Exercise is widely touted for its health benefits, but for cyclists, particularly those competing at a high level, it can present a hidden risk: diminished bone density. While seemingly counterintuitive, the repetitive, non-weight-bearing nature of cycling can weaken bones over time, leaving athletes vulnerable to fractures. The issue is often silent, with few or no symptoms appearing until a break occurs, making preventative measures crucial.
The human skeleton isn’t simply inert mineral structures. Bones are dynamic tissues, constantly being broken down and rebuilt by specialized cells called osteoblasts (which create new bone) and osteoclasts (which break down bone tissue). The outer layer of bone, cortical bone, provides strength and structure, while the inner, spongy cancellous bone houses bone marrow responsible for blood cell production. Maintaining a balance between these processes is vital for bone health.
Bone strength peaks in early adulthood – in women in their early 20s and men in their late 20s – and is heavily influenced by early diet and exercise. Weight-bearing activities stimulate osteoblasts, encouraging bone growth. The body also relies on calcium stored in bones to fuel muscle contractions, maintaining what’s known as calcium homeostasis. For women, estrogen plays a critical role in bone maintenance, and its decline during menopause can accelerate bone loss.
Pro Cycling’s Unique Challenge
The problem for cyclists lies in the mechanics of the sport. Unlike running, jumping, or weightlifting, cycling doesn’t consistently impose significant impact or weight-bearing stress on the bones. Even during intense efforts like sprinting or climbing, the forces aren’t sufficient to stimulate the bone-building processes. Recovery from hard cycling often involves rest and reduced activity, further limiting weight-bearing stimulus.
Research published in 2023 by Spanish researchers, detailed in the journal Nutrients, underscored this concern. The study followed 18 professional cyclists over a single season, measuring their bone health before and after racing at least one Grand Tour. The results showed a measurable decline in bone mineral density across the group, corroborating earlier findings on cyclists and swimmers. This suggests that even a single season of intense cycling can negatively impact bone health.
Historically, professional cycling culture has inadvertently exacerbated the problem. A focus on minimizing weight, often through calorie restriction, and a discouragement of weight training or impact sports during the racing season, created conditions that were detrimental to bone health. However, awareness is growing, and teams are beginning to prioritize bone health alongside performance.
Therese Hammerschmith, Head of Performance at Human Powered Health, emphasizes the importance of proactive assessment. “That’s something I’m really proud of our team for prioritizing the health of the athletes first,” she said. The team utilizes comprehensive testing, including DEXA scans, to establish baseline bone density and monitor changes over time. This data informs individualized training and nutrition plans designed to mitigate risk.
Hammerschmith notes that simply screening for bone density isn’t enough. “We need to take each individual as they are and make sure that we’re fueling their individual physiology for their best outcomes, for success, both on the performance side as well as the health side.”
Mitigating the Risks
While some risk factors for osteoporosis, such as genetics, ethnicity, and gender, are unchangeable, many are within an athlete’s control. A poor diet during childhood can establish a lower baseline bone density, but this can be addressed with improved nutrition throughout life. Avoiding smoking and excessive alcohol consumption are also important. Underlying medical conditions like celiac disease or inflammatory bowel disease, which can interfere with nutrient absorption, must be properly managed.
Perhaps the most critical factor is energy availability. Chronic calorie restriction, leading to a condition known as Relative Energy Deficiency in Sport (RED-S), disrupts hormonal balance and can significantly impair bone health. RED-S, formerly known as the “female athlete triad,” affects both men and women, though symptoms can be more subtle in males.
To counteract the bone-weakening effects of cycling, athletes can incorporate weight-bearing exercises into their training regimen. Adding runs, plyometrics (jump training), and strength training can stimulate osteoblast activity and promote bone growth. Some research suggests that consuming calcium-rich foods or supplements before exercise may also help reduce calcium loss from bones during strenuous activity.
The lessons learned from professional cycling extend beyond elite athletes. Anyone who engages in prolonged, non-weight-bearing exercise should be mindful of their bone health. Prioritizing a balanced diet, ensuring adequate calorie intake, and incorporating regular weight-bearing activity are essential steps to maintaining strong, resilient bones throughout life.
