Tuesday, 16 August 2011

Exercise and Immortality

I was reading an article by Fergus Walsh on the BBC about a study linking watching TV to life expectancy. Fairly sensible looking article, was only skimming it. Came across this excellent sentence though:
In the Lancet online, they suggest that 15 minutes of physical activity per day can reduce a person's risk of death by 14% and increase life expectancy by three years compared with inactive people.
Expect new adverts from gyms - join our gym and you could become immortal!

Of course, somewhere a time-frame is missing. Presumably the 14% reduction is within a given time frame. The abstract of the article doesn't mention a time-frame. Definitely something wrong here though.


  1. It is the odds of mortality in an active individual compared to an inactive individual. They follow a group of people for a period of time and assess how active they are at the start and then compare those who were active vs. inactive to see how many died. Then controlling for other factors (age, smoking, alcohol, ethnicity, gender etc) they calculate how many people died in each group, and then can calculate the risk of death in one group versus another. They exclude those who are already diseased, and those who die accidentally etc.

  2. You're obviously right Ash but as I said the time-frame is missing. Without it the risk of death is 100% for both groups - everyone in both groups will die at some point.

    I'm sure the research was well done but the abstract and the reporting are missing a crucial piece of data it would seem. I just found it amusing because without the time-frame, the suggestion is that exercise could make you immortal.