Swimming and cycling are non-impact loading activities and are beneficial for the associated joints involved. But the concern is that running can cause osteoarthritis of the knee and/or hip joints. But in fact, osteoarthritis is quite rare in runners/triathletes. And on the contrary, running seems to condition the articular cartilage, and has almost a protective effect against developing hip and knee osteoarthritis compared with non-runners.
It should be noted, though, that running was not found to be protective against the onset of knee or hip osteoarthritis for runners who had a long history of high volume and intensity. Such runners (i.e. elites) were found to have equivalent risk of hip and knee osteoarthritis as sedentary individuals or non-runners. In contrast, runners who ran moderate volume/intensity actually had the lowest risk of developing hip or knee osteoarthritis.
So how can you protect your joints? Simple. Keep swimming, biking and running. Your joints would be more at risk from leading a sedentary life. So stay active and enjoy the benefits.
Brad Beer is the physio for Super League Triathlon and founder of POGO Physio