^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波谱研究了骨骼肌肌内和肌外脂肪(IMCL)和肌外脂肪(EMCL)浓度随年龄的变化，并研究了它们与体脂百分比、W/H比和血液成分的关系。47名年龄在20-74岁之间、体重指数(BMI)为25 kg/m^2的受试者参与了这项研究。受试者按性别被分成年龄和体重指数匹配的年轻组和老年组。老年组SOL和MG中IMCL和EMCL含量显著高于青年组(P<0.01)。因此，老年人SOL(比目鱼肌)和MG(腓肠肌内侧)的总脂含量也明显高于老年人。而胫前肌IMCL和EMCL含量与年龄无明显差异。在EMCL/IMCL比值方面，TA和MG随年龄增长而不同。各肌肉的肌内脂肪含量(IMCL和EMCL)与BMI之间没有相关性。然而，所有骨骼肌中IMCL和EMCL的含量与腰臀比(WHR)显著相关。此外，在TA和MG中，体脂百分比与IMCL显著相关(p&lt；0.05)。所有骨骼肌中IMCL和EMCL含量与HbA1c、TG、TC、LDL-C浓度显著相关。这些结果表明，与年龄相关的心肌细胞内脂质的增加可能与身体成分、血脂和脂蛋白谱有关，这可能影响瘦削老年人的健康风险和肌肉随年龄的下降。

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.