Levels of Sex Hormones and Abdominal Muscle Composition in Men from The Multi-Ethnic Study of Atherosclerosis

Abstract

Information on the associations of testosterone levels with abdominal muscle volume and density in men is limited, while the role of estradiol and SHBG on these muscle characteristics are unclear. Therefore, this study aimed to investigate the association between fasting serum sex hormones and CT-derived abdominal muscle area and radiodensity in adult men. Conducted as a cross sectional observational study using data from the Multi-Ethnic Study of Atherosclerosis, our analyses focused on a community-based sample of 907 men aged 45-84 years, with 878 men having complete data. CT scans of the abdomen were interrogated for muscle characteristics, and multivariable linear regressions were used to test the associations. After adjustment for relevant factors, higher levels of both total testosterone and estradiol were associated with higher abdominal muscle area (1.74, 0.1-3.4, and 1.84, 0.4-3.3, respectively). In the final analyses, levels of total testosterone showed a positive association, while an inverse relationship was observed for SHBG with abdominal muscle radiodensity (0.3, 0.0-0.6, and - 0.33, - 0.6 to - 0.1, respectively). Our results indicate a complex association between sex hormones and abdominal muscle characteristics in men. Specifically, total testosterone and estradiol were associated with abdominal muscle area, while only total testosterone was associated with muscle radiodensity and SHBG was inversely associated with muscle radiodensity.Clinical Trial: NCT00005487.

Figure 1

(a) Presents an axial slice from the lumbar region, including abdominal adipose and muscle tissue. Abdominal tissue was categorized by Hounsfield units (HU), with − 190 to − 30 HU assessed as adipose tissue, − 30 to − 0 HU defined as mixed connective tissue, while values 0 to 100 HU were set as lean muscle^,. Abdominal muscle area and adipose tissue area were calculated by summing the number of pixels, while muscle radiodensity was defined by average HU value measured within that muscle’s corresponding fascial plane. The abdominal muscles were further categorized into stabilizing muscle groups (rectus abdominis, oblique muscle groups and paraspinal muscles) and locomotor muscle groups (psoas muscles). Subcutaneous adipose tissue was determined as adipose tissue in the subcutaneous area, whilst visceral adipose tissue was determined as fat tissue in the visceral cavity, excluding intermuscular fat. (b) Presents a sagittal slice from the lumbar region. 6 transverse cross section slices of data were analyzed; slice 0 is located at the L4/L5 vertebral junction and slice 1 is the immediately superior and adjacent to slice 0. Slice 2 is located at the L3/L4 junction with slice 3 superior and adjacent to slice 2. Slice 4 is located at the L2/L3 vertebral junction with slice 5 superior and adjacent to slice 4. CT scans were set at a collimation of 3 mm with a slice thickness of 6 mm.

Figure 2

Flow-chart showing the number of men included in the final analyses.