Sitting at dinner with friends last night, the subject of exercise came up. One of my fellow diners made, I think, a perfectly valid point when he commented that exercises such as running and cycling are not particularly effective where weight loss is concerned. I supported his point of view by quoting some science on the subject (see here for some evidence on this). Another person at dinner last night followed this up with a comment that went along the lines of “Whenever I’ve got on a health kick and run myself to a standstill on a treadmill several times a week it’s never made any appreciable difference to my weight.”
Another person in attendance who is, I know, very active, fit and healthy, got quite animated about this ‘anti-exercise rhetoric’ and vigorously made the point that exercise is not just about weight loss, as it promised benefits with regard to physical and mental health and even self-esteem. I told him I could not agree more. (I just think we need to be honest with regard to what aerobic exercise can do with regard to weight loss.)
This conversation popped back into my head on reading this morning on reading a study published today in the British Medical Journal regarding physical function and overall risk of death . The authors of this study reviewed all relevant studies which assessed measures of physical function such as grip strength, walking speed and balance and overall risk of death in elderly people.
It turns out that for each marker of physical function they assessed, the better it was, the less likely individuals were to die.
Now, so-called ‘epidemiological’ studies of this nature cannot be used to conclude that better physical function leads to protection from mortality, only that the two things are associated. As the authors point out, one potential explanation here is that those of better health (and at lower risk of death as a result) fare better in terms of physical function.
To prove ‘causality’ we would need so-called ‘intervention’ studies where individuals are randomised to ‘exercise’ and ‘non-exercise’ groups and then followed up for long periods of time. I cannot find a study of this nature in the scientific literature, and doubt actually that one will ever be done.
So, all we have to go on is epidemiological data, which as a whole points strongly towards activity and exercise being good for our general health and overall risk of death. Click here for a post about another relevant study which supports this idea.
1. Cooper R, et al. Objectively measured physical capability levels and mortality: systematic review and met-analysis. BMJ 2010;341:c4467