Research Unit for Exercise Epidemiology, Department of Sports Science and Clinical Biomechanics, Centre of Research in Childhood Health, University of Southern Denmark, Odense, Denmark.
Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK.
Int J Obes (Lond). 2018 Sep;42(9):1639-1650. doi: 10.1038/s41366-018-0152-8. Epub 2018 Jul 13.
To determine the role of physical activity intensity and bout-duration in modulating associations between physical activity and cardiometabolic risk markers.
A cross-sectional study using the International Children's Accelerometry Database (ICAD) including 38,306 observations (in 29,734 individuals aged 4-18 years). Accelerometry data was summarized as time accumulated in 16 combinations of intensity thresholds (≥500 to ≥3000 counts/min) and bout-durations (≥1 to ≥10 min). Outcomes were body mass index (BMI, kg/m), waist circumference, biochemical markers, blood pressure, and a composite score of these metabolic markers. A second composite score excluded the adiposity component. Linear mixed models were applied to elucidate the associations and expressed per 10 min difference in daily activity above the intensity/bout-duration combination. Estimates (and variance) from each of the 16 combinations of intensity and bout-duration examined in the linear mixed models were analyzed in meta-regression to investigate trends in the association.
Each 10 min positive difference in physical activity was significantly and inversely associated with the risk factors irrespective of the combination of intensity and bout-duration. In meta-regression, each 1000 counts/min increase in intensity threshold was associated with a -0.027 (95% CI: -0.039 to -0.014) standard deviations lower composite risk score, and a -0.064 (95% CI: -0.09 to -0.038) kg/m lower BMI. Conversely, meta-regression suggested bout-duration was not significantly associated with effect-sizes (per 1 min increase in bout-duration: -0.002 (95% CI: -0.005 to 0.0005) standard deviations for the composite risk score, and -0.005 (95% CI: -0.012 to 0.002) kg/m for BMI).
Time spent at higher intensity physical activity was the main determinant of variation in cardiometabolic risk factors, not bout-duration. Greater magnitude of associations was consistently observed with higher intensities. These results suggest that, in children and adolescents, physical activity, preferably at higher intensities, of any bout-duration should be promoted.
确定身体活动强度和持续时间在调节身体活动与心血管代谢风险标志物之间关联中的作用。
一项横断面研究使用了国际儿童加速度计数据库（ICAD），其中包括 38306 个观察结果（在 4-18 岁的 29734 个人中）。将加速度计数据总结为在 16 种强度阈值（≥500 至≥3000 计数/分钟）和持续时间（≥1 至≥10 分钟）组合中积累的时间。结果是体重指数（BMI，kg/m）、腰围、生化标志物、血压和这些代谢标志物的综合评分。应用线性混合模型阐明关联，并表达每天高于强度/持续时间组合 10 分钟的活动差异。从线性混合模型中检查的强度和持续时间的 16 种组合中的每一种组合的估计值（和方差）都在荟萃回归中进行了分析，以研究关联中的趋势。
无论强度和持续时间组合如何，身体活动每增加 10 分钟，风险因素都呈显著负相关。在荟萃回归中，强度阈值每增加 1000 计数/分钟，复合风险评分降低 0.027（95%CI：-0.039 至-0.014）标准差，BMI 降低 0.064（95%CI：-0.09 至-0.038）kg/m。相反，荟萃回归表明，持续时间与效应大小没有显著相关（每增加 1 分钟持续时间：复合风险评分增加 0.002（95%CI：-0.005 至 0.0005）标准差，BMI 增加 0.005（95%CI：-0.012 至 0.002）kg/m）。
高强度体育活动的时间是心血管代谢风险因素变化的主要决定因素，而不是持续时间。随着强度的增加，观察到的关联幅度更大。这些结果表明，在儿童和青少年中，应提倡任何持续时间的高强度体育活动，最好是高强度的。
