http://goo.gl/otquqa
We think age has much more to do with how people function than how many birthdays they’ve had, so measuring function is the crucial thing. Our research agenda calls for looking at different measures of functioning because aging is multidimensional. We started with hand-grip strength, a measure of upper-body strength.
Q. Why did you begin there?
A. Hand-grip strength is an amazingly good predictor of future rates of mortality and morbidity, or sickness. It’s been measured for individuals in surveys across the world. We now have comparable data on about 50,000 people from the U.S., many European countries, Japan, South Korea, China. A substantial body of research suggests that this can be used as a reliable predictor of aging.