Factors related to trunk intramuscular adipose tissue content - A comparison of younger and older men

The present study investigated factors related to trunk intramuscular adipose tissue (IntraMAT) content in younger and older men. Twenty-three healthy younger (20 to 29 years) and 20 healthy older men (63 to 79 years) participated in this study. The trunk IntraMAT content was measured using magnetic resonance imaging at the height of the 3rd lumbar vertebra. In addition to blood properties and physical performance, dietary intake was assessed by a self-administered diet history questionnaire. The dietary intake status was quantified using the nutrient adequacy score for the intake of 10 selected nutrients by summing the number of items that met the criteria of dietary reference intakes for Japanese individuals. The results obtained revealed that the trunk IntraMAT content was significantly higher in the older group than in the younger group (p < 0.05). In the younger group, the trunk IntraMAT content significantly correlated with systolic and diastolic blood pressure and HbA1c (r_s = 0.443 to 0.464, p < 0.05). In the older group, significant and negative correlations were observed between the trunk IntraMAT content and 5-m usual walking speed, handgrip strength, and nutrient adequacy scores (r_s = -0.485 to -0.713, p < 0.05). These results indicate that factors associated with the trunk IntraMAT content differed in an age dependent manner. In the younger group, the trunk IntraMAT content correlated with the metabolic status such as blood pressure and HbA1c. In the older group, physical performance and the dietary intake status negatively correlated with the trunk IntraMAT content.