Abstract：
Purpose: Youth sport (YS) is a community system for promoting children\'s physical activity (PA). Studies have examined mean PA during YS practices, but few have examined inequalities in the distribution of PA among children during practice time. This study examined PA inequality in time-segmented YS practices and differences in inequality by time segment characteristics. Methods: Children\'s PA and YS practices were examined using accelerometer and video observation data from a sample of YS teams (n = 36 teams, n = 101 practices) for third- through sixth-grade children (n = 392), approximately eight to 12 years old, in two rural U.S. communities. Practices were time-segmented into smaller units (episodes; n = 991). Episodes were assigned codes for purpose (e.g. warm-up), member arrangement (e.g. whole group), and setting demand (i.e. fosters participation, creates exclusion). Group accelerometer data were paired with episodes, and the Gini coefficient quantified inequality in activity counts and minutes of moderate-to-vigorous PA (MVPA). Beta generalized estimating equations examined the influence of episode structure on PA inequality. Results: Warm-up (Gini = 0.22), fitness (Gini = 0.24), and sport skill (Gini = 0.24) episodes had significantly lower inequality (p < .05) in activity counts than other purpose types. Management (Gini = 0.32) and strategy (Gini = 0.40) episodes had significantly greater inequality (p < .05) in MVPA minutes than other purpose types. Episodes fostering participation (Gini = 0.32) had significantly lower activity count inequality (p < .05) than episodes creating exclusion (Gini = 0.35). Conclusion: PA inequality among children during YS varied by practice structure. Metrics such as the Gini coefficient can illuminate inequalities in PA and may be useful for guiding efforts to improve population PA in children. Trial Registration: This study is registered at www.clinicaltrials.gov (Identifier: NCT03380143).
摘要：
目的：青少年体育（YS）是促进儿童体育活动（PA）的社区系统。研究已经检查了YS实践期间的平均PA，但很少有人研究在练习期间儿童中PA分布的不平等。这项研究检查了按时间分段的YS实践中的PA不平等以及按时间分段特征的不平等差异。方法：使用来自YS团队样本的加速度计和视频观察数据（n=36支团队，n=101种做法)，适用于三年级至六年级的儿童(n=392)，大约8到12岁，在美国的两个农村社区。实践被时间分割成较小的单位(发作;n=991)。为发作指定代码（例如热身），成员安排（例如整个小组），和设定需求(即促进参与，创建排除)。组加速度计数据与发作配对，基尼系数量化了中等至剧烈PA（MVPA）的活动计数和分钟数的不平等。β广义估计方程考察了事件结构对PA不等式的影响。结果：热身（Gini=0.22），fitness(Gini=0.24),与其他目的类型相比，运动技能（Gini=0.24）发作在活动计数上的不平等（p<.05）显着降低。与其他目的类型相比，管理（Gini=0.32）和策略（Gini=0.40）事件在MVPA分钟内的不平等（p<.05）明显更大。促进参与的发作（Gini=0.32）的活动计数不平等（p<.05）明显低于产生排斥的发作（Gini=0.35）。结论：YS期间儿童的PA不平等因练习结构而异。诸如基尼系数之类的指标可以阐明PA中的不平等，并且可能有助于指导改善儿童人口PA的努力。试用注册：本研究在www注册。clinicaltrials.gov（标识符：NCT03380143）。
