有氧运动对超重青少年骨密度的影响

Effect of aerobic exercise on bone mineral density in overweight adolescents

目的分析青少年体成分与骨密度的关系,探讨生活方式干预对超重青少年骨密度及体成分的影响。方法选取北京市城区1所中学共117名健康青少年,年龄11.08～15.17岁,男:女54:63,进行人体测量学指标测定,使用双能X光吸收仪测定骨密度(BMD)、肌肉质量及脂肪比率。受试者按BMI分为正常体重组(30人)和超重组(87人)。超重组(BMI:22.4～34.09kg/m2)按干预方式被随机分为饮食组(D)、运动组(EX)、饮食加运动组(DEX)及对照组(C),进行10周干预。干预结束后复测上述指标。结果女生BMD显著高于男生(P<0.01),未发育者BMD较已发育者低(P<0.05),正常体重组与超重组间BMD差异无统计学意义(P>0.05)。BMD与年龄、身高、体重、BMI、胸围、臀围、全身肌肉质量呈正相关(r=0.206～0.329,P<0.05);与腰围、全身及躯干体脂率无明显相关性(P>0.05)。干预后D、EX及DEX组体重、BMI、腰围、臀围、WHR均显著下降,与干预前比较差异有统计学意义(P<0.01),C组体重和BMI无明显变化(P>0.05);D、EX及DEX组干预后全身及各部位脂肪含量均显著下降(P<0.01);EX组及DEX组BMD均显著增加(P<0.01,P<0.05),D组及C组BMD无明显变化(P>0.05)。(EX+DEX)组BMD平均增加(0.017±0.027)g/cm2,明显高于非运动组(D+C)BMD平均变化(0.008±0.047)g/cm2(P<0.01);而饮食干预组(D+DEX)组与非饮食干预组(EX+C)组BMD差异无统计学意义(P>0.05)。结论青少年阶段骨密度随年龄、身高和体重的增加而增加,并存在性别差异。骨密度增加与机体肌肉质量呈正相关,与脂肪比率无明显关系。有效的饮食和运动干预均可减轻体重和脂肪比率,运动可促进骨密度增加。对超重青少年应积极进行包括有氧运动在内的生活方式干预。

Objective To analyze the relationship between body composition and bone mineral density in adolescents, and explore the influence of lifestyle intervention on bone mineral density and body composition in overweight adolescents.Methods 117 healthy adolescents （age 11.08-15.17 years, male： female 54：63） were recruited from a high school in urban area of Beijing. Anthropometry data were measured. Bone mineral density （BMD）, body muscle mass and body fat percentage were measured by dual-energy X-ray absorptiometry（DEXA）. According to BMI, subjects were divided into normal weight group（n=30） and overweight group（n=87）. Overweight subjects（BMI 22.4~34.09 kg/m2） were randomly assigned to four groups： diet （D）, exercise（EX）, diet plus exercise（DEX）, and overweight control （C）. After 10 weeks of diet or aerobic exercise intervention, changes of those indicators were determined.Results BMD of girls was significantly higher than that of boys（P0.01）. Subjects in puberty had higher BMD than that in prepuberty（P0.05）. No significant difference was observed between normal weight and overweight group（P0.05）. BMD was positively correlated with age, height, weight, BMI, chest circumference, hip circumference, whole body muscle mass（r=0.206~0.329,P0.05）, and was not significantly correlated with waist circumference, body and trunk fat rates（P0.05）. After the intervention, body and truncal fat rates were significantly decreased in group D, EX and DEX（P0.01）, BMD in group EX（P0.01） and DEX（P0.05） were significantly increased, while no significant changes of BMD were observed in group D and C（P0.05）. The average increase in BMD of exercise groups （EX＋DEX）[（0.017±0.027） g/cm2] was significantly higher than that of non-exercise groups （D＋C） [（0.008±0.047）g/cm2]（P0.01）. However, there was no significant difference between changes in BMD of dietary group （D＋DEX） and non-dietary group （EX＋C） （P0.05）. Conclusion In adolescence, BMD increases with age, height and weight, and has gender difference. BMD is positively correlated with muscle mass, but is not correlated with fat rate. Both effective diet and exercise intervention can reduce body weight and fat, but only exercise can promote BMD increase. Overweight adolescents should take lifestyle intervention including aerobic exercises.