School of Social and Family Dynamics, Arizona State University, 951 S. Cady Mall, Tempe, AZ 85287, USA.
Int J Behav Nutr Phys Act. 2011 Apr 15;8:33. doi: 10.1186/1479-5868-8-33.
There is a rapid decline in moderate-to-vigorous physical activity (MVPA) during middle childhood and adolescence. Information on the environmental factors implicated in this decline is limited. This study focuses on family factors associated with the rate of decline in objectively measured physical activity during middle childhood and adolescence.
Longitudinal analysis of 801 participants from 10 US sites in the NICHD Study of Early Child Care and Youth Development whose data included accelerometer-determined levels of moderate-to-vigorous physical activity (MVPA) between ages 9 and 15 years, as well as family process, BMI and demographic information. The sample included an even split of boys (49%) and girls (51%), was predominantly white (77%), and contained about 26% low income and 19% single parent families. The outcome measure was mean MVPA. It was based on 4 to 7 days of monitored physical activity.
Boys with lower parental monitoring scores and more days of parental encouragement had significantly more minutes of MVPA at age 9 years. The effect of parental monitoring, however, was moderated by early puberty. High parental monitoring was associated with decreased activity levels for boys experiencing later puberty and increased activity for boy experiencing early puberty. Minutes of MVPA for boys living in the Midwest decreased at significantly faster rates than boys living in any other region; and boys in the South declined faster than boys in the West. Girls in the Midwest and South declined faster than girls in the West and Northeast. Among girls, more days of parental exercise and transportation to activities were associated with more MVPA per day at age 9. However, more parental transportation to activities and less monitoring was associated with faster linear declines in daughters' MVPA between the ages of 9 and 15 years. For girls who experienced puberty early, parental encouragement was associated with more MVPA.
Parenting processes, such as monitoring and encouragement, as well as the parents' own level of physical activity, showed significant, but small, gender-specific associations with MVPA levels at age nine and the linear rate of decline in MVPA between ages 9 and 15.
儿童中期和青少年时期的中度至剧烈体力活动（MVPA）迅速减少。关于导致这种减少的环境因素的信息有限。本研究重点关注与儿童中期和青少年时期客观测量体力活动下降速度相关的家庭因素。
对来自美国国立卫生研究院儿童早期照顾和青年发展研究中 10 个地点的 801 名参与者进行纵向分析，这些参与者的数据包括年龄在 9 至 15 岁之间的加速度计确定的中度至剧烈体力活动（MVPA）水平，以及家庭过程、BMI 和人口统计学信息。该样本包括 49%的男孩和 51%的女孩，主要是白人（77%），约 26%来自低收入家庭，19%来自单亲家庭。因变量是平均 MVPA。它基于 4 至 7 天的监测体力活动。
父母监控得分较低且父母鼓励天数较多的男孩在 9 岁时的 MVPA 分钟数明显更多。然而，父母监控的影响受到青春期早期的调节。对于经历青春期后期的男孩，高父母监控与活动水平降低有关，而对于经历青春期早期的男孩，高父母监控与活动水平增加有关。居住在中西部的男孩的 MVPA 分钟数以明显更快的速度下降，而居住在其他任何地区的男孩下降速度较慢；居住在南部的男孩下降速度快于居住在西部的男孩。居住在中西部和南部的女孩比居住在西部和东北部的女孩下降速度更快。在女孩中，每天有更多的父母锻炼和活动交通与 9 岁时每天更多的 MVPA 相关。然而，更多的父母交通活动和更少的监控与女儿 9 至 15 岁期间 MVPA 的线性下降速度更快相关。对于青春期早期的女孩，父母的鼓励与更多的 MVPA 相关。
父母养育方式，如监控和鼓励，以及父母自身的体力活动水平，与 9 岁时的 MVPA 水平和 9 至 15 岁期间 MVPA 的线性下降速度有显著但较小的性别特异性关联。
