Sunday, September 19, 2010

Healthy legs

Why should the increased height of today’s youngsters come mainly from longer legs? To put it another way, why should improved nutrition not increase the lengths of all parts of the body?

Well there must be some minimum viable size of the major organs in the abdomen & thorax, meaning that they must have a certain minimum amount of space. probably a viale maximum size too - it would indeed be very interesting to know whether the variability between humans in the size of these internal organs is less than the variability in overall size.

So if food is short, nutrition less than optimal, or some other environmental factor imposes limits to growth, resources will naturally be concentrated on preserving the length of the torso. In times of plenty then there will be enough to spare for the luxury of long legs.

There seems to be no medical concerns about this, certainly not to the extent that there is concern about people whose extra food goes towards increasing girth to the point we call obese. There are no learned papers on the health effects of height.

But problems there are. And although most of these may need environmental rather than clinical solutions (higher ceilings & doorways, bigger chairs, higher work surfaces, more legroom on public transport, longer beds – especially in NHS hospitals where good sleep might be considered essential to patient recovery …).

But should longer legs mean that we need to recalibrate the healthy values of BMI?

Other things being equal I would expect each extra vertical inch of height to provide more relative mass in the leg than in the torso – it is all muscle & bone, less fat, water or empty space. This means that over time our healthy limits for BMI might have to be adjusted upwards.

Unless of course the doom mongers are right & famine lies just over the horizon.

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