Jenkins Gabrielle P, Evenson Kelly R, Herring Amy H, Hales Derek, Stevens June
1Department of Epidemiology, Gillings School of Global Public Health at the University of North Carolina at Chapel Hill, Chapel Hill, NC; 2Department of Biostatistics, Gillings School of Global Public Health at the University of North Carolina at Chapel Hill, Chapel Hill, NC; 3Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC; and 4Department of Nutrition, Gillings School of Global Public Health at the University of North Carolina at Chapel Hill, Chapel Hill, NC.
Med Sci Sports Exerc. 2017 Sep;49(9):1826-1833. doi: 10.1249/MSS.0000000000001310.
Daily or weekly averages of physical activity and sedentary behavior could mask patterns of behavior throughout the week that independently affect cardiovascular health. We examined associations between day-to-day physical activity and sedentary behavior latent classes and cardiovascular disease (CVD) risk factors in U.S. youth.
Data were from 3984 youth ages 6-17 yr from the National Health and Nutrition Examination Survey (2003-2006) and from previously published accelerometry latent classes characterizing average counts per minute and percent of wear time in moderate-to-vigorous physical activity (MVPA) and sedentary behavior. Multiple linear regression was used to examine associations of the classes with waist circumference, systolic and diastolic blood pressure, HDL-C and LDL-C, triglycerides, glucose, and insulin.
Participants spent 50.4% of the day in sedentary behavior and 5.3% of the day in moderate-to-vigorous physical activity. Average counts per minute were 516.4 for a 7-d period. Significant differences in CVD risk factors were between extreme classes with few differences observed in intermediate classes. Youth in latent class 4 (highest average counts per minute) had lower systolic blood pressure (-4.11 mm Hg, 95% confidence interval [CI] = -7.74 to -0.55), lower glucose (-4.25 mg·dL, 95% CI = -7.84 to -0.66]), and lower insulin (-6.83 μU·mL, 95% CI = -8.66 to -4.99]) compared with youth in class 1 (lowest average counts per minute). Waist circumference was lower for the least sedentary class (-2.54 cm, 95% CI = -4.90 to -0.19) compared with the most sedentary class. Some associations were attenuated when classes were adjusted for mean physical activity or sedentary level.
There is some indication that patterns, in addition to the total amount of physical activity and sedentary behavior, may be important for cardiovascular health in youth. Longitudinal studies are needed to examine associations between physical activity and sedentary behavior patterns and changes in CVD risk factors.
身体活动和久坐行为的每日或每周平均值可能会掩盖一周内对心血管健康有独立影响的行为模式。我们研究了美国青少年日常身体活动和久坐行为潜在类别与心血管疾病（CVD）危险因素之间的关联。
数据来自国家健康与营养检查调查（2003 - 2006年）中3984名6 - 17岁的青少年，以及先前发表的加速度计潜在类别数据，这些数据表征了每分钟的平均计数以及中度至剧烈身体活动（MVPA）和久坐行为中的佩戴时间百分比。使用多元线性回归来研究这些类别与腰围、收缩压和舒张压、高密度脂蛋白胆固醇（HDL - C）和低密度脂蛋白胆固醇（LDL - C）、甘油三酯、葡萄糖和胰岛素之间的关联。
参与者一天中有50.4%的时间处于久坐行为，5.3%的时间处于中度至剧烈身体活动。7天期间每分钟的平均计数为516.4次。CVD危险因素在极端类别之间存在显著差异，而在中间类别中观察到的差异较小。与第1类（每分钟平均计数最低）的青少年相比，第4类（每分钟平均计数最高）的青少年收缩压较低（-4.11毫米汞柱，95%置信区间[CI] = -7.74至-0.55）、葡萄糖较低（-4.25毫克·分升，95% CI = -7.84至-0.66）以及胰岛素较低（-6.83微单位·毫升，95% CI = -8.66至-4.99）。与久坐时间最长的类别相比，久坐时间最少的类别腰围较低（-2.54厘米，95% CI = -4.90至-0.19）。当对类别进行平均身体活动或久坐水平调整时，一些关联减弱。
有迹象表明，除了身体活动和久坐行为的总量外，行为模式可能对青少年的心血管健康很重要。需要进行纵向研究来检查身体活动和久坐行为模式与CVD危险因素变化之间的关联。
