Riyahi-Alam Sadjad, Mansournia Mohammad Ali, Kabirizadeh Yaser, Mansournia Nasrin, Steyerberg Ewout, Kordi Ramin
Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
Sports Medicine Research Center, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Sports Health. 2017 Nov/Dec;9(6):564-569. doi: 10.1177/1941738117705837. Epub 2017 May 9.
Adverse effects of excessive body mass reduction among wrestlers dictate minimum weight determination through body composition. Although skinfold equations are essential to estimate body composition in the field setting, they are mostly derived from Western societies and may lack generalizability to other populations.
Previously published skinfold equations lacked external validity in predicting body density of Iranian wrestlers. We aimed to derive a new anthropometric model specific to young Iranian male wrestlers.
Cross-sectional cohort study.
Level 3.
One hundred twenty-six Iranian male wrestlers with at least 1 year of experience and a mean age of 19 ± 4.0 years underwent underwater weight analysis for body density estimation and anthropometric measurements. The previously published equations were validated, followed by new regression modeling, using multivariable fractional polynomials, with body density as the criterion predicted by common anthropometric variables. The final model was validated throughout the modeling procedure using 1000 bootstrap replications.
The mean body fat percentage (%BF) was 12.6% (95% CI, 11.9%-13.4%), lower than that of previous studies. Six previously published equations each had significant deviations from the line of identity (all P < 0.001). The new prediction equation combined subscapular, tricipital, and midaxillary skinfolds and body mass index cubed to predict body density.
The development of ethnicity-specific equations, using statistically unbiased and comprehensive validation methods, is imperative for body composition estimation to determine the minimum weight for regulation of health in athletes.
Using equations without external validation can bias the prediction of minimum weight, leading to unsafe weight reduction by athletes. Compared with a previous study, much lower mean %BF was found using an ethnicity-specific equation (12.6% vs 15.9%). This difference observed in %BF prediction could affect safe fat reduction in athletes.
摔跤运动员过度减重的不良影响决定了通过身体成分来确定最低体重。虽然皮褶厚度公式对于在现场环境中估计身体成分至关重要，但它们大多源自西方社会，可能不适用于其他人群。
先前发表的皮褶厚度公式在预测伊朗摔跤运动员身体密度方面缺乏外部有效性。我们旨在推导一个针对伊朗年轻男性摔跤运动员的新人体测量模型。
横断面队列研究。
3级。
126名有至少1年经验且平均年龄为19±4.0岁的伊朗男性摔跤运动员接受了水下称重分析以估计身体密度，并进行了人体测量。对先前发表的公式进行验证，随后使用多变量分数多项式进行新的回归建模，以身体密度作为由常见人体测量变量预测的标准。在整个建模过程中使用1000次自助重复抽样对最终模型进行验证。
平均体脂百分比（%BF）为12.6%（95%CI，11.9%-13.4%），低于先前研究。先前发表的六个公式均与恒等线有显著偏差（所有P<0.001）。新的预测公式结合了肩胛下、肱三头肌和腋中皮褶厚度以及立方体质指数来预测身体密度。
使用无统计学偏差且全面的验证方法开发特定种族的公式对于估计身体成分以确定运动员健康调节的最低体重至关重要。
使用未经外部验证的公式可能会使最低体重预测产生偏差，导致运动员进行不安全的减重。与先前的一项研究相比，使用特定种族的公式发现平均%BF要低得多（12.6%对15.9%）。在%BF预测中观察到的这种差异可能会影响运动员安全减脂。
