Bone health in athletes: can we learn from blood tests?

If you want to live and long and healthy life, engaging in regular endurance exercise is just about the best tool in the box. . Numerous studies have demonstrated that compared to their sedentary peers, endurance athletes who undertake rigorous training can expect to enjoy a number of health benefits. These include:

1. Enhanced insulin sensitivity⁽¹⁾;
2. Reduced blood pressure^(2,3);
3. Improved blood cholesterol profile^(2,3);
4. Reduced body fat⁽⁴⁾;
5. Reduced risk of coronary heart disease (as the result of 1-4)^(5,6);
6. Better quality of life in older age⁽⁷⁾;

The bone density conundrum

Despite all these numerous health benefits however, there’s one aspect of health that is not necessarily improved by endurance exercise, and could actually be worsened by it – and that is bone health. Bone health is defined by having high levels of bone mineral density (BMD); developing high levels of BMD during early and midlife is important because low levels of BMD are associated with an increased risk of osteoporosis. Translated literally, osteoporosis means ‘porous bones’.

If insufficient bone mass has been developed during early adulthood and then excessive bone mass loss occurs later in life, the mineral structure of the bone becomes progressively more porous. Microscopic gaps appear in the structure that both weaken the bones and make them more brittle and less able to withstand knocks and shocks without damage. In short, bones that were once strong can fracture much more easily. Once we reach the age of 40, some degree of bone mass loss due to the aging process is inevitable (see figure 1). However, osteoporosis is a more extreme condition, which is linked to a number of lifestyle factors including exercise habits and diet. Importantly, scientists now believe that large volumes of endurance training can increase the risk of osteoporosis.

Figure 1: Bone mass changes with age*