Author(s): SANDO, E., KITAGAWA, F., KOIKE, T., TANAKA, N., AKIMA, H., Institution: NAGOYA UNIVERSITY, Country: JAPAN, Abstract-ID: 2387

INTRODUCTION:
Accumulation of adipose tissue within skeletal muscles is referred to as intramuscular adipose tissue (IntraMAT). It is known that excessive IntraMAT accumulation may lead to decrease of muscle strength and/or physical function in older individuals (Goodpaster et al, 2006; Tuttle et al, 2012). To understand the accumulation mechanism of IntraMAT, it is important to accurately characterize the distribution patterns of IntraMAT along the length of the skeletal muscle. According to the previous studies, distribution patterns of IntraMAT content were shown to vary along muscle length of the thigh (Hasson et al, 2011). However, reports on the distribution patterns of IntraMAT are limited. Previous studies have examined men and women together (Yoshiko et al, 2017) and much remains unknown about the distribution patterns of IntraMAT in young and older women. Therefore, the purpose of this study was to clarify regional differences in IntraMAT content in the thigh muscles in young and older women.
METHODS:
Twenty-three young (19.9 ± 1.6 years) and 25 older (72.4 ± 3.2 years) women participated in this study. Magnetic resonance imaging was used to calculate the IntraMAT content (%) of the quadriceps femoris (QF), adductor (AD) and hamstrings (HM) muscle groups. Total thigh was calculated as the sum of QF, AD, and HM. IntraMAT content was determined by calculating the cross-sectional area of IntraMAT relative to the sum of the cross-sectional area of skeletal muscle and IntraMAT. Axial images at 30% (proximal), 50% (middle), and 70% (distal) of the thigh length was evaluated. We compared the IntraMAT content in the proximal, middle, and distal regions of the thigh.
RESULTS:
In the young group, no significant differences in IntraMAT content of the QF were observed among any regions. In contrast, in the older group, IntraMAT content at the distal region was significantly higher than that of the middle (P < 0.05). IntraMAT content of the AD was significantly higher at the distal compared with the proximal and middle regions in both young and older groups (P < 0.001). No significant differences were found in any regions of the HM for both groups. IntraMAT content of the total thigh (i.e. sum of QF, AD, and HM) was significantly higher at the distal region than at the proximal and middle regions for both groups (P < 0.05).
CONCLUSION:
In both young and older women groups, IntraMAT content of the AD and total thigh was higher in the distal region than the proximal and middle regions, indicating that IntraMAT is distributed differently along the length of thigh muscles.