Exercise in Youth and Long-Term Effects on Bone and Joints
Summary, in English
We evaluated bone traits in two studies. The first was a 39-year prospective cohort study that followed 46 active male athletes into a mean 29 years of retirement and 24 age-matched controls. The second used a cross-sectional mixed model design that included 329 measurements in 193 active and former male soccer players and 450 measurements in 280 controls, all aged between 18 and 85 years. The first study measured BMD by single-photon absorptiometry (SPA) on both occasions, and with dual energy X-ray absorptiometry (DXA), peripheral computed tomography (pQCT) and quantitative ultrasound (QUS) at follow-up. The second study used DXA. Fracture incidence was evaluated in two retrospective cohort studies, one including 397 former male soccer players and 1368 age-matched controls and the second 709 former male athletes in a variety of sports and 1368 age-matched controls. The prevalence of hip and knee OA and arthroplasty was also evaluated in the second study.
In the first study we found no changes in relative leg BMD levels [Δ Z-score 0.0 (95% CI –0.4, 0.4)] in athletes from activity into retirement. At follow-up, former athletes still had 0.5 to 1.2 standard deviations (SD) higher BMD, bone size, and strength index than controls (all p<0.05). In the second study, total body BMD, leg BMD, and femoral neck area were 0.3 to 0.5 SD higher in 30 or more years retired athletes than in controls (all p<0.05). Former male athletes had a 50% [RR 0.5 (95% CI 0.3, 0.9)] and former soccer players had a 60% [RR 0.4 (95% CI 0.2, 0.9)] lower risk respectively of any fragility fracture incidence than controls (both p<0.05), and two times higher age-adjusted risk of a hip and/or knee OA [OR 1.9 (95% CI 1.5, 2.3)], as well as a hip and/or knee arthroplasty [OR 2.2 (95% CI 1.6, 3.1)]. After adjustment for differences in BMI, occupational load, and previous soft tissue knee injury, there was no increased risk of knee OA in former impact athletes while the risk remained in non-impact athletes [OR 3.2 (95% CI 1.5, 6.9)].
This thesis infers that exercise-associated benefits in BMD and bone size remain long-term after sports, and that former athletes are at lower fracture risk than controls. In contrast, the risk of hip and/or knee OA and THA and/or TKA is higher in former athletes than in controls. The higher risk of knee OA in former athletes is associated with a knee injury in impact but not in non-impact athletes.
Lund University Faculty of Medicine Doctoral Dissertation Series
Department of Clinical Sciences, Lund University
- Clinical Medicine
- bone mass
- bone geometry
- bone size
- former athletes
- fragility fracture
- knee injury
- hip injury
- total joint replacement
- ISSN: 1652-8220
- ISBN: 978-91-87449-20-8
8 May 2013
Lilla Aulan, Medicinskt forskningscemtrum, SUS, Malmö
- Jan Ekstrand (professor)