Borrowed Time

Over three days in the lab they subjected the recruits to a battery of fitness tests, measuring everything from heart, lung, cognitive and immune function to muscle mass, bone density and blood flow to the brain. While muscle and bone showed little sign of ageing, heart and lung function did decline somewhat with age. But the effect of this tough regular exercise on the adaptive immune system was remarkable.

ody. One of the biggest sources of these little messengers is skeletal muscle tissue, simply because there is so much of it in our bodies, and here there's a balance to be struck, says Lord. Inactive muscle pumps out pro-inflammatory cytokines, while moving muscle makes anti-inflammatory cytokines to maintain equilibrium. ‘That's why exercise is so good for you – and why it's bad to sit for any length of time. There are now independent studies that show that how much time you spend sedentary is an independent risk factor for ill health. So you can go out, as I do, for my morning run. But if I then sit for 10 hours, I might as well not have bothered. It wipes the benefits of my morning exercise out.’

Many cells in our bodies can produce cytokines, tiny signalling molecules that carry messages back and forth as part of the ongoing chatter between them. Inflammatory cytokines communicate between the immune system and the rest of the b