Relationship between rectus abdominis muscle thickness and metabolic syndrome in middle-aged men

Background and objective Skeletal muscle has been suggested as an important factor in the pathophysiology of metabolic syndrome. During the aging process, muscle mass is lost in specific body parts. However, few studies have investigated the relationship between site-specific muscle loss assessed using computed tomography (CT) and metabolic syndrome. This study was conducted to investigate the association between metabolic syndrome and rectus abdominis muscle thickness at the umbilicus level (RAM), which reflects site-specific muscle loss of the abdomen using CT image. Methods This cross-sectional study was conducted on 725 middle-aged Korean men. Anthropometric evaluation and biochemical tests were performed. The RAMs of the subjects were measured from CT images taken at the umbilicus level. Results The mean RAM (mean +/- SD) of subjects with metabolic syndrome was 2.46 +/- 0.01, which was thinner than that of subjects without metabolic syndrome (2.52 +/- 0.01, p<0.01). Moreover, RAM decreased as the number of metabolic syndrome components increased (p-value for trend<0.01). RAM was positively correlated with body mass index (r = 0.21, p<0.01), skeletal muscle index (r = 0.26, p<0.01), and creatinine (r = 0.12, p<0.01), while RAM was negatively correlated with age(r = -0.11, p<0.01), abdominal circumference(r = -0.22, p<0.01), fasting glucose (r = -0.10, p<0.01), and triglycerides(r = -0.15, p<0.01). Using a stepwise multiple logistic regression analysis, we found that RAM was an independent factor associated with metabolic syndrome (OR: 0.861, 95% CI, 0.779-0.951, p<0.01). The result was not different in the statistical analysis including the components of MS (OR: 0.860, 95% CI, 0.767-0.965, p = 0.01). Conclusion RAM was associated with metabolic syndrome in middle-aged men. Moreover, site-specific muscle loss at the abdomen, as evaluated by RAM, also may be a predictor of metabolic syndrome like SMI.