Vicente-Rodríguez G, Ortega F B, Rey-López J P, España-Romero V, Blay V A, Blay G, Martín-Matillas M, Moreno L A
Growth, Exercise, Nutrition and Development (GENUD) research group, Zaragoza, Spain.
Bone. 2009 Nov;45(5):925-30. doi: 10.1016/j.bone.2009.07.084. Epub 2009 Aug 5.
To examine whether different sedentary behaviours are associated with the risk of low bone mineral content in adolescents, and if so, whether extracurricular physical-sporting activity influences this association.
A total of 277 adolescents from Zaragoza (168 females and 109 males) aged 13.0-18.5 yr within frame work of the multicentre AVENA study participated in this study. Bone mineral content (BMC), lean mass, and fat mass were measured with DXA. Physical activity and sedentary independent variables: participation in extracurricular physical-sporting activity (PA), h/d of television watching, playing video/computer games during school days and on weekend days and doing homework/studying. They all were assessed by questionnaire. The main outcome was low BMC, as defined by BMC Z-score for age and sex < percentile 10. Logistic regression was used to test the interaction and association of PA and sedentary variables with low BMC, after controlling for confounders like height, maturational status or lean mass.
Among the sedentary variables studied, only television watching > or =3 h/d was associated with an increased risk for low BMC in males (OR, 95% CI: 7.01, 1.73 to 28.40), after controlling for sexual maturation. When PA was in the models, television watching was not any longer associated with low BMC, while PA was so (OR, 95% CI: 0.23, 0.09 to 0.55). Involvement in such activity reduced the risk of low bone mass by 76% (P<0.01) independently of body mass, height and fat mass, but not of the lean mass.
Watching television for 3 or more h/d seems to be associated with an increased risk for low BMC in male adolescents. However, this association is mediated by participation in PA, suggesting that negative consequences of excessive television watching on adolescent bone health could be counteracted by sport participation. Longitudinal data and randomized controlled trials will confirm or contrast our findings.
研究不同久坐行为是否与青少年低骨矿物质含量风险相关，若相关，课外体育活动是否会影响这种关联。
在多中心AVENA研究框架内，共有277名来自萨拉戈萨的青少年（168名女性和109名男性），年龄在13.0 - 18.5岁之间参与了本研究。使用双能X线吸收法测量骨矿物质含量（BMC）、瘦体重和脂肪量。身体活动和久坐独立变量：参与课外体育活动（PA）、每天看电视的小时数、上学日和周末玩电子游戏/电脑游戏以及做作业/学习的情况。这些均通过问卷调查进行评估。主要结局为低BMC，定义为按年龄和性别划分的BMC Z评分低于第10百分位数。在控制了身高、成熟状态或瘦体重等混杂因素后，使用逻辑回归来检验PA和久坐变量与低BMC的相互作用和关联。
在所研究的久坐变量中，在控制了性成熟因素后，仅每天看电视≥3小时与男性低BMC风险增加相关（比值比，95%置信区间：7.01，1.73至28.40）。当PA纳入模型时，看电视不再与低BMC相关，而PA则相关（比值比，95%置信区间：0.23，0.09至0.55）。参与此类活动可使低骨量风险降低76%（P<0.01），独立于体重、身高和脂肪量，但不独立于瘦体重。
每天看电视3小时或更长时间似乎与男性青少年低BMC风险增加相关。然而，这种关联由参与PA介导，表明过度看电视对青少年骨骼健康的负面影响可通过参与运动来抵消。纵向数据和随机对照试验将证实或对比我们的发现。
