Maden-Wilkinson T M, McPhee J S, Rittweger J, Jones D A, Degens H
Institute for Research into Human Movement and Health, School of Healthcare Science, Manchester Metropolitan University, John Dalton Building, Oxford Road, Manchester, M1 5GD, UK.
Age (Dordr). 2014 Feb;36(1):383-93. doi: 10.1007/s11357-013-9571-6. Epub 2013 Aug 11.
Secular changes and intra-individual differences in body shape and size can confound cross-sectional studies of muscle ageing. Normalising muscle mass to height squared is often suggested as a solution for this. We hypothesised that normalisation of muscle volume to femur volume may be a better way of determining the extent of muscle lost with ageing (sarcopenia). Thigh and femur muscle volumes were measured from serial magnetic resonance imaging sections in 20 recreationally active young men (mean age 22.4 years), 25 older men (72.3 years), 18 young women (22.1 years) and 28 older women (72.0 years). There were no age-related differences in femur volume. The relationship between thigh muscle volume and femur volume (R (2) = 0.76; exponent of 1.12; P < 0.01) was stronger than that with height (R (2) = 0.49; exponent of 3.86; P < 0.01) in young participants. For young subjects, the mean muscle/bone ratios were 16.0 and 14.6 for men and women, respectively. For older men and women, the mean ratios were 11.6 and 11.5, respectively. The Z score for the thigh muscle/bone volume ratio relative to young subjects was -2.2 ± 0.7 for older men and -1.4 ± 0.8 for older women. The extent of sarcopenia judged by the muscle/bone ratio was approximately twice that determined when normalising to height squared. These data suggest that the muscle/bone ratio captures the intra-individual loss of muscle mass during ageing, and that the age-related loss of muscle mass may be underestimated when normalised to height squared. The quadriceps seems relatively more affected by ageing than other thigh muscles.
身体形状和大小的长期变化以及个体差异可能会混淆肌肉衰老的横断面研究。人们通常建议将肌肉质量除以身高的平方进行标准化，以此作为解决方案。我们假设将肌肉体积与股骨体积进行标准化，可能是确定衰老过程中肌肉流失程度（肌肉减少症）的更好方法。通过连续磁共振成像切片测量了20名年轻男性（平均年龄22.4岁）、25名老年男性（72.3岁）、18名年轻女性（22.1岁）和28名老年女性（72.0岁）的大腿和股骨肌肉体积。股骨体积不存在与年龄相关的差异。在年轻参与者中，大腿肌肉体积与股骨体积之间的关系（R² = 0.76；指数为1.12；P < 0.01）比与身高的关系（R² = 0.49；指数为3.86；P < 0.01）更强。对于年轻受试者，男性和女性的平均肌肉/骨骼比率分别为16.0和14.6。对于老年男性和女性，平均比率分别为11.6和11.5。相对于年轻受试者，老年男性大腿肌肉/骨骼体积比的Z评分为-2.2 ± 0.7，老年女性为-1.4 ± 0.8。通过肌肉/骨骼比率判断的肌肉减少症程度约为除以身高平方进行标准化时确定程度的两倍。这些数据表明，肌肉/骨骼比率反映了衰老过程中个体肌肉质量的损失，并且当除以身高平方进行标准化时，与年龄相关的肌肉质量损失可能被低估。股四头肌似乎比其他大腿肌肉更容易受到衰老的影响。
