The purpose of this study was to evaluate the bone status in highly trained professional cyclists subjected to regular training and tough competitions. Bone mineral density (BMD) was measured at different regions of interest by dual X-ray absorptiometry and main biological parameters related to bone metabolism were obtained in 29 cyclists. Lumbar BMD was 0.94±0.01 g/cm² (Z score=-1.28±0.07) and 1 cyclist out of 4 had and abnormally low value (Z-score <-2). The mean Z score at the total femoral site was-1.22±0.21 and 45% of athletes had a Z-score <-2. All femoral neck BMD values were within normal boundaries. The lowest BMD Z-score were measured at the mid radius or 1/3 proximal site with a mean Z-score of-1.77±0.78 but only 3 cyclists (15%) had Z-scores <-2. Biochemical parameters of bone formation, (serum ostéocalcine, and alkaline phosphatase) were normal. Three cyclists had low 25(OH) vitamin D levels. Blood testosterone and TSH were in the normal range. IGF-I levels were in the normal range; however, a significant inverse correlation was found with lumbar BMD (r=0.495; p=0.003). We confirm that cycling has no positive effect on BMD; BMD being often lower than in normal controls at the lumbar site; femoral BMD is less concerned. Absence of beneficial changes at the spine can be explained by biomechanical conditions related to the cyclists' position, reducing loading strains. It is necessary to pay greater attention to the bone status of high level athletes to prevent an increased risk of fractures.

The purpose of this study was to evaluate the bone status in highly trained professional cyclists subjected to regular training and tough competitions. Bone mineral density (BMD) was measured at different regions of interest by dual X-ray absorptiometry and main biological parameters related to bone metabolism were obtained in 29 cyclists. Lumbar BMD was 0.94±0.01 g/cm² (Z score= -1.28±0.07) and 1 cyclist out of 4 had and abnormally low value (Z-score <-2). The mean Z score at the total femoral site was -1.22±0.21 and 45% of athletes had a Z-score <-2. All femoral neck BMD values were within normal boundaries. The lowest BMD Z-score were measured at the mid radius or 1/3 proximal site with a mean Zscore of -1.77±0.78 but only 3 cyclists (15%) had Z-scores <-2. Biochemical parameters of bone formation, (serum ostéocalcine, and alkaline phosphatase) were normal. Three cyclists had low 25(OH) vitamin D levels. Blood testosterone and TSH were in the normal range. IGF-I levels were in the normal range; however, a significant inverse correlation was found with lumbar BMD (r=0.495; p=0.003). We confirm that cycling has no positive effect on BMD; BMD being often lower than in normal controls at the lumbar site; femoral BMD is less concerned. Absence of beneficial changes at the spine can be explained by biomechanical conditions related to the cyclists' position, reducing loading strains. It is necessary to pay greater attention to the bone status of high level athletes to prevent an increased risk of fractures.