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Can 7 minutes of exercise per week make you healthier?

Thursday, January 29, 2009 Posted by Peter Janiszewski, PhD
So suggests a new study by Babraj et al. published yesterday in the online journal BioMed Central Endocrine Disorders.

Specifically, the authors found that 2 weeks of very short-duration but high intensity aerobic exercise improved glucose tolerance by 12% - an effect that persisted for a few days after the last exercise session.

Photo by: jcheng

The study had 16 young (age: 21 years) and lean (BMI: 23.7 kg/m2) males perform two weeks of high-intensity training on a cycle ergometer. Over the two weeks they performed a total of 15 minutes of actual exercise, with 3 sessions per week, each consisting of 4-6 30-second sprints on the ergometer.

Post training, both the glucose and insulin area under the curve during an oral glucose-tolerance test improved, by 12 and 37%, respectively.

What makes this finding even more interesting is the notion that these metabolic improvements were achieved after an expenditure of only 250 kcal/week.

The authors suggest that the increased glucose tolerance can at least be partly explained by an increase in the levels of the glucose transporter, GLUT-4, in skeletal muscle, as a prior study of similar training brought about a 20% increase in GLUT-4 levels.

While the title of today’s post may be provocative, there are a few caveats to the practical implications of this study.

For one, 250kcal energy expenditure per week is unlikely to lead to any significant change in body composition (loss in fat and/or increase in muscle) – the mechanisms by which many health benefits of exercise are at least partially mediated. The implication for weight-loss is even more laughable.

Additionally, for most sedentary individuals, going from couch to high-intensity short-duration training may be a recipe for disaster. I’m sure we are all aware of the significant spike in heart attacks that often occur after the 1st big snowfall of the year. Every year I see the same story on the news: sedentary man goes to shovel his driveway – this becomes the most intense activity he has done since last winter, and he ends up at the hospital. Thus, while this type of training may be well tolerated by lean 20-year olds, I doubt it will be very applicable to the majority of the general population.

Knowing how much people like quick fixes for all ailments, I almost fear advertising the results of this study. Nevertheless, while the general applicability of this study is poor, the results are certainly interesting.


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2 Response to "Can 7 minutes of exercise per week make you healthier?"

  1. Darya Pino Said,

    Good analysis. I am not sure how smart it is to go from 0 to full throttle when you are talking about your body. This data can only really make a difference to people who don't work out AT ALL, and those people are the least likely to be able to tolerate high-intensity workouts.

    Rather than trying to trick your body into being healthy, why not start with easy, fun exercises a few times a week and build over time?

    Oh wait, that takes real time and dedication. My bad ;)

    Posted on January 29, 2009 at 2:36 PM

  2. Peter Janiszewski, PhD (Cand.), MSc Said,

    Thanks for the comment Darya. You are absolutely correct - for those who are already regulalry active, this regimen will likely not provide much further benefit, and for people who are currently sedentary - might be the worst idea as an introduction to an active lifestyle. So in the end the applicability of the findings are questionable at best.

    Posted on January 29, 2009 at 5:07 PM


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We are PhD students in the School of Kinesiology and Health Studies at Queen's University in Kingston, Ontario. Our research focuses on the relationships between obesity, physical activity, and health risk. This blog is our attempt to consider the many "cures" for obesity that we read about on a daily basis. Enjoy.


The opinions expressed here belong only to Peter and Travis and do not reflect the views of any organization. Any medical discussion on this page is intended to be of a general nature only. This page is not designed to give specific medical advice. If you have a medical problem you should consult your own physician for advice specific to your own situation.

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