala conducted research using young, active individuals, and used intervals in which they exercised as hard as they could. Here's Gibala's own report:

“Sixteen young men performed six training sessions over two weeks. Eight subjects performed between four and six 30-second bursts of 'all out' cycling separated by four minutes of recovery during each training session. The other eight subjects performed 90-120 minutes of continuous moderate-intensity cycling. Total training time commitment including recovery was 2.5 hours in the sprint group, whereas the endurance group performed 10.5 hours of total exercise over two weeks. Both groups showed similar improvements in exercise performance and the muscle's ability to resist fatigue.

"Our study confirms that interval-based exercise is indeed a very time-efficient training strategy. It is a demanding type of training and requires a high level of motivation, however it might be the perfect option for those who say they have no time to exercise."

In his own press release at that time, Gibala said, “"The most striking finding from our study was the remarkable remarkably similar adaptations induced by two such diverse training strategies.”

Here is a 2007 paper in which Gibala describes his results and comments on their health impacts.

It is not clear from this research whether these techniques also provide a short-time way to train for endurance events like long canoe races, long bike races or marathons and triathlons.

And it is not clear whether these short workouts provide larger health benefits, beyond providing strong skeletal muscles. Write the authors: “Future research should examine whether practical low-volume HIT can improve markers of metabolic health in healthy individuals and those at risk of developing chronic inactivity-related disease to determine whether this type of training is an effective health-enhancing exercise strategy.”

Some companies use Gibala's work to promote programs that use exceedingly short workouts of four to six minutes. But it is clear that his workouts are running 20 minutes or longer, whether they're 4 to 6 extremely intensive half-minute bursts with four-minute breaks or 10 less intensive one-minute bursts with one-minute breaks.

© Jan TenBruggencate 2010

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