^1H-MRS study on age differences in intramuscular lipids in human skeletal muscle and their relation to body composition and blood component

在这项研究中，我们使用^1H-MR光谱观察了骨骼肌中细胞内脂质（IMCL）和细胞外脂质（EMCL）浓度随年龄的变化，并研究了它们与体脂%、W/H比和血液成分的关系。47名年龄在20-74岁之间、身体质量指数(BMI) <25kg/m^2的受试者参加了研究。受试者按性别分为年龄和bmi匹配的年轻组和老年组。老年人SOL和MG中IMCL和EMCL含量高于年轻人（p<0.01）。因此，老年人比目鱼肌（SOL）和腓肠肌内侧肌（MG）的总脂质也明显升高。然而，胫前肌的IMCL或EMCL含量与年龄没有差异。在EMCL/IMCL比值方面，TA和MG随年龄的增长有差异。每块肌肉的肌内脂质含量（包括IMCL和EMCL）与BMI之间没有相关性。然而，在所有骨骼肌中，IMCL和EMCL含量与腰臀比（WHR）显著相关。此外，体脂百分比与TA和MG的IMCL之间存在显著相关性（p<0.05）。各骨骼肌IMCL和EMCL含量与HbA1c、TG、TC、LDL-C浓度显著相关。这些结果表明，与年龄相关的细胞内脂质增加可能与身体成分、血脂和脂蛋白谱有关，这可能会影响瘦弱老年人的健康风险和肌肉随年龄的衰减。

In this study we looked at changes with age in intramyocellular lipid (IMCL) and extramyocellular lipid (EMCL) concentrations in skeletal muscles using ^1H-MR spectroscopy and studied their relation to % body fat, W/H ratio, and blood components. Forty-seven subjects with an age range of 20-74 yrs and a body mass index (BMI) of <25kg/m^2 took part in the study. Subjects were grouped by gender into age- and BMI-matched young and old groups. IMCL and EMCL content in SOL and MG in the old was found to be higher (p<0.01) than that in young. Therefore, total lipids in SOL (soleus muscle) and MG (medial gastrocnemius muscle) were also markedly higher in the old. However, no difference was found in IMCL or EMCL content with age in TA (tibialis anterior muscle). In terms of EMCL/IMCL ratio, a difference was found in TA and MG with age. No correlation was found between intramuscular lipid content (both for IMCL and EMCL) in each muscle and BMI. However, IMCL and EMCL contents correlated significantly with waist-hip ratio (WHR) in all skeletal muscles. Moreover, a significant relationship was observed between % body fat and IMCL in TA and MG (p<0.05). IMCL and EMCL content in all skeletal muscle significantly correlated to HbA1c,TG,TC,LDL-C concentrations. These results suggest that an age-related increase in intramyocellular lipid on might be related to body composition, blood lipids and lipoprotein profiles, and that this might affect health risks and muscle attenuation with age in lean elderly persons.