Physical activity bouts and sleep duration are key predictors of cardiometabolic risk in Black adults

Background/Introduction Twenty-four-hour movement behaviours i.e., inactivity, physical activity (PA), and sleep duration (SD), are key determinants of cardiometabolic health. However, evidence of these links in UK Black adults remains limited. Purpose This study evaluated the impact of daily activity bouts on cardiometabolic risk severity in in this population. Bouts were defined as continuous periods of moderate-to-vigorous physical activity (MVPA) lasting 1–5 minutes, 5–10 minutes and 10 minutes representing brief episodes of movement that interrupt sedentary behaviour without reaching the duration typically associated with structured exercise. Methods Seventy-five UK Black adults (51% female; mean age: 40 ± 10 years old) with no self-reported history of cardiovascular or metabolic disease were recruited. Participants wore a wrist accelerometer for nine days, to quantify daily inactivity, light physical activity (LPA), MVPA, and sleep duration (SD). Cardiometabolic risk severity was assessed using a continuous metabolic syndrome score (cMetS) derived from z-scores for waist circumference, systolic blood pressure, random glucose, non-HDL cholesterol, and HDL cholesterol. Associations and prediction models were explored between accelerometry and cardiometabolic risk variables using Pearson correlations and multivariable linear regression. Results Participants spent 672 ± 139 mins/day inactive, 112 ± 46 mins/day in LPA, 96 ± 57 mins/day in MVPA whereas sleep duration was 346 ± 102 mins/day. MVPA in bouts of 1–5 mins, 5-10 mins, and 10 mins were 25 ± 17 (male: 29 ± 18 vs female: 20 ± 14, p=0.03), 11 ± 10 (male: 15 ± 12 vs female: 8 ± 7, p=0.003), and 21 ± 19 (male: 27 ± 20 vs female: 16 ± 18, p=0.01) minutes, respectively. Mean cMetS was -0.04 ± 0.53 (males: 0.09 ± 0.55 vs females: -0.18 ± 0.48). ST (≥30 min bouts) were positively associated with cardiometabolic risk severity (cMetS) (r = 0.25, p = 0.04, with a stronger effect in females (r = -0.35, p = 0.04) compared to males (r = 0.20, p = 0.22). MVPA in short bouts (1–5 min) showed an inverse association with cMetS (r = -0.28, p < 0.05; female: r = -0.41, p = 0.01, male: r = -0.35, p = 0.04). No significant associations were observed for MVPA bouts >5 min. Sleep duration was also inversely related to cMetS (r = 0.27, p < 0.05), with stronger associations in females (r = -0.368, p = 0.025) than males (r = -0.165, p = 0.351). In adjusted regression models, MVPA (1–5 min) [β = -0.26, p = 0.035], sleep duration (β = -0.30, p = 0.012), and inactivity ≥30 min (β = 0.25, p = 0.035) were independent predictors of cMetS. Conclusion Short moderate-to-vigorous physical activity bouts and sleep are linked to lower cardiometabolic risk in UK Black adults, whereas prolonged periods of inactivity increase risk. Associations were stronger in women, suggesting that small, frequent movement breaks may confer greater benefit in this group.