Excessive sitting down, or sedentary time, has been linked to reduced mobility, age-related muscle loss and decreased heart health – Harry Bullmore looks at the evidence, then asks the experts what you can do to combat these effects S itting down has become humanity’s unofficial default position. For most of us, work means sitting at a desk, travel means sitting behind the wheel of a car and unwinding at the end of a long day means sitting on the sofa. We are rewarded for this behaviour, too.