A new study in the British Medical Journal looked at the bone density of elite cyclist and runners, and found that the cyclists had thinner bones than the runners, even though many of the cyclists also lifted weights. The sports we do make our skeletons adapt in different ways over time.
Exercise is necessary for bone health—studies have long shown that children who are consistently active develop thicker, stronger bones than those who are sedentary. Many scientists agree that activities that involve sprinting or jumping will make the body increase the number of bone cells to prepare the bones to tolerate those forces. Even middle-aged or older people can maintain strong bones if they maintain activities that put more force through the skeleton.
Researchers are still not sure what activities build the bones enough—some studies show that running generates enough force to remodel bone, and other research says that it does not. It’s the same with weight training. Several studies have raised concern that non-weight bearing exercise like cycling and swimming may actually be helping the bone to get thinner because they put so little pressure through them.
A Norwegian study looked at the bone density of 21 elite runners and 19 road cyclists in their 20’s. Despite the fact that the cyclists trained much more than the runners and many more of them did weight training, they had noticeably different bones. All of the cyclists had thinner bones than the runners, and more than half of them met the criteria for low bone mineral density.
This research can’t tell us why the cyclists’ bones might be thinner—both eating too little and sweating too much have been shown to cause bone loss. This research points to serious cyclists needing to combine other activities that are weight-bearing through the bones.
Physiotherapists are experts on optimal cross-training for athletes to prevent overtraining certain muscles or building imbalances from those sports or activities that use the same muscles over and over. If you’re a serious athlete, check in with your Physio to find individualized activities and exercise to complement your own sport