Jiménez-Pavón David, Fernández-Vázquez Amaya, Alexy Ute, Pedrero Raquel, Cuenca-García Magdalena, Polito Angela, Vanhelst Jérémy, Manios Yannis, Kafatos Anthony, Molnar Dénes, Sjöström Michael, Moreno Luis A
GENUD (Growth, Exercise, Nutrition and Development), Department of Physiotherapy and Nursing, Research Group, Faculty of Health Sciences, University of Zaragoza, Avd, Domingo Miral s/n, CP: 50009, Zaragoza, Spain.
BMC Public Health. 2013 Jul 18;13:667. doi: 10.1186/1471-2458-13-667.
Physical activity (PA) is suggested to contribute to fat loss not only through increasing energy expenditure "per se" but also increasing muscle mass; therefore, it would be interesting to better understand the specific associations of PA with the different body's components such as fat mass and muscle mass. The aim of the present study was to examine the association between objectively measured PA and indices of fat mass and muscle components independently of each other giving, at the same time, gender-specific information in a wide cohort of European adolescents.
A cross-sectional study in a school setting was conducted in 2200 (1016 males) adolescents (14.7 ± 1.2 years). Weight, height, skinfold thickness, bioimpedance and PA (accelerometry) were measured. Indices of fat mass (body mass index, % fat mass, sum of skinfolds) and muscular component (assessed as fat-free mass) were calculated. Multiple regression analyses were performed adjusting for several confounders including fat-free mass and fat mass when possible.
Vigorous PA was positively associated with height (p<0.05) in males, whilst, vigorous PA, moderate-vigorous PA and average PA were negatively associated with all the indices of fat mass (all p<0.01) in both genders, except for average PA in relation with body mass index in females. Regarding muscular components, vigorous PA showed positive associations with fat-free mass and muscle mass (all p<0.05) in both genders. Average PA was positively associated with fat-free mass (both p<0.05) in males and females.
The present study suggests that PA, especially vigorous PA, is negatively associated with indices of fat mass and positively associated with markers of muscle mass, after adjusting for several confounders (including indices of fat mass and muscle mass when possible). Future studies should focus not only on the classical relationship between PA and fat mass, but also on PA and muscular components, analyzing the independent role of both with the different PA intensities.
体育活动（PA）被认为不仅通过增加“本身”的能量消耗，还通过增加肌肉量来促进脂肪减少；因此，更好地理解PA与身体不同组成部分（如脂肪量和肌肉量）之间的具体关联将很有意思。本研究的目的是在大量欧洲青少年队列中，独立研究客观测量的PA与脂肪量和肌肉组成指标之间的关联，同时给出性别特异性信息。
在学校环境中对2200名青少年（1016名男性）进行了横断面研究（年龄14.7±1.2岁）。测量了体重、身高、皮褶厚度、生物电阻抗和PA（加速度计）。计算了脂肪量指标（体重指数、体脂百分比、皮褶总和）和肌肉组成指标（以去脂体重评估）。进行了多元回归分析，并尽可能对包括去脂体重和脂肪量在内的多个混杂因素进行了调整。
在男性中，剧烈PA与身高呈正相关（p<0.05），而在两性中，剧烈PA、中等强度剧烈PA和平均PA与所有脂肪量指标均呈负相关（所有p<0.01），女性中平均PA与体重指数的关系除外。关于肌肉组成，剧烈PA在两性中与去脂体重和肌肉量均呈正相关（所有p<0.05）。平均PA在男性和女性中均与去脂体重呈正相关（两者p<0.05）。
本研究表明，在对多个混杂因素（尽可能包括脂肪量和肌肉量指标）进行调整后，PA，尤其是剧烈PA，与脂肪量指标呈负相关，与肌肉量指标呈正相关。未来的研究不仅应关注PA与脂肪量之间的经典关系，还应关注PA与肌肉组成之间的关系，分析不同PA强度下两者的独立作用。
