Moderate‐to‐vigorous‐intensity physical activity (MVPA) is important for childhood obesity prevention and treatment, yet declines with age. Timing and magnitude of the decline in MVPA in children and adolescents are unclear but important for informing effective obesity intervention development. This systematic review aimed to determine and compare the year‐to‐year changes in MVPA among children and adolescents. Longitudinal studies were identified by searching 10 relevant databases up to December 2018. Studies were eligible for inclusion if they reported accelerometer‐assessed MVPA (min day⁻¹) separately for boys and girls and had follow‐up duration of at least 1 year. After screening 9,232 studies, 52 were included representing 22,091 aged 3 to 18 year olds (boys=8,857; girls=13,234). Pooled‐analysis of the relative change in MVPA per year showed a decline of −3.4% (95% CI, −5.9 to −0.9) in boys and −5.3% (95% CI, −7.6 to −3.1) in girls, across all age groups. There were notable declines in MVPA at age 9 for both boys (−7.8%, 95% CI, −11.2 to −4.4) and girls (−10.2%, 95% CI, −14.2 to −6.3). The relative decline in MVPA affects both sexes from an early age; however, it is greater among girls. Interventions to promote MVPA should start before adolescence.

中文翻译：

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儿童和青少年中度至剧烈强度体育活动的纵向变化：系统评价和荟萃分析。

中度至剧烈运动强度（MVPA）对儿童肥胖症的预防和治疗很重要，但随着年龄的增长而下降。儿童和青少年MVPA下降的时间和幅度尚不清楚，但对于告知有效的肥胖症干预发展很重要。该系统评价旨在确定和比较儿童和青少年中MVPA的逐年变化。截至2018年12月，通过搜索10个相关数据库确定了纵向研究。如果研究报告了加速计评估的MVPA（至少^-1天，则可纳入研究））分别针对男孩和女孩，且随访时间至少为1年。筛选了9,232项研究后，纳入了52项研究，代表22,091名3至18岁的年龄段（男孩= 8,857；女孩= 13,234）。汇总分析每年MVPA的相对变化表明，男孩的下降幅度为-3.4％（95％CI，-5.9至-0.9），女孩的下降幅度为-5.3％（95％CI，-7.6至-3.1）。所有年龄段的人。男孩（−7.8％，95％CI，-11.2至-4.4）和女孩（−10.2％，95％CI，-14.2至-6.3）的9岁时MVPA均显着下降。MVPA的相对下降从小就影响到男女。但是，女孩中的比例更高。促进MVPA的干预措施应在青春期之前开始。