Monday, 16 April 2007

Is the benefit of exercise a placebo effect?

The next time you're doing the housework, try donning a tracksuit, cranking up the Rocky sound-track and viewing the whole thing as an exercise session – doing so could have a positive effect on your health.

That's according to Alia Crum and Ellen Langer, who assessed the health of 84 female hotel cleaners, all of whom worked between 32 to 40 hours per week, cleaning approximately 15 rooms per day.

The researchers then told half the cleaners, via verbal presentations, handouts and posters, that the cleaning work they perform counts as exercise and means they effectively lead an active lifestyle, easily fulfilling government recommendations for daily exercise. The remaining cleaners acted as controls.

A month later the health of the cleaners was assessed again. Crucially, those who had been reminded how much exercise they engage in at work, showed health improvements in terms of weight, body mass index, body-fat, waist-to-hip ratio and blood pressure. The control cleaners showed no such improvements.

What caused this health boost? Those cleaners reminded that their work counted as exercise didn't change their smoking, drinking or eating habits over the month, nor did they start exercising more in their spare time. However, as intended, the intervention did lead them to perceive that they engaged in more exercise at work.

“These results support our hypothesis that increasing perceived exercise independently of actual exercise results in subsequent physiological improvements”, the researchers said.

In the same way that some medicines work not because of any particular ingredient, but because of patients' belief in their healing power, the researchers concluded their findings show some of the benefits of exercise are also related to beliefs - otherwise known as the placebo effect.
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Crum, A.J. & Langer, E.J. (2007). Mind-set matters. Exercise and the placebo effect. Psychological Science, 18, 165-171.

Post written by Christian Jarrett (@psych_writer) for the BPS Research Digest.

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5 comments:

  1. pauline watts10:50 am

    I think that once these women were told that what they did was excercise, they started using their work to make it even more of an excercise regime so increasing their 'workout'. They would have felt good about doing a regular workout and getting paid for it!

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  2. Yes, this does not sound like a pure placebo effect. Telling the benefits could have spurred them on to work harder when in their jobs. Unless the study measured & accounted for such an increase in work, then you cannot claim it's all in the mind.

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  3. Anonymous7:16 pm

    Yes chris you are exactly right. There was no placebo effect here. The researchers simply planted a seed of thought about wellness and exercise which created a health awareness and in turn caused the group to work harder. We also have no evidence that this suggestion of exercise didn't change other habits in their lives such as eating etc... contrarily I bet if they had told the group that that housekeeping as a job was not exercise that they would have lost weight just do to a new awareness of their own physical health. To get a real idea of the results they would have needed three groups: one which was told housekeeping counted as exercise, one the was told housekeeping didn't count as exercise and a third group which was told nothing.

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  4. A healthy mind in a healthy body. It shows that degrading mental health to purportedly 'save' physical health is a worthless concept. All purveyors of the 'obesity crisis' ought to take note, but they won't because of course the purpose of the crisis isn't health.

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  5. I completely agree with mumboj. A healthy mind is a healthy body. That's why you don't find mental physicians anywhere:D. The key to health is a healthy thinking process
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    Sneezy Melon
    (http://sneezymelon.blogspot.com)

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