BACKGROUND Early experiences in physical activity (PA) are important to shape healthy movement behaviours long-term; as such, it is critical that PA is promoted from infancy, and that detrimental behaviours (e.g., prolonged sedentary time [ST]) are minimized. The purpose of this systematic review and meta-analysis was to examine infants' and toddlers' movement behaviours across daytime hours. METHODS Seven online databases were searched for terms related to infants (< 12 months), toddlers (12-35.9 months), PA, ST, and accelerometry. Two independent reviewers examined 4873 articles for peer-reviewed original research, published in English, that assessed infants' (counts/min) and/or toddlers' PA or ST (min/day) using accelerometry across daytime hours. Infants' mean PA level (counts/min) was averaged across studies, and ranges were produced. Estimates of toddlers' movement behaviours were aggregated meta-analytically to produce average daily rates, and accelerometer placement, cut-point validity, device type, and epoch length were tested as a moderating variables. RESULTS Twenty-four studies from 16 countries (published 2011-2019), representing 3699 participants, were included in the systematic review. Five studies reported on infants' PA, which ranged from 78.2 to 2580.5 cpm. Across 20 studies, toddlers' total PA, light PA, moderate-to vigorous-intensity PA, and ST ranged from 72.9 to 636.5, 48.5 to 582.4, 6.5 to 89.9, and 172.7 to 545.0 min/day, respectively. After taking into account accelerometer placement, cut-point validity, device type, and epoch length, we found that toddlers engaged in 246.19 min/day (SE = 28.50; 95% CI: 190.34, 302.04) of total PA, 194.10 min/day (SE = 28.76; 95% CI: 137.73, 250.47) of light PA, and 60.16 min/day (SE = 5.88; 95% CI: 48.64, 71.69) of moderate-to vigorous-intensity PA. Toddlers engaged in 337.04 min/day (SE = 32.67; 95% CI: 273.01, 401.07) of ST. CONCLUSIONS With limited studies conducted in infants (n = 5), PA estimates are inconclusive and largely heterogeneous. Overall, toddlers tend to exceed the total PA recommendation of 180 min/day; however, very little of this time is spent at higher movement intensities. Even with high PA rates, toddlers still engage in substantial ST. More consistent and valid measurement protocols are needed to improve comparability across studies.

中文翻译：

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通过加速度测量测量婴儿和幼儿的身体活动和久坐时间：系统评价和荟萃分析。

背景 早期的体力活动 (PA) 经历对于塑造长期健康的运动行为非常重要。因此，从婴儿期开始促进 PA 并尽量减少有害行为（例如，延长久坐时间 [ST]）至关重要。这项系统评价和荟萃分析的目的是检查婴儿和幼儿在白天的运动行为。方法 搜索七个在线数据库，查找与婴儿（< 12 个月）、幼儿（12-35.9 个月）、PA、ST 和加速度测量相关的术语。两名独立评审员审查了 4873 篇同行评审的原创研究文章，这些文章以英文发表，使用白天的加速度测量法评估婴儿（计数/分钟）和/或幼儿的 PA 或 ST（分钟/天）。婴儿的平均 PA 水平（计数/分钟）是各个研究的平均值，并产生了范围。对幼儿运动行为的估计通过元分析进行汇总，以产生平均每日速率，并测试加速度计的放置、切点有效性、设备类型和历元长度作为调节变量。结果 系统评价纳入了来自 16 个国家的 24 项研究（2011-2019 年发表），代表 3699 名参与者。五项研究报告了婴儿的 PA，范围为 78.2 至 2580.5 cpm。在 20 项研究中，幼儿的总 PA、轻度 PA、中度至高强度 PA 和 ST 范围分别为 72.9 至 636.5、48.5 至 582.4、6.5 至 89.9 和 172.7 至 545.0 分钟/天。考虑到加速度计的放置、切点有效性、设备类型和历元长度后，我们发现幼儿每天的活动时间为 246.19 分钟（SE = 28.50；95% CI：190.34, 302.04），占总 PA 时间的 194.10 分钟/天(SE = 28.76; 95% CI: 137.73, 250.47) 轻度 PA，以及 60.16 分钟/天 (SE = 5.88; 95% CI: 48.64, 71.69) 中度至高强度 PA。幼儿每天进行 337.04 分钟的 ST（SE = 32.67；95% CI：273.01, 401.07）。结论 由于对婴儿 (n = 5) 进行的研究有限，PA 估计值尚无定论，且很大程度上异质性。总体而言，幼儿往往会超过每日 180 分钟的总 PA 建议时间；然而，这段时间很少花在较高的运动强度上。即使 PA 率很高，幼儿仍然会进行大量的 ST。需要更一致和有效的测量方案来提高研究之间的可比性。