Physical Activity Type and Intensity Are Associated With Abdominal Muscle Area and Density: The Multiethnic Study of Atherosclerosis.

Background: Using data from a multiethnic cohort, the authors tested associations of multiple types and intensities of physical activity (PA) with abdominal muscle area and density.

Methods: 1895 Multiethnic Study of Atherosclerosis participants (mean age 64.6 [9.6] y) completed health history and PA questionnaires and computed tomography to quantify body composition and measurements of cardiovascular and inflammatory biomarkers. Analyses included multivariable regression.

Results: Compared with those not meeting PA guidelines for Americans, those meeting the guidelines had higher total abdominal muscle area (odds ratio, 95% confidence interval 1.60, 1.20 to 2.15), stability muscle area (1.68, 1.28 to 2.20), and stability muscle density (1.35, 1.03 to 1.76). After adjustment for relevant covariates, each SD increase in total moderate to vigorous PA was associated with a higher total abdominal (β, 95% confidence interval = 0.068, 0.036 to 0.173), stability (0.063, 0.027 to 0.099), and locomotor (0.069, 0.039 to 0.099) muscle area and higher locomotor muscle density (0.065, 0.022 to 0.108, P < .01). Only intentional and conditioning exercise were associated with total abdominal and stability muscle density (P < .05). Light PA and walking were not associated with muscle area or density.

Conclusions: Most types of PA are positively associated with abdominal muscle area and density across functional categories, independent of relevant covariates. These results provide additional evidence for promoting PA for healthy muscle aging.