Huang Yi-Ching, Malina Robert M
Department of Exercise and Health Science, National Taipei College of Nursing, Taipei, Taiwan.
Med Sci Sports Exerc. 2007 Apr;39(4):701-8. doi: 10.1249/mss.0b013e31802f0512.
The purpose of the study was to evaluate the cross-sectional relationship between BMI and a physical fitness index (PFI) based on four indicators of fitness in a national sample of Taiwanese youth.
Height, weight, and four measures of physical fitness (sit-ups completed in 60 s, standing long jump, sit and reach, and 800- or 1600-m run/walk) were measured in a national sample of 102,765 Taiwanese youth 9-18 yr of age: 50,940 girls and 51,825 boys. BMI was calculated for each subject. Within each sex-specific half-year age group, students were classified into five BMI categories based on national percentiles: very low, BMI < 5th percentile; low, BMI >or= 5th but < 15th percentiles; normal, BMI >or= 15th but < 85th percentiles; high, BMI >or= 85th but < 95th percentiles; and very high, BMI >or= 95th percentiles. Z-scores based on sex- and age-specific means and standard deviations were calculated, and the sum of z-scores for the four fitness tests was used as a PFI. Differences in PFI between BMI categories within each sex-specific half-year age group were compared with ANOVA with Bonferroni adjustments. Sex-specific regressions of PFI on BMI, using a nonlinear quadratic model, were done in four broader age categories.
Relationships between BMI and PFI are nonlinear and vary with age from late childhood through adolescence. With increasing age during adolescence, the relationship becomes parabolic, and the peaks of the parabola are sharper in adolescent boys than girls.
PFI declines in a curvilinear manner with increasing BMI among youth 9-18 yr of age, but the slope of the relationship varies with age.
本研究旨在评估台湾青少年全国样本中，基于四项体能指标的身体质量指数（BMI）与体能指数（PFI）之间的横断面关系。
对102,765名9至18岁台湾青少年全国样本进行身高、体重及四项体能测试（60秒仰卧起坐、立定跳远、坐位体前屈以及800米或1600米跑/走）测量，其中女孩50,940名，男孩51,825名。计算每个受试者的BMI。在每个特定性别的半年年龄组内，根据全国百分位数将学生分为五个BMI类别：极低，BMI<第5百分位数；低，BMI≥第5百分位数但<第15百分位数；正常，BMI≥第15百分位数但<第85百分位数；高，BMI≥第85百分位数但<第95百分位数；以及极高，BMI≥第95百分位数。计算基于性别和年龄特异性均值及标准差的Z分数，并将四项体能测试的Z分数总和用作PFI。在每个特定性别的半年年龄组内，通过方差分析（ANOVA）及Bonferroni校正比较BMI类别之间的PFI差异。在四个更宽泛的年龄类别中，使用非线性二次模型对PFI与BMI进行性别特异性回归分析。
BMI与PFI之间的关系是非线性的，且从儿童晚期到青春期随年龄变化。在青春期，随着年龄增长，关系呈抛物线状，且青春期男孩抛物线的峰值比女孩更尖锐。
在9至18岁青少年中，PFI随着BMI的增加呈曲线下降，但这种关系的斜率随年龄变化。
