The historian George Macaulay Trevelyan wrote in 1913 that he had two doctors: "My left leg and my right".
Now a report appears to show that the simple medicine of putting one foot in front of another is a potential defence against dementia and Alzheimer's. Walking may protect the brain against shrinking and preserve memory in the elderly, according to research by US neurologists who monitored 300 volunteers over 13 years.
The data lends statistical authority to anecdotal findings, including the legendary perambulations of Alfred Wainwright, Benny Rothman and the Guardian's Harry Griffin.
Although very different in character – a grump, a communist warrior and an ex-brigadier – they lived for a combined total of 268 years thanks, in their own estimation, to lives spent largely on foot and outdoors.
The US study bears this out, with neurological tests on dementia-free people in Pittsburgh who agreed to log their walks and accept brain monitoring in 1995. Tests nine years later, followed by a further round in 2008, showed that those who walked the most cut their risk of developing memory problems by half. The study suggest that nine miles a week – or in the urban US terms of the data, 72 Pittsburgh city blocks – is the optimum distance for "neurological exercise".