Del Pozo-Cruz Borja, Gant Nicholas, Del Pozo-Cruz Jesús, Maddison Ralph
Department of Exercise Sciences, Faculty of Science, University of Auckland (Auckland, New Zealand). TAMAKI BUILDING 731 -, Level 3, Tamaki Campus Gate 1,St Johns, Auckland, New Zealand.
Department of Physical Education and Sports, University of Seville (Seville, Spain), Pirotecnia s/n, Seville, Spain.
PLoS One. 2017 Sep 12;12(9):e0184472. doi: 10.1371/journal.pone.0184472. eCollection 2017.
The evidence regarding the unique effect of sedentary behaviour on obesity among children is unclear. Moreover, the effect of substituting sedentary behaviour with physical activity of different intensities on the body composition of children has received limited empirical study.
To examine the mathematical effects on Body Mass Index (BMI) of substituting sedentary behaviours with physical activities of different intensities on children and youth aged 5-14 years old in New Zealand.
Secondary analysis of accelerometer data from the National Survey of Children and Young People's Physical Activity and Dietary Behaviours in New Zealand (2008/09) was conducted. A total of 1812 children and youth aged 5-24 years provided accelerometer-derived data on daily sedentary time (SB), light intensity physical activity (LPA) and moderate to vigorous physical activity (MVPA). Sleep time was assessed with a validated computerised use-of-time tool. BMI was assessed using anthropometric measurements. Multiple linear regression models were used to examine the independent associations of SB, Sleep time, LPA, and MVPA on BMI. The isotemporal substitution approach was used to ascertain the mathematical effect of substituting each of the other behaviours on BMI. Analyses were stratified by age groups.
SB showed a unique (inverse) association with BMI across all age groups (p<0.05) but 20-24 years (p>0.05). Similarly, MVPA was positively associated (p<0.001) across all age groups. Among age groups 5-9 years, 10-14 years and 15-19 years, the estimated impact of replacing 60 min/day of SB with the same amount of MVPA time resulted in decreased BMI for all age groups (p<0.001), ranging from -1.26 (5-9 years) to -1.43 units (15-19 years). Similar results were achieved when SB was replaced with LPA or sleeping time for children (5-19 years). In young people (age group 20-24), the impact of replacing 30 min/day of SB with MVPA resulted in an estimated -1 BMI units decrease (p<0.001).
MVPA and SB have a unique effect on BMI. Further, substituting SB with LPA or MVPA was associated with a favourable effect on BMI across all age groups; with MVPA having the strongest association.
关于久坐行为对儿童肥胖的独特影响，现有证据尚不明确。此外，用不同强度的体育活动替代久坐行为对儿童身体成分的影响，相关实证研究有限。
研究在新西兰，用不同强度的体育活动替代5至14岁儿童和青少年的久坐行为，对其体重指数（BMI）产生的数学影响。
对新西兰儿童和青少年身体活动与饮食行为全国调查（2008/09）中的加速度计数据进行二次分析。共有1812名5至24岁的儿童和青少年提供了基于加速度计得出的每日久坐时间（SB）、轻度身体活动（LPA）和中度至剧烈身体活动（MVPA）的数据。使用经过验证的计算机化时间使用工具评估睡眠时间。通过人体测量评估BMI。采用多元线性回归模型研究SB、睡眠时间、LPA和MVPA与BMI之间的独立关联。采用等时替代法确定用其他行为替代每种行为对BMI的数学影响。分析按年龄组分层。
在所有年龄组中，SB与BMI呈独特的（负）关联（p<0.05），但20至24岁年龄组除外（p>0.05）。同样，MVPA在所有年龄组中均呈正相关（p<0.001）。在5至9岁、10至14岁和15至19岁年龄组中，用相同时长的MVPA替代每天60分钟的SB，估计对所有年龄组的BMI都有降低作用（p<0.001），降低幅度从-1.26（5至9岁）到-1.43单位（15至19岁）。当用LPA或睡眠时间替代儿童（5至19岁）的SB时，也得到了类似结果。在年轻人（20至24岁年龄组）中，用MVPA替代每天30分钟的SB，估计BMI降低1个单位（p<0.001）。
MVPA和SB对BMI有独特影响。此外，用LPA或MVPA替代SB对所有年龄组的BMI都有有利影响；其中MVPA的关联最强。
