Introduction:
Skeletal muscle is the largest organ in the human body and vital to maintaining metabolic homeostasis. Increased skeletal muscle fat infiltration (i.e. myosteatosis) is now recognized as a major risk factor for cardio-metabolic diseases, independent of general obesity. Modifications in lifestyle, such as sleep, to reduce myosteatosis would be of great public health importance. However, studies of this relationship often use subjective data and are lacking in minority populations. The aim of this study was to examine the relation between objectively measured sleep duration and myosteatosis at the calf among African Caribbeans.
Methods:
Data were collected on men (n=393) and women (n=438) from the Tobago Health Study. Sleep duration and physical activity was collected using a SenseWear Pro Armband (BodyMedia, Inc.). Participants were instructed to wear the armband at all times, except in water, for 4-7 days. Measures of muscle density, intermuscular adipose tissue (IMAT), and area were obtained by peripheral QCT scans of the calf (Stratec XCT-2000). Model covariates included age, sex, BMI, diabetes, alcohol intake, smoking, and moderate to vigorous physical activity (MVPA). Linear regression was used to assess the relationship of sleep duration on skeletal muscle.
Results:
Mean sleep duration was 5.5 hours/day (Min 2.2, Max 11.6). Overall, participants were aged 58.7 years, had a BMI of 30.2 kg/m
2
, spent an average of 42 min/day in MVPA, and 18% were diabetic. In fully adjusted models, longer sleep duration was associated with smaller muscle area, but greater muscle density and less IMAT (all P<0.03). There was no interaction of sleep and sex on muscle density, area and IMAT (p-value=0.5184; 0.2730; 0.0954).
Conclusions:
In African Caribbean men and women, longer sleep duration was associated with less myosteatosis, as well as, less muscle area at the calf. Further research is warranted to understand this relationship longitudinally in order to determine how it may inform lifestyle guidelines in the Caribbean.
Hepatic and Skeletal Muscle Adiposity Are Associated with Diabetes Independent of Visceral Adiposity in Nonobese African-Caribbean Men
