Matthews B L, Bennell K L, McKay H A, Khan K M, Baxter-Jones A D G, Mirwald R L, Wark J D
Centre for Health, Exercise and Sports Medicine School of Physiotherapy, The University of Melbourne, Melbourne, Victoria 3010, Australia.
Osteoporos Int. 2006;17(7):1043-54. doi: 10.1007/s00198-006-0093-2. Epub 2006 Apr 14.
Weight-bearing exercise during growth enhances peak bone mass. However, the window of opportunity for optimizing positive effects of exercise on peak bone mass remains to be fully defined. Ballet dancing provides a model of mechanical loading patterns required to site-specifically modulate bone.
We assessed the effects of ballet dancing on bone mineral accrual in female non-elite dancers and normally active controls for 3 years across puberty. We recruited 82 ballet dancers and 61 controls age 8-11 years at baseline. Participants were measured over 3 consecutive years; however, the overlap in ages allowed analysis of the groups across 8-14 years of age. We annually assessed bone mineral content (BMC) at the total body (TB), including upper and lower limb regions, and biannually assessed BMC at the proximal femur and lumbar spine (LS) using dual x-ray absorptiometry (DXA). We derived TB lean mass and fat mass from DXA TB scans. Anthropometry, exercise levels, and calcium intake were also measured biannually. Maturational age was determined by age at peak height velocity (PHV). A multilevel regression model was used to determine the independent effects of body size, body composition, maturation, exercise levels, and calcium intake at each measurement occasion.
When adjusted for growth and maturation, dancers had significantly greater BMC at the TB, lower limbs, femoral neck (FN), and LS than controls. Excepting the FN region, these differences became apparent at 1 year post-PHV, or the peripubertal years, and by 2 years post-PHV the differences represented a cumulative advantage in dancers of 0.6-1.3% (p<0.05) greater BMC than controls. At the FN, dancers had 4% (p<0.05) greater BMC than controls in prepuberty and maintained this advantage throughout the pubertal years.
Results from this novel population provide evidence for modest site-specific and maturity-specific effects of mechanical loading on bone.
生长期间的负重运动可提高峰值骨量。然而，优化运动对峰值骨量的积极影响的机会窗口仍有待充分确定。芭蕾舞提供了一种针对特定部位调节骨骼所需的机械负荷模式模型。
我们评估了芭蕾舞对青春期3年期间非精英女性舞者和正常活动对照组骨矿物质积累的影响。我们招募了82名8 - 11岁的芭蕾舞舞者和61名对照组作为基线。参与者连续3年接受测量；然而，年龄重叠使得可以对8 - 14岁的两组进行分析。我们每年使用双能X线吸收法（DXA）评估全身（TB），包括上肢和下肢区域的骨矿物质含量（BMC），并每半年评估一次股骨近端和腰椎（LS）的BMC。我们从DXA的TB扫描中得出TB瘦体重和脂肪量。每半年还测量人体测量学指标、运动水平和钙摄入量。成熟年龄通过身高增长峰值速度（PHV）时的年龄来确定。使用多级回归模型来确定每次测量时身体大小、身体成分、成熟度、运动水平和钙摄入量的独立影响。
在对生长和成熟进行调整后，舞者在TB、下肢、股骨颈（FN）和LS处的BMC显著高于对照组。除FN区域外，这些差异在PHV后1年即青春期前后变得明显，到PHV后2年，这些差异表明舞者的BMC比对照组累积高出0.6 - 1.3%（p<0.05）。在FN处，舞者在青春期前的BMC比对照组高4%（p<0.05），并在整个青春期保持这一优势。
来自这个新人群的结果为机械负荷对骨骼的适度部位特异性和成熟度特异性影响提供了证据。
