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Why an exercise pill will never work

March 23rd, 2009

On Friday, the second part of my series on athletic supplements will run in the Globe (see the first part here). Over the next few days, I’m going to post some information on other supplements that I couldn’t fit into the newspaper pieces — and believe me, there are plenty more!

Before I do that, though, I wanted to highlight a very interesting paper on “exercise mimetics” that appears in this month’s issue of Nutrition Reviews, by John Hawley (an Australian researcher who is one of the titans of research into nutrition and athletic performance) and John Holloszy. It’s a review of the adaptations within skeletal muscles and organs caused by exercise, trying to determine whether comparable benefits could ever be produced by an “exercise pill.” Martin Gibala, a top-notch research at McMaster University, pointed the paper out to me after reading this passage from my last column:

Last summer, researchers at the Salk Institute for Biological Studies in California made a splash by announcing an exercise pill that allowed mice to gain the benefits of vigorous exercise – all without setting a paw on their exercise wheels…

Hawley and Holloszy beg to differ. Administering AICAR, the drug studied by the Salk Institute group, does indeed cause an increase in muscle mitochondria, just like endurance training. As a result, rats given AICAR increased their running endurance by 44 percent. The fundamental problem our society is battling, though, is that “energy intake in excess of energy expenditure leades to weight gain and, eventually, obesity.” Having the capacity to run 44 percent further means nothing unless you actually do the running!

That’s the simplest objection they raise. The rest of the paper covers issues  ranging from whether AICAR is actually “orally active” (i.e. can be taken as a pill) to the details of gene expression required to generate new mitochondria. But as we look into the research behind various athletic supplements over the next week or so, it’s worth bearing in mind their concluding paragraph:

Prior to reading the paper [from the Salk Institute], we
were not aware that “…identification of orally active
agents… that mimic the effects of endurance exercise” is
a “long-standing, albeit elusive, medical goal”. We thought
the goal was to find ways to motivate people to exercise
and adopt healthy lifestyle choices. However, if finding
orally active exercise mimetics is really a longstanding
medical goal, we believe it will continue to be elusive for
reasons we hope are evident from this critique.

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