If you want stronger bones, you should start running! Running has shown superior improvements in bone density (especially in the legs) compared to other exercises like rowing or cycling. This is exciting news, but researchers say that this only occurs as long as you consistently increase your duration and difficulty levels. This is because over time, your body will adjust to the level you are running at and the increase in bone density will come to a halt. To build bone density in other areas of your body try combining running with different weight-bearing exercises.