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.
These caloric shortfalls could also trigger physiological problems such as lower levels of estrogen in women and testosterone in men, both hormones that have protective effects on bones and slow the rate of bone breakdown.
"Unfortunately, many people consider osteoporosis a disease that primarily concerns women and the elderly," said Dr. Warren P. Levy, President, and CEO of Unigene Laboratories.
"Of course, exercise is good for people, but in order to maintain healthy bones, avid cyclists and swimmers should be mindful of incorporating cross-training weight-bearing exercise into their routines.
People do not achieve peak bone mass until their late twenties, so if cyclists or swimmers are in their early or mid twenties, and they're not doing any exercise that's going to load their spine and help them achieve peak bone mass, they may be putting themselves at risk for a fracture," he added.
The study appears in Medicine and Science in Sports and Exercise.