Rice C L, Cunningham D A, Paterson D H, Lefcoe M S
Faculty of Physical Education, University of Western Ontario, London, Canada.
Clin Physiol. 1989 Jun;9(3):207-20. doi: 10.1111/j.1475-097x.1989.tb00973.x.
Five computed tomography (CT) scans were taken at measured intervals of the legs and arms of young (n = 7) and elderly (n = 13) men. Cross-sectional areas (CSA) of the total limb, muscle plus bone and bone were measured in each scan, and skin plus subcutaneous tissue areas were calculated by subtraction. In addition, in the arm scans the CSA of the extensor and flexor compartments were measured, and in the leg the CSA of the plantar flexor compartment. A value for lean muscle within these compartments was calculated by excluding non-muscle tissue using density measurements based on Hounsfield units. Related volumes for the various components were also calculated using geometric formulae. The results showed that elderly limbs were of a similar overall size as the young, but elderly muscles were smaller (28-36%) with greater amounts of non-muscle tissue located within a muscle, particularly in the plantar flexors (81% more than in the young). Elderly arms had a greater amount of skin plus subcutaneous tissue than the young, but there was no difference in the legs. Muscle volumes were similar to in vitro results reported from cadaver studies and can be predicted from single mid-limb CT scans using regression equations. These results illustrate that, due to the substantially reduced amount of 'pure' muscle tissue in the elderly, comparisons of relative strength with other populations may be misleading unless appropriate measurements of muscle size are considered. Methods to estimate in vivo physiological CSA, which is considered the best means of normalizing strength, have been demonstrated in this study.
对年轻男性（n = 7）和老年男性（n = 13）的腿部和手臂在规定间隔进行了五次计算机断层扫描（CT）。在每次扫描中测量了四肢、肌肉加骨骼以及骨骼的横截面积（CSA），并通过减法计算出皮肤加皮下组织的面积。此外，在手臂扫描中测量了伸肌和屈肌腔室的CSA，在腿部测量了跖屈肌腔室的CSA。通过基于亨氏单位的密度测量排除非肌肉组织，计算出这些腔室内的瘦肌肉值。还使用几何公式计算了各组成部分的相关体积。结果表明，老年四肢的总体大小与年轻人相似，但老年肌肉较小（小28 - 36%），肌肉内的非肌肉组织较多，尤其是在跖屈肌中（比年轻人多81%）。老年手臂的皮肤加皮下组织比年轻人多，但腿部没有差异。肌肉体积与尸体研究报告的体外结果相似，并且可以使用回归方程通过单次肢体中部CT扫描进行预测。这些结果表明，由于老年人中“纯”肌肉组织的量大幅减少，除非考虑肌肉大小的适当测量，否则与其他人群进行相对力量比较可能会产生误导。本研究展示了估计体内生理CSA的方法，生理CSA被认为是使力量标准化的最佳方法。
