Heymsfield S B, Olafson R P, Kutner M H, Nixon D W
Am J Clin Nutr. 1979 Mar;32(3):693-702. doi: 10.1093/ajcn/32.3.693.
Estimation of midarm adipose tissue and muscle by the anthropometric technique is based on the idealized assumption that the arm and its muscle compartments are circular, and that fat is distributed evenly around the arm. We examined the validity of these assumptions by computerized axial tomography of the midarm in 21 subjects ranging from 65 to 255% of ideal body weight. Computerized axial tomography identified three errors inherent in the anthropometric method: 1) The arm and its muscle compartment were rarely circular, but resembled instead an ellipse and "cloverleaf", respectively; 2) fat was distributed asymmetrically around the arm, and furthermore when triceps skinfold was less than 5 mm, no fat was radiographically detectable, and 3) muscle are calculated by the anthropometric method includes bone area. Since bone area was not influenced by nutritional status, anthropometric "muscle area" underestimated the degree of muscle atrophy in undernutrition. Despite these limitations, in subjects 60 to 120% of ideal body weight anthropometric estimates of midarm muscle area (MAMA) and fat area did not differ greatly from the radiographic values. Anthropometric MAMA was consistently greater than the radiographic value by 15 to 25%, while midarm fat area agreed within +/- 10%. The error in the anthropometric MAMA could be nearly eliminated by two types of correction: expressing MAMA as a percentage of normal, and correcting for bone content by subtracting midarm bone area (6.3 and 4.7 cm2 for men and women). In subjects greater than 150% ideal body weight, however, anthropometric estimates of MAMA and midarm fat area differed from the radiographic values by greater than 50% even after the above two types of correction. Midarm computerized axial tomography scan provides an accurate alternative to the anthropometric method for estimating midarm muscle and fat in these obese individuals.
通过人体测量技术估算上臂脂肪组织和肌肉，是基于理想化的假设，即手臂及其肌肉腔室是圆形的，且脂肪均匀分布于手臂周围。我们通过计算机断层扫描，对21名体重为理想体重65%至255%的受试者的上臂进行检查，以验证这些假设的有效性。计算机断层扫描发现人体测量方法存在三个固有误差：1）手臂及其肌肉腔室很少呈圆形，分别更像椭圆形和“三叶草”形；2）脂肪在手臂周围分布不对称，而且当三头肌皮褶厚度小于5毫米时，影像学上无法检测到脂肪；3）通过人体测量方法计算的肌肉面积包括骨面积。由于骨面积不受营养状况影响，人体测量的“肌肉面积”低估了营养不良时肌肉萎缩的程度。尽管存在这些局限性，但对于体重为理想体重60%至120%的受试者，上臂肌肉面积（MAMA）和脂肪面积的人体测量估计值与影像学值差异不大。人体测量的MAMA始终比影像学值大15%至25%，而上臂脂肪面积的差异在±10%以内。人体测量MAMA的误差可通过两种校正方法几乎消除：将MAMA表示为正常值的百分比，并通过减去上臂骨面积（男性和女性分别为6.3平方厘米和4.7平方厘米）校正骨含量。然而，对于体重超过理想体重150%的受试者，即使经过上述两种校正，MAMA和上臂脂肪面积的人体测量估计值与影像学值的差异仍大于50%。上臂计算机断层扫描为这些肥胖个体估算上臂肌肉和脂肪提供了一种替代人体测量方法的准确手段。
