Diabetes Research Centre, University of Leicester, Leicester General Hospital, Leicester, UNITED KINGDOM.
NIHR Leicester Biomedical Research Centre, Leicester, UNITED KINGDOM.
Med Sci Sports Exerc. 2018 Jun;50(6):1323-1332. doi: 10.1249/MSS.0000000000001561.
Commonly used physical activity metrics tell us little about the intensity distribution across the activity profile. The purpose of this paper is to introduce a metric, the intensity gradient, which can be used in combination with average acceleration (overall activity level) to fully describe the activity profile.
A total of 1669 adolescent girls (sample 1) and 295 adults with type 2 diabetes (sample 2) wore a GENEActiv accelerometer on their nondominant wrist for up to 7 d. Body mass index and percent body fat were assessed in both samples and physical function (grip strength, Short Physical Performance Battery, and sit-to-stand repetitions) in sample 2. Physical activity metrics were as follows: average acceleration (AccelAV); the intensity gradient (IntensityGRAD from the log-log regression line: 25-mg intensity bins [x]/time accumulated in each bin [y]); total moderate-to-vigorous physical activity (MVPA); and bouted MVPA (sample 2 only).
Correlations between AccelAV and IntensityGRAD (r = 0.39-0.51) were similar to correlations between AccelAV and bouted MVPA (r = 0.48) and substantially lower than between AccelAV and total MVPA (r ≥ 0.93). IntensityGRAD was negatively associated with body fatness in sample 1 (P < 0.05) and positively associated with physical function in sample 2 (P < 0.05); associations were independent of AccelAV and potential covariates. By contrast, MVPA was not independently associated with body fatness or physical function.
AccelAV and IntensityGRAD provide a complementary description of a person's activity profile, each explaining unique variance, and independently associated with body fatness and/or physical function. Both metrics are appropriate for reporting as standardized measures and suitable for comparison across studies using raw acceleration accelerometers. Concurrent use will facilitate investigation of the relative importance of intensity and volume of activity for a given outcome.
常用的身体活动指标几乎无法反映活动分布的强度分布。本文的目的是引入一个指标，即强度梯度，该指标可以与平均加速度（整体活动水平）结合使用，以全面描述活动分布。
共有 1669 名青春期女孩（样本 1）和 295 名 2 型糖尿病成年人（样本 2）在非优势手腕上佩戴 GENEActiv 加速度计，最长佩戴 7 天。在两个样本中评估了体重指数和体脂百分比以及身体功能（握力、短体性能电池和坐站重复次数）在样本 2 中。身体活动指标如下：平均加速度（AccelAV）；强度梯度（从对数-对数回归线得出的强度梯度：25-mg 强度箱[x]/时间在每个箱中积累的时间 [y]）；总中度至剧烈体力活动（MVPA）；和爆发性 MVPA（仅样本 2）。
AccelAV 与 IntensityGRAD（r = 0.39-0.51）之间的相关性与 AccelAV 与爆发性 MVPA（r = 0.48）之间的相关性相似，但明显低于 AccelAV 与总 MVPA（r≥0.93）之间的相关性。IntensityGRAD 与样本 1 中的体脂含量呈负相关（P <0.05），与样本 2 中的身体功能呈正相关（P <0.05）；这些关联独立于 AccelAV 和潜在的协变量。相比之下，MVPA 与体脂含量或身体功能无关。
AccelAV 和 IntensityGRAD 提供了对一个人活动分布的补充描述，每个描述都解释了独特的方差，并与体脂含量和/或身体功能独立相关。这两个指标都适合作为标准化指标报告，适合使用原始加速度计进行研究之间的比较。同时使用将有助于研究活动强度和活动量对特定结果的相对重要性。
