Good news! This analysis of many tens of thousands of runners versus walkers found that “running significantly reduced arthritis and hip replacement risk,” but due in large part to the fact that runners were typically skinnier. Weight was a trump factor. Nevertheless, this data flies in the face of the common assumption that running is much harder on the joints. Instead, what it clearly shows is that running is either neutral or helpful, and weight is a much more important factor regardless of whether you walk or run.