1H-MRS study on gender differences in intramuscular triglycerides in human skeletal muscle and their relation to body fat and endurance capacity

Abstract

Gender differences were measured in the amount of intramyocellular triglyceride (IMCL) and extramyocellular triglyceride (EMCL) in skeletal muscles using 1H-MR spectroscopy and their relation to body fat and peak V̇O2 was studied. Fourteen apparently healthy subjects were separated into groups by gender. Both the male and female group subjects were selected according to similar ages and BMI (male : n=7, BMI=20.5±0.6 kg/m2, age=21.1±0.7 years, female : n=7, BMI=20.6 ±0.5 kg/m2, age=18.7±0.3 years). We found a significant correlation between IMCL and EMCL in the soleus (SOL : p<0.01) and medial gastrocnemius (MG : p<0.01) muscles. IMCL values in SOL were significantly higher than IMCL values in MG and tibialis anterior muscle (TA) in both males and females in the order of SOL>MG>TA (p<0.01). IMCL and EMCL values in MG and SOL among females were significantly higher (p<0.01) than their corresponding values in males. However, a gender difference in IMCL and EMCL values for TA was not found. There was no correlation between IMCL and EMCL values for each muscle and BMI : but IMCL (r=0.63 in SOL) and EMCL (r=0.88 and r=0.73 in SOL, and MG, respectively ; p< 0.01) values correlated significantly with percent FAT. There was no correlation between IMCL values for each muscle and peak V̇O2 ; but the EMCL values of SOL correlated quite negatively with peak V̇O2 (r=-0.63, p<0.05). These results suggest that there are gender differences in intramyocellular and extramyocellular triglyceride contents. Lipids were positively related to percent body fat in SOL and MG ; EMCL values may have a negative effect on endurance capacity.