1Institute of Health Research, University of Exeter Medical School, Exeter, UNITED KINGDOM; 2Sport and Health Science, College of Life and Environmental Sciences, University of Exeter, Exeter, UNITED KINGDOM; and 3Department of Endocrinology and Metabolism, Peninsula Schools of Medicine and Dentistry, Plymouth University Plymouth, UNITED KINGDOM.
Med Sci Sports Exerc. 2015 Oct;47(10):2084-92. doi: 10.1249/MSS.0000000000000644.
Contemporary adolescents are deemed inactive, especially girls, but whether for biological reasons associated with their maturation, changes in their behavior or because of environmental constraints, is uncertain. We examined the trends in physical activity (PA) in relation to both biological and environmental factors in an attempt to establish what drives activity patterns from childhood through adolescence.
Physical activity (7-d Actigraph accelerometry) was measured annually from 5 to 15 yr in a single cohort of some 300 UK children. Total PA (TPA; in-school and out-of-school separately and combined as whole day) and intensity-specific PA (sedentary, light, and moderate-and-vigorous [MVPA]) were analyzed. Biological age (years before/after measured peak height velocity) and pubertal stage (self-reported pubic hair development-Tanner staging) were also measured as was socioeconomic status (postcode-derived index of multiple deprivation [IMD]).
Total PA was stable from 5 to 8 yr (trend P = 0.10) but fell progressively from 9 to 15 yr (by approximately 30% in girls and approximately 20% in boys, both P < 0.001; sex interaction, P < 0.01). Half of this fall was attributable to light intensity PA and only a quarter to MVPA. The decline in PA was related similarly to chronological and biological age, whereas pubertal stage explained the more rapid PA decline in girls (puberty-adjusted sex interaction, P = 0.51). Total PA fell to the same extent for in-school and out-of-school settings (both P < 0.001), and for lower and higher IMD areas (both P < 0.001). Total PA tracked moderately to strongly from childhood into adolescence (r = 0.58; P < 0.001).
The adolescent decline in PA is consistent across different environmental settings, attributable to falls in light-intensity/habitual activity and influenced by puberty, suggesting that the inactivity of adolescence may, in part, be under biological control.
当代青少年被认为是不活跃的，尤其是女孩，但无论是因为与成熟相关的生物学原因、行为变化还是因为环境限制，目前还不确定。我们研究了与生物学和环境因素相关的身体活动（PA）趋势，试图确定从儿童期到青春期是什么驱动了活动模式。
在一个由大约 300 名英国儿童组成的单一队列中，每年使用 7 天的 Actigraph 加速度计测量身体活动（PA）。总 PA（PA；在学和校外分别以及合并为全天）和强度特异性 PA（久坐、轻度和中等到剧烈[MVPA]）进行分析。还测量了生物年龄（测量的峰值身高速度之前/之后的年数）和青春期阶段（自我报告的阴毛发育- Tanner 分期）以及社会经济地位（邮政编码衍生的多重剥夺指数[IMD]）。
总 PA 从 5 岁到 8 岁保持稳定（趋势 P = 0.10），但从 9 岁到 15 岁逐渐下降（女孩下降约 30%，男孩下降约 20%，均 P < 0.001；性别交互作用，P < 0.01）。下降的一半归因于轻度活动强度，只有四分之一归因于 MVPA。PA 的下降与年龄和生物年龄的相关性相似，而青春期阶段解释了女孩 PA 下降更快（青春期调整后的性别交互作用，P = 0.51）。学校内外的 PA 下降程度相同（均 P < 0.001），低 IMD 地区和高 IMD 地区的 PA 下降程度相同（均 P < 0.001）。PA 从儿童期到青春期呈中度至高度稳定（r = 0.58；P < 0.001）。
PA 在青少年中的下降在不同的环境设置中是一致的，归因于轻强度/习惯性活动的下降，并且受到青春期的影响，这表明青少年的不活跃可能部分受到生物控制。
