Lifestyle and Clinical Correlates of Myosteatosis Among African Caribbean Men and Women

Background/Objectives: Myosteatosis, i.e., adiposity in and around skeletal muscle, is a hallmark of adverse muscle aging, more common among women than men, and associated with several major health outcomes, including cardiometabolic diseases and functional decline. We investigated lifestyle and clinical correlates of skeletal muscle adiposity among an understudied cohort of Afro-Caribbean men and women. Methods: Among 213 men and 530 women aged 50–80 from the Tobago Health Study, several lifestyle and clinical factors were assessed, including accelerometry-derived physical activity and sleep duration, diet, and medications. Lifestyle risk scores were based on smoking, alcohol, physical activity, and body mass index. Calf muscle density was measured using peripheral quantitative computed tomography, with lower values suggesting more muscle adiposity. Results: Women were more likely to abstain from cigarettes and alcohol, but less physically active, with more sugar intake and lower muscle density than men. Using Isotemporal Substitution, cross-sectionally replacing sedentary time with sleep or light-intensity physical activity was significantly associated with higher muscle density. In multivariable models, older age, larger waist circumference, and taking diabetes medications were cross-sectionally associated with lower muscle density, as well as shorter sleep among men and taking anti-hypertensive medications among women. Conclusions: Older Afro-Caribbean women vs. men had healthier substance habits, but lower activity and muscle density, suggesting more muscle adiposity. Modifiable behaviors, particularly sedentary time, sleep duration, and light-intensity physical activity were strongly associated with muscle density. Interventions that replace sedentary time with light-intensity physical activity and sleep may be feasible and sustainable approaches to reduce myosteatosis.