This study examined the mediating effect of total body fat mass, lean mass, blood pressure (BP) and insulin resistance on the associations of sedentary time (ST), light physical activity (LPA) and moderate-to-vigorous PA (MVPA) with carotid-femoral pulse wave velocity (cfPWV), carotid intima-media thickness (cIMT) and carotid elasticity in 1574 adolescents from the Avon Longitudinal Study of Parents and Children birth cohort, UK. ST, LPA and MVPA were assessed with ActiGraph accelerometer. ST and LPA were sex-categorised in tertiles as low (reference), moderate and high, while MVPA was categorised as <40 min/day (reference), 40–<60 min/day and ≥60 min/day. cfPWV, cIMT and carotid elasticity were measured with Vicorder and ultrasound. Fat mass and lean mass were assessed with dual-energy X-ray absorptiometry and homeostatic model assessment of insulin resistance (HOMA-IR) was computed. Mediation analyses structural equation models and linear mixed-effect models adjusted for cardiometabolic and lifestyle factors were conducted. Among 1574 adolescents [56.2% female; mean (SD) age 15.4 (0.24) years], 41% males and 17% females accumulated ≥60 min/day of MVPA. Higher ST was associated with lower cIMT partly mediated by lean mass. Higher LPA (standardized β = −0.057; [95% CI −0.101 to −0.013; p = 0.014]) and the highest LPA tertile were associated with lower cfPWV. BP had no significant mediating effect movement behaviour relations with vascular indices. Lean mass partially mediated associations of higher MVPA with higher cIMT (0.012; [0.007–0.002; p = 0.001], 25.5% mediation) and higher carotid elasticity (0.025; [0.014–0.039; p = 0.001], 28.1% mediation). HOMA-IR mediated the associations of higher MVPA with higher carotid elasticity (7.7% mediation). Engaging in ≥60 min/day of MVPA was associated with higher carotid elasticity. In conclusion, higher LPA was associated with lower arterial stiffness, but higher MVPA was associated with thicker carotid wall explained by higher lean mass.

本研究探讨了全身脂肪量、去脂体重、血压 (BP) 和胰岛素抵抗对久坐时间 (ST)、轻度体力活动 (LPA) 和中度至剧烈体力活动 (MVPA) 与英国雅芳父母和儿童出生队列纵向研究中 1574 名青少年的颈动脉-股动脉脉搏波速度 (cfPWV)、颈动脉内膜-中层厚度 (cIMT) 和颈动脉弹性。ST、LPA 和 MVPA 使用 ActiGraph 加速度计进行评估。ST 和 LPA 按性别分为低（参考）、中和高三分位数，而 MVPA 则分为 <40 分钟/天（参考）、40-<60 分钟/天和≥60 分钟/天。使用 Vicorder 和超声测量 cfPWV、cIMT 和颈动脉弹性。使用双能 X 射线吸收测定法评估脂肪量和瘦肉量，并计算胰岛素抵抗稳态模型评估 (HOMA-IR)。进行了针对心脏代谢和生活方式因素调整的结构方程模型和线性混合效应模型的中介分析。1574 名青少年中 [56.2% 为女性；平均 (SD) 年龄 15.4 (0.24) 岁]，41% 的男性和 17% 的女性累计 MVPA ≥60 分钟/天。较高的 ST 与较低的 cIMT 相关，部分由瘦体重介导。较高的 LPA（标准化 β  = -0.057；[ 95% CI -0.101 至 -0.013；p  = 0.014]）和最高的 LPA 三分位数与较低的 cfPWV 相关。血压与血管指数的运动行为关系无显着中介作用。瘦体重部分介导了较高 MVPA 与较高 cIMT（0.012；[0.007–0.002；p  = 0.001]，25.5% 介导）和较高颈动脉弹性（0.025；[0.014–0.039；p  = 0.001]，28.1% 介导）之间的关联。HOMA-IR 介导了较高 MVPA 与较高颈动脉弹性的关联（7.7% 介导）。每天进行 MVPA ≥60 分钟与较高的颈动脉弹性相关。总之，较高的 LPA 与较低的动脉硬度相关，但较高的 MVPA 与较厚的颈动脉壁相关，这可以解释为较高的瘦体重。