This week the British medical journal The Lancet published a new series of studies on the health consequences of physical inactivity. The figures are staggering. They show physical inactivity is responsible for as much as 10% of the “burden of disease” (years of life lost to mortality or disability) from illnesses as diverse as colon cancer, Type 2 diabetes, and coronary heart disease.
All told, physical inactivity is now the fourth leading cause of death around the world. More than 5.3 million people die of it every year, accounting for nearly one death in ten. That’s more than die from smoking. It’s more than die from all injuries combined (traffic accidents claim a mere 1.2 million lives annually). Yet while these have been the focus of massive campaigns aimed at their eradication, inactivity has been largely ignored. Indeed, it is in some ways encouraged.
We should be clear what we are really talking about here. It isn’t some vague condition called inactivity that is killing people. It is the specific activity of sitting, which is how most of us spend most of our days. The usual prescription for inactivity is more exercise, which certainly can’t hurt. But a 15-to-30 minute daily walk, as the Lancet advises, is of little benefit if you are sitting for six to eight hours a day at work, plus another three to four hours outside it — with a half-hour commute each way in between.