March 16th, 2010
05:16 PM ET

Study: Working out harder for less time effective

By Matt Sloane
CNN Medical Producer

If you're always complaining that you don't have time to exercise, your excuse-making days may now be over. A new study published in the Journal of Physiology suggests that doing short-duration, high-intensity training sessions may be just as effective as longer duration, less intense exercise. Simply put, you can do your workout in just 20 minutes and still see the benefits.

Researchers from McMaster University in Ontario, Canada, had seven men exercise for just one minute on a stationary bike at the highest intesity they were capable of. This one-minute burst was followed by a minute of rest, another minute of intense exercise, and so on, until partipants reached 20 minutes total – 10 exercising, 10 resting.

Participants were subjected to muscle biopsies before and after training, and specific attention was paid to the number of mitochondria – the tiny powerhouses in each cell.

"People’s risk of type 2 diabetes is inversely related to the amount of mitochondria in cells," said professor Martin Gibala, the study's lead investigator. "After the high-intensity training, the amount of mitochondria went up to levels that we've seen in traditional endurance training, 4-5 hours per week."

Translated: muscle fitness in just 20 minutes.

Of course interval training is nothing new – elite athletes have been training with intervals for years, but Gibala says the goal here was to prove that anybody – not just the finely tuned athletes – could train with intervals.

"We've been doing interval training research for years now, but the model we've used...is not something people can use in everyday life," said Gibala. "In this study, we used a less-extreme model of interval training using a standard stationary bike. It's a safer and more realistic for the everyday person, and still time efficient."

But, exercise experts say the only downside to short bursts of high-intensity training – by itself – can be a lack of muscle endurance.

"It depends on what benefit you're looking for," said Forrest Pecha, director of athletic training services at Emory University Sports Medicine. "If you're looking to build cardiovascular endurance, interval training only works in conjunction with longer, more sustained workouts."

If, however, you're looking to simply get in shape, and time is your enemy, Pecha says, intervals may be right for you.

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soundoff (62 Responses)
  1. Paul McAuley

    I did my dissertation on this topic 20 years ago at Southern Cal. Nice to see my hypothesis confirmed by these results.

    March 19, 2010 at 15:02 | Report abuse | Reply
  2. Maxime

    Hi Sanjay,

    I was not surprised to hear about this study, though I am surprised that this is only just becoming knowledge. I have always not believed in going out of my way to exercise. I am 33 years old in two days time, but I look like 24 people say. I have always believed that exercise is analogous to running a machine overtime; in other words, it is strenuous on the body, and leads to premature aging. rather, I am an advocate for exercising the body during normal every day life activities – lug your groceries home, run to the train if you are running late, or do yoga which is relaxing etc. I only go to the gym because it is on my way to the swimming pool, and I'm curious about the machines. At the gym, I spend nothing more that 10 minutes on the treadmill, I do 2 sets of 15 sit ups for my tummy, then I head to the pool where I swim for as long as I want (usually 20 minutes though) because its very relaxing. I swim only 2-8 times a month.


    March 20, 2010 at 18:08 | Report abuse | Reply
  3. Ben

    This article is so close to the truth.

    Unfortunately, it never mentions high intensity weight training, which, as it turns out, is the most effective and safest way to become fit in 12 minutes a week.

    But don't listen to me, or anyone else that acts like they know what they're talking about.

    Do your own research, people. Here's where to start:

    "Body by Science" by Doug McGuff and John Little (by far the best book on exercise)
    "The New High Intensity Training" by Ellington Darden (don't listen to the nutrition advice in this book, however)
    http://www.arthurjonesexercise.com (the guy that popularized HIT)
    http://www.baye.com (fantastic personal trainer, one of the best)

    "The Primal Blueprint" by Mark Sisson (great overview of the healthiest most effective way of eating. It's not dieting, this book teaches you what to eat for the long term.)
    "Good Calories Bad Calories" by Gary Taubes (long, but scientifically definitive, if you need some convincing)

    March 21, 2010 at 11:19 | Report abuse | Reply
  4. Aaron

    I will second what Phil S posted about CrossFit. I am an ex 2 sport college athlete and I thought I was in the best shape of my life at 21. Now at 28 I have more energy, less body fat, more endurance than ever before.

    CrossFit is a fitness revolution that will soon be WELL KNOWN rather than semi underground. I just started an affiliate in New London Connecticut and its amazing how quickly the word is spreading.

    I encourage you all to visit the CrossFit main site and see if there is an affiliate located near you. Its well worth it to look. Stay Fit!

    March 22, 2010 at 20:02 | Report abuse | Reply
  5. Luke Moore

    Two things you need to know that will make you fitter, healthier, stronger, and faster than ever before:

    1. Crossfit.com
    2. ZoneDiet.com

    March 30, 2010 at 10:51 | Report abuse | Reply
  6. R Ripped

    Took a while for Crossfit to be added to the discussion.

    One thing that Crossfit believes in: constantly varied. Every workout is different from the last. Routine is not good.

    Strength training is emphasized.

    Diet – the way one eats – is spelled out. They are heavily into the Paleo Diet. It's not about counting calories. Eat: nuts and berries, fruits and veggetables, lean meat, fish and seafood. No salt, add fish oil. Do not eat: grains (including rice, corn, potato), milk and cheese, legumes.

    I have trained with Crossfit for a year and a half now. It's fun and intense. I am 56 and seriously have never been in this kind of shape! My weight has dropped 30 lbs without even trying. I get complements everyday and getting to Crossfit is a top priority in my life now.

    The idea of telling women that they need to workout for an hour a day is rediculous, IMHO. I have not read the study. Proper nutrition (Paleo), intensity training, and strength training is where it's at.

    Go to Crossfit.com and spend some time understanding how they approach fitness. They go against the grain, but they really do know what it's all about.

    March 31, 2010 at 09:06 | Report abuse | Reply
  7. tom p

    There is no short route to good health and a good body. One hour a day is the min. anybody should be working out. You have 23 hours left in a day what the big deal? Do it all at once take a shower and forget about it for 23 hours.

    March 31, 2010 at 15:15 | Report abuse | Reply
  8. barbara matranga

    I liked this a lot and it is encouraging to me I am 62 yrs old and try to do cardio daily.
    Barbara Matranga

    April 1, 2010 at 10:04 | Report abuse | Reply
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Get a behind-the-scenes look at the latest stories from CNN Chief Medical Correspondent, Dr. Sanjay Gupta, Senior Medical Correspondent Elizabeth Cohen and the CNN Medical Unit producers. They'll share news and views on health and medical trends - info that will help you take better care of yourself and the people you love.