a Movement Behaviours, Health, and Wellbeing Research Group, Department of Sport and Physical Activity , Edge Hill University , Ormskirk , UK.
b Department of Physical Education and Sports Sciences , University of Limerick , Limerick , Ireland.
J Sports Sci. 2019 Sep;37(18):2159-2167. doi: 10.1080/02640414.2019.1624313. Epub 2019 Jun 1.
Average acceleration (AvAcc) and intensity gradient (IG) have been proposed as standardised metrics describing physical activity (PA) volume and intensity, respectively. examined hypothesised between-group PA differences in AvAcc and IG, and their associations with health and well-being indicators in children. ActiGraph GT9X wrist accelerometers were worn for 24-h·d over 7days by 145 children aged 9-10. Raw accelerations were averaged per 5-s epoch to represent AvAcc over 24-h. IG represented the relationship between log values for intensity and time. Moderate-to-vigorous PA (MVPA) was estimated using youth cutpoints. BMI z-scores, waist-to-height ratio (WHtR), peak oxygen uptake (VOpeak), Metabolic Syndrome risk (MetS score), and well-being were assessed cross-sectionally, and 8-weeks later. Hypothesised between-group differences were consistently observed for IG only (p < .001). AvAcc was strongly correlated with MVPA ( = 0.96), while moderate correlations were observed between IG and MVPA ( = 0.50) and AvAcc ( = 0.54). IG was significantly associated with health indicators, independent of AvAcc ( < .001). AvAcc was associated with well-being, independent of IG ( < .05). IG was significantly associated with WHtR ( < .01) and MetS score ( < .05) at 8-weeks follow-up. IG is sensitive as a gauge of PA intensity that is independent of total PA volume, and which relates to important health indicators in children.
平均加速度（AvAcc）和强度梯度（IG）已被提议作为分别描述体力活动（PA）量和强度的标准化指标。本研究旨在检验假设的组间 PA 在 AvAcc 和 IG 方面的差异，以及它们与儿童健康和幸福感指标的关系。145 名 9-10 岁的儿童佩戴 ActiGraph GT9X 腕部加速度计进行 7 天 24 小时的测量。原始加速度值以 5 秒的时间间隔平均，以代表 24 小时内的 AvAcc。IG 代表了强度和时间的对数值之间的关系。使用青少年切点估计中等到剧烈体力活动（MVPA）。使用横断面和 8 周后评估 BMI z 分数、腰高比（WHtR）、峰值摄氧量（VOpeak）、代谢综合征风险（MetS 评分）和幸福感。仅观察到 IG 存在组间差异（p<0.001）。AvAcc 与 MVPA 呈强相关（=0.96），而 IG 与 MVPA（=0.50）和 AvAcc（=0.54）之间存在中度相关性。IG 与健康指标显著相关，独立于 AvAcc（<0.001）。AvAcc 与幸福感相关，独立于 IG（<0.05）。IG 与 8 周随访时的 WHtR（<0.01）和 MetS 评分（<0.05）显著相关。IG 是一种敏感的 PA 强度指标，与总 PA 量无关，与儿童的重要健康指标相关。
