title: Bone gains and losses follow seasonal training and detraining in gymnasts.
abstract: The response of the human skeleton to high magnitude loading and unloading is poorly understood. Our aim was to evaluate changes in bone mineral density (BMD) in a group of intercollegiate gymnasts (n = 8, age = 18.6+/-0.8 years) over 24 months that included two 8-month competitive seasons and two 4-month offseasons. BMD of the hip, spine, and whole body was evaluated by DXA (Hologic QDR-1000/W) at baseline, 8, 12, 20, and 24 months. Results indicated significant seasonal trends in BMD of the femoral neck, trochanter, total hip, lumbar spine, and whole body. Specifically, there was a strikingly consistent pattern of bone density increases over the training seasons followed by clear declines in the offseasons. Increases at the spine were 3.5% and 3.7% followed by declines of 1.5% and 1.3% in the offseasons. Total hip BMD increased 2.3% and 1.9% during the competitive seasons followed by decreases of 1.5% and 1.2% in the offseasons. We observed a significant 24-month increase of 4.3% in spine BMD but no significant overall change at the hip. In conclusion, the human skeleton demonstrated a measurable response to high magnitude loading and unloading that was consistent across bone sites over 24 months of observation.
authors.affiliation: Bone Research Laboratory, Oregon State University, Corvallis 97331, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Snow
authors.forename: D P
authors.initials: DP
authors.lastname: Williams
authors.forename: J
authors.initials: J
authors.lastname: LaRiviere
authors.forename: R K
authors.initials: RK
authors.lastname: Fuchs
authors.forename: T L
authors.initials: TL
authors.lastname: Robinson
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D001835:Body Weight / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D016723:Bone Remodeling / Q000502:physiology*; D001842:Bone and Bones / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006173:Gymnastics / Q000502:physiology*; D006801:Humans; D008597:Menstrual Cycle; D012621:Seasons; D016474:Weight-Bearing / Q000502:physiology