Effect of Sedentary Time and Skeletal Muscle Mass on ABI-Based Vascular Status Classification in Women in Their 20s

This study examined associations between sedentary time and skeletal muscle mass with ankle– brachial index (ABI_R)-based vascular status (normal vs. abnormal) among young adult women. Health screening data from 49 women in their 20s were analyzed, with participants classified as normal (ABI_R 1.1–1.3; n = 23) or abnormal (ABI_R ≤ 1.0; n = 26). Two cases with missing sedentary time were excluded (n = 47). Independent-samples t tests, logistic regression, and receiver operating characteristic (ROC; AUC) analyses were conducted, and a classification and regression tree (CART) model (70/30 split, seed = 42, maximum depth = 3) was used to explore potential cutoffs. Sedentary time tended to be longer in the abnormal group (8.38 ± 3.67 vs. 6.31 ± 4.05 hr/day; p = .076), whereas skeletal muscle mass was significantly lower (23.10 ± 3.20 vs. 21.45 ± 1.84 kg; p = .036). Logistic regression revealed trend-level significance for sedentary time alone (Model 1: OR = 1.162, p = .080), with both sedentary time (OR = 1.228, p = .033) and skeletal muscle mass (OR = 0.697, p = .021) significant in the combined model (Model 2). Model performance improved in Model 2 (Nagelkerke R² = .273, AUC = .727) compared to Model 1 (R ² = .095, AUC = .675). In CART, sedentary time of 4.5 hr/day was selected as the first split, showing 93.3% test accuracy (14/15) but requiring cautious interpretation. These findings suggest that longer sedentary time and lower skeletal muscle mass may jointly contribute to abnormal ABI_R classification in young women.