It is widely accepted that exercise helps build strong, healthy bodies for life. As triathletes we pretty much have all the bases covered in terms of developing strong musculature, but what about bones? Building strong bones is a vital part of our health, yet as athletes we tend to think mainly of muscles when we exercise; after all, they are the things that tend to hurt! Just as a muscle gets stronger and bigger the more you use it, a bone becomes stronger and denser when you regularly place demands upon it. Yet in order to gain good bone density you have to consider what type of activity you do, as not all our training lends itself to bone-building.
Without strong bones we will literally start to crumble later in life, and unfortunately, not all types of exercise help. To safeguard bone health, we need the body to get used to shock-absorption. The higher the impact forces of our chosen activity, the higher the bone muscle density produced. For example, gymnasts whose sport requires massive loadings and impacts tend to have higher bone density than endurance runners. It is the high-impact activities which increase our bone density, subsequently reducing the risk of osteoporosis (brittle bones) and osteopenia (weak bones).
By contrast, participation in sports with plenty of muscular motion, but without significant loading, such as the swimming and cycling we know so well, does not bring about any significant changes in bone density, and this is what we need to be aware of. Countless hours of swimming and cycling will keep you fit and healthy in some aspects, but will do nothing to build bone strength, which is fundamental to our prolonged performance and general health. It has been found that pro cyclists often have similar (or even lower) bone density to that of a sedentary person of the same age. Pretty worrying, considering the demands they put on their bodies.
Why do cycling and swimming have little effect on bone density?
Of course, the muscular load during cycling can be very high, especially during sprinting. However, the smooth spinning nature of the pedaling action and the fact that when we cycle we are supported by our saddle, means there’s virtually no bone loading in terms of gravitational impact (unlike the shock of foot-strike during running). In distance road cycling, therefore, where sprinting is only a tiny component, the degree of total bone loading will be very low. The same goes for swimming, where there is no forceful impact and our weight is supported to a large extent.
Not all cycling is the same. Switch over to mountain biking, with the impact loading much greater (all the jiggling about and shock absorption of bike and body) and it has been found that without question, the bone density of mountain bikers is far superior to their road-dwelling counterparts. Plus it’s a great way to inject some fun and variety into your cycling regime.
As triathletes, a bit of running goes a long way to helping us stay strong for life. Weight training is great for bone density as well due to the heavy resistances. Just be aware not all types of exercise tick all boxes. Swimming and cycling will deliver big gains in terms of muscular strength and cardiovascular fitness, but you need the combined program to ensure optimum health and longevity.