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Is it exercise that makes you healthy? Or the acknowledgement that you have exercised?

We all know about the benefits of exercise -  physically moving our bodies causes us to lose weight and stay healthy. It also keeps our brain healthy and allows us to learn better. 

Here's the thing. Besides actually exercising, must your brain also be convinced that you were exercising? Wait what does this mean?


When we think of exercise, we tend to think of a certain image: going to the gym, going for a run or a swim, or engaging in some type of sports. But there are many activities we do which are the equivalent of exercise, just that we don't classify it as such. For example, anyone who had done chores of mopping the floor, cleaning the toilet, chasing after the kids, or changing the sheets of multiple beds would realise that it takes as much, if not more effort than jogging, swimming, golf, bowling, table tennis and the likes. 

In other words, there are some professions that are, just because of the nature of their work, exercising daily. So shouldn't they reap the benefits of exercise?


Crum and Langer from Stanford University aimed to find out (full paper here).

  • 84 female room attendants working in seven different hotels were invited to take part in a study.

  • The attendants had certain physiological health measures taken, such as body fat and blood pressure, which are affected by exercise.

  • They were then divided into 2 groups:

  • Group 1 was a control group - measurements were taken, and continued their work as per normal.

  • Group 2 was the "informed group" - housekeepers here were given a 15 minute briefing and an information sheet (below) that cleaning of hotel rooms is actually very good exercise, and more than satisfies recommendations for an active lifestyle. Examples were given of the number of calories burnt for different housekeeping activities.

cleaning ladies.png

Image from  Dr. Alia Crum | TEDxTraverseCity

That was the only difference.  Both groups were doing the same work. One group was given information that the work they were doing was actually exercise, and one group wasn't. That's it.


4 weeks later, the same physiological measurement were retaken. And the results were shocking.  

cleaning ladies 2.png

Image from  Dr. Alia Crum | TEDxTraverseCity

In the picture above, we can see that for major indicators like weight, body fat percentage, and blood pressure, there was a appreciable difference in readings, even though there was no change in behaviour! 


The black line indicates the readings of the control group (who were not told that their work was exercise) - as expected, there was no significant difference between the before and after readings.

But take a look at the blue line - the informed group. After receiving the briefing that they were, in fact, getting plenty of exercise just from work, the informed group showed improvements in all major physiological readings. Beyond physiological improvements, participants in the informed group even felt greater job satisfaction.


It's worth going through this point again. Both groups did not report any change in behaviour between the 2 measurements - there was no increase in workload, and the subjects reported no major change in exercise outside of work, food intake, or the intake of alcohol and caffeine. They simply followed their normal lifestyle habits, they did what they have always done.  

The improvements measured in the participants were not caused by behavioural changes, but mindset changes. At first glance, this seems impossible. Losing weight or body fat, for example, is a biological process -  if they were doing the exact same thing as before, how can they possibly be losing weight or body fat? 


We broadly categorise this as a placebo effect. The placebo effects sounds like some a convenient theory of heretics and charlatans, a wonky and flawed pseudoscience. Yet the evidence for placebos is overwhelming; a placebo test is standard procedure for all pharmaceuticals - 90% of all medication do no better than a placebo pill (even when you know it is a placebo).

While there are no physical changes in behaviour, the change in mindset subsequently triggers changes in the chemical output within the body, accelerating or slowing down certain processes. Or in other words, believing in certain things cause these things to actually manifest (within certain limits). 

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