From a Vienna colleague:

https://blog.iiasa.ac.at/2016/02/10/what-does-your-walking-say-about-your-true-age/#.VrxhgDtoQpI.twitter

snip:
"Did you ever notice that you walk faster than your friends, or are you the one lagging behind? Your walking speed doesn’t only reveal how fast you walk; it can predict survival and the “slowing down process” and – according to a recent study – it can tell how old you are in terms of your physical fitness. If you are highly educated, or work in a non-manual job, you could be up to 15 years younger when it comes to your “walking age”—the age you are supposed to be according to your physical performance."

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Doctoral Student
Institute for Multi-Level Governance and Development 
Department of Socioeconomics 
WU/Vienna University of Economics and Business
Austria
WU: www.wu.ac.at/mlgd/en
Personal: annhartell.weebly.com