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

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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.