How long will you live? This interesting study provides me with some real data supporting my view, to some degree, that the fitter you are, the longer you live. While most of western society looks for medicine to improve life expectancy, all we really need is to increase our strength. Obviously, there are exceptions to the rule, but intriguing nonetheless.
Getting a grip
The strength of your handshake predicts the length of your life
May 14th 2015
NEXT time you shake hands with your doctor, beware—you may be giving away your life expectancy. A paper just published in the Lancet, by Darryl Leong of McMaster University in Canada, reports that a simple way to assess how likely someone is to die in the next few years is to test the strength of his grip.
Using a hand-held device called a dynamometer, Dr Leong and a team of collaborators across the world tested the grips of 140,000 people aged between 35 and 70 in 17 countries. Three of these countries—Canada, Sweden and the United Arab Emirates—were rich. Four—Bangladesh, India, Pakistan and Zimbabwe—were poor. Ten, including Colombia, Poland and South Africa, were defined as middle-income. The researchers then followed their volunteers for an average of four years, and noted how many died, and what from.
There was a good deal of national variation. Swedes, it seems, have the world’s firmest handshakes, and Pakistanis the limpest. But, overall, the strength of someone’s grip was indeed a good predictor of how likely he was to die during the course of the study.
The average grip strength the team recorded was 300 newtons (the force needed to hold a 30.6 kilogram weight against Earth’s gravity). Every 50-newton drop below this was associated with a 16% rise in the risk of death, and a 17% increase in the risk of dying in particular from heart disease. It was also associated with a 7% greater risk of having (but not necessarily dying from) a heart attack, and a 9% rise in the chance of having a stroke. Among those with cancer or chronic heart disease, the strong-gripped were more likely to survive the follow-up period than the limp. The correlation held when the researchers corrected for other factors known to play a part in death rates, including age, education, drinking and smoking.
Admittedly, grip strength is not a completely reliable indicator of robustness. Dr Leong found no correlation with hospital admissions for pneumonia, for instance, or the rate of diabetes. Nor, oddly, did there appear to be a correlation with deaths from falls, a cause of injury in which muscular weakness might be assumed to play a direct role.
Interpreting exactly what is going on is hard. Because the study was observational rather than experimental, it is impossible to know whether muscular weakness is causing illness or is a symptom of illness that is already there. That matters. If the former is true, then building up strength through exercise might avert early death. If it is the latter, a person’s cards are probably marked irreversibly. Most likely, it is a bit of both, with muscle strength being a good marker of “real” ageing—in other words, of generalised biochemical decrepitude—which correlates only imperfectly with someone’s calendar age.
An advantage of Dr Leong’s method is that it is easy to execute. Dynamometers are cheap, and can be used with minimal training. Grip strength is thus simpler to assess than other signs of frailty, such as high blood pressure, body-fat percentage or blood-sugar levels. Along with a person’s waist-to-height ratio, which another recently published study confirmed is a better measure of disease-inducing abdominal fat than the familiar body-mass index, a flaccid handshake may be a warning that all is not well.
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