"We have this perception we should be doing 10,000 steps a day," says lead author Dr Melody Ding, "but it's not evidence based". The figure of 10,000 steps can be traced back to a 1960s marketing campaign in Japan. In the run-up to the 1964 Tokyo Olympics, a brand of pedometer was launched called the manpo-kei, which translates as "10,000-step meter". Dr Ding says this figure was "taken out of context" and became an unofficial guideline, which many fitness trackers and apps continue to recommend. The Lancet study analysed previous research and data on the health and activity of more than 160,000 adults around the world. Compared with those who walked 2,000 steps a day, it found that 7,000 steps was linked to reduced risk of: cardiovascular disease - down 25%cancer - down 6%dementia - down 38% and depression - down 22% However, the researchers say some figures could be less accurate than others as they are drawn from only a small number of studies. Overall, their review suggests even modest step counts of around 4,000 steps a day are linked to better health compared to very low activity of just 2,000 steps a day. For most health conditions, the benefits tended to level off beyond 7,000 steps although there were additional advantages to walking further for the heart.