The purpose of this study was to estimate intramuscular fat (IMF) in healthy young and elderly people and examine the relationship between estimated IMF index and cross-sectional area (CSA) of the vastus lateralis (VL) and biceps femoris-long head (BFl) muscles. Twenty physically active volunteers, 10 young (5 male, 5 female; age 21 yr) and 10 elderly (5 male, 5 female; age 71 yr) participated in this study. Echo intensity of the VL at the lateral and BFl at the posterior mid-thigh was measured using ultrasonography, which was calculated based on mean grey scale. The CSA of VL and BFl muscles at the mid-thigh was measured using a 3.0 T magnetic resonance imaging (MRI). Echo intensity of elderly group was significantly higher than that of young group (all p<0.001), and CSA of elderly group was smaller than that of young group (VL, p<0.01; BFl, p<0.05). A significant correlation was not found between echo intensity and CSA [CSA・L⁻² (×10⁻⁴ )] in each group. These results deny the relationship between IMF contents and muscle mass both in young and elderly individuals.

DESCENTE SPORTS SCIENCE Vol.34/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE