初中生中高强度体力活动时间及复杂度与体质健康的相关性

调查初中生上学日及周末进行中高强度体力活动(moderate to vigorous physical activity,MVPA)时间及频繁程度的变异性,探究学生MVPA与体质间的相关性.方法 采用整群抽样方法,调查北京市回龙观中学初一及初二学生共79名.使用改编的一日体力活动记录工具调查学生1周8:00-23:00的体力活动情况,依据能量代谢当量(MET值)将每日体力活动分为MVPA及非MVPA部分,制作上学日连续5d及周末连续2d的体力活动时间序列,并计算MVPA总时间及序列的lempel-ziv复杂度.探究MVPA情况与学生体质测试结果的相关性.结果 上学日中,男生与女生的MVPA总时间差异无统计学意义(t=-0.90,P>0.05),女生MVPA时间较男生有更大的变异性(58.9%,53.5%);性别间MVPA复杂度差异无统计学意义(t=-0.55,P>0.05).2天休息日中,性别间MVPA总时间差异无统计学意义(t=-0.13,P>0.05),男生MVPA时间的变异系数(CV)低于女生(]41.5%,152.8%),复杂度差异无统计学意义(t=-0.63,P>0.05),男生MVPA复杂度CV略高于女生(55.1%,48.1%).青少年在上学日的MVPA时间CV,男生上学日及周末(53.5%,141.5%)较女生略低(58.9%,152.8%).男生上学日MVPA复杂度与体质量指数(BMI)中等程度相关(r=0.41),女生MVPA时间与体重和BMI有低程度相关(r值分别为-0.30,-0.31),复杂度均与体重和BMI有低程度相关(r值分别为-0.31,-0.33)(P值均<0.05).结论 初中生在上学日较周末MVPA更活跃,但进行MVPA活动的时间段相对单一.学校可以通过分散一天内MVPA的活动时段达到高效促进体质的效果.MVPA复杂度作为综合性较强的指标,可能与初中生BMI的关联更敏感.

Association between lempel-ziv complexity of moderate to vigorous intensity physical activity time series and physical fitness among adolescents

Objective To investigate the variability of the time and frequency of Moderate to Vigorous Physical Activity( MVPA) during the school days and weekends of junior high school students, and to explore the correlation between MVPA and physical fitness. Methods A cluster sampling method was used to investigate 79 students of grade 1 and grade 2 in Beijing Huilongguan Middle School. Adapted one-day physical activity recording tool was implemented to investigate students’physical activity from 8: 00 to 23: 00 a week, activity records were classified into daily MVPA parts and non-MVPA parts based on MET values. Physical activity time series for 5 consecutive days and 2 weekends, as well as MVPA total time and the lempel-ziv complexity of the sequence was calculated. Investigated the correlation between the MVPA situation and the results of national students’physical fitness standard test. Results There was no statistical difference in MVPA time between males and females during school days( t =-0.90, P>0.05). Females had greater variability in MVPA than males( 58.9%, 53.5%). There was also no statistical difference in MVPA complexity between genders( t =-0.55, P>0.05). During weekends, there was no significant difference in the total MVPA time between men and women( t =-0.13, P>0.05). The CV of male MVPA time was lower than that of female( 141.5%, 152.8%).There was also no significant difference( t =-0.63, P>0.05), and male MVPA complex CV was slightly higher than that of female( 55.1%, 48. 1%). The MVPA time CV of adolescents during weekdays was slightly lower for males( weekdays vs weekends:53.5%, 141.5%) than females( 58.9%, 152.8%). The MVPA complexity in weekdays among males was moderately correlated with BMI( r = 0.41), and the MVPA time and weight of females( r =-0.30) and BMI( r =-0.31) were low. The complexity was related to body weight( r =-0.31) and BMI( r =-0.33) to a low degree( P<0.05). Conclusion Junior middle school students are more active on school days than weekend, but the MVPA time series are limited. Schools can effectively improve physical fitness by spreading out the activity period of MVPA in one day. MVPA complexity, as a more comprehensive indicator, may be more sensitive to BMI of junior middle school students.