While cycling is said to be one of the best things people can do to stay healthy, a new study has shown a striking correlation between bicycling and the onset of osteoporosis.

A low-impact sport that puts little mechanical load on the bones and joints, bicycling is said to be beneficial for those with cardiovascular problems.

When it comes to the risk of thinning bones, however, it's the weight-bearing nature of exercise that signals bones to create more mass. Without such stress, bones do not get stronger, and become more prone to injury.

The study found that competitive male road cyclists showed significantly lower bone mineral density in their spines than a control group of men who were moderately physically active.

Although the cyclists had a greater calcium intake, they were still more likely to have osteopenia and osteoporosis.

Another study had shown that male road cyclists had lower bone mineral density than male mountain bikers after adjusting for body weight and age.

Swimmers may also be at risk, because that sport requires similarly little mechanical loading, leaving the lower spine particularly vulnerable.

Cyclists and swimmers face another challenge in relation to bone density- caloric intake.

Both are known for burning up calories however, hard-core cyclists may not be eating enough to offset what they burn when they exercise, depriving their bodies of bone-strengthening nutrients such as calcium and vitamin D.