PhD defence Luuk Petrus Maria Hilkens

Keywords: 
Bone health, Elite cyclists, Collagen supplementation, Impact exercise

"Exercise and nutritional strategies to promote bone health in elite cyclists"

Mechanical loading of the skeleton is essential for the development and maintenance of bone mass. Non–weight-bearing sports, such as cycling, lack substantial mechanical loading, and, therefore, provide little benefit for bone. Indeed, this thesis revealed a high prevalence of low bone mineral density (BMD) among elite cyclists. Low BMD was also associated with an increased fracture incidence during the active career. Consistent predictors of low BMD in elite cyclists included a lack of prior participation in bone-specific mechanical loading activities, along with markers of low energy availability, such as serum total triiodothyronine (T3) levels and body mass index (BMI). In addition, high-resolution peripheral quantitative computed tomography (HR-pQCT) revealed a high prevalence of low volumetric BMD and impaired bone microarchitecture and geometry.

This PhD research subsequently showed that multi-directional jumping exercise combined with collagen supplementation during the off-season period is both feasible and effective in preserving BMD at the hip region in elite cyclists. However, another study in this thesis showed that the serum marker of bone formation procollagen type I N propeptide (P1NP) increased following brief jumping exercise, but with no further increase following collagen supplementation when compared to a placebo.

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