School of Health and Kinesiology, University of Nebraska at Omaha, Omaha, Nebraska, United States.
Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska, United States.
Am J Physiol Regul Integr Comp Physiol. 2023 Oct 1;325(4):R380-R388. doi: 10.1152/ajpregu.00067.2023. Epub 2023 Jul 17.
Blunted post-occlusive reactive hyperemia (PORH) after prolonged sitting (PS) has been used as evidence of microvascular dysfunction. However, it has not been determined if confounding variables are responsible for the reduction in PORH after PS. Therefore, the purpose of this study was to examine the PS-mediated changes in cardiovascular and metabolic factors that affect PORH using artificial intelligence (AI). We hypothesized that calf muscle metabolic rate (MMR) is attenuated after PS, which may reduce tissue hypoxia during an arterial occlusion (i.e., oxygen deficit) and PORH. Thirty-one subjects (male = 13, female = 18) sat for 2.5 h. A rapid-inflation cuff was placed around the thigh above the knee to generate an arterial occlusion. PORH was represented by the reoxygenation rate (RR) of the near-infrared spectroscopy (NIRS) tissue oxygenation index (TOI) after 5-min of arterial occlusion. An artificial intelligence model (AI) defined the stimulus-response relationship between the oxygen deficit (i.e., ΔTOI and TOI deficit), and RR with 65 previous PORH recordings. If the AI predicts the experimental RRs, then the change in RR is related to the change in the oxygen deficit. RR (Δ -0.27 ± 0.55 lnTOI%·s, = 0.001), MMR (Δ -0.46 ± 0.61 lnTOI%·s, < 0.001), ΔTOI (Δ -0.34 ± 0.62 lnTOI%, < 0.001), and the TOI deficit (Δ -0.42 ± 0.68 lnTOI%·s, < 0.001) were reduced after PS. In addition, strong linear associations were found between MMR and the TOI deficit ( = 0.900, < 0.001) and ΔTOI ( = 0.871, < 0.001). Furthermore, the AI accurately predicted the RRs pre- and post-PS ( = 0.471, = 0.328, respectively). Therefore, blunted PORH after PS may be caused by attenuated MMR and not microvascular dysfunction. Prolonged sitting reduces lower leg skeletal muscle metabolic rate in healthy individuals. Artificial intelligence revealed that impaired post-occlusive reactive hyperemia after prolonged sitting is related to a reduced stimulus for vasodilation and may not be evidence of microvascular dysfunction. Current post-occlusive reactive hyperemia protocols may be insufficient to assess micro- and macrovascular function after prolonged sitting.
长时间坐姿后（PS）的闭塞后反应性充血（PORH）减弱已被用作微血管功能障碍的证据。然而，尚不确定在 PS 后 PORH 减少是否是由混杂因素引起的。因此，本研究旨在使用人工智能（AI）检查影响 PORH 的心血管和代谢因素的 PS 介导变化。我们假设，PS 后小腿肌肉代谢率（MMR）降低，这可能会减少动脉闭塞期间的组织缺氧（即，氧亏缺）和 PORH。31 名受试者（男性= 13，女性= 18）坐了 2.5 小时。在膝盖上方的大腿上放置一个快速充气袖带以产生动脉闭塞。PORH 由近红外光谱（NIRS）组织氧合指数（TOI）的 5 分钟动脉闭塞后的再氧合率（RR）表示。人工智能模型（AI）定义了氧气亏缺（即 ΔTOI 和 TOI 亏缺）与 RR 之间的刺激-反应关系，使用 65 个先前的 PORH 记录进行了定义。如果 AI 预测了实验 RR，则 RR 的变化与氧气亏缺的变化有关。RR（Δ-0.27 ± 0.55lnTOI%·s， = 0.001），MMR（Δ-0.46 ± 0.61lnTOI%·s， ＜0.001），ΔTOI（Δ-0.34 ± 0.62lnTOI%， ＜0.001）和 TOI 亏缺（Δ-0.42 ± 0.68lnTOI%·s， ＜0.001）在 PS 后降低。此外，还发现 MMR 与 TOI 亏缺（ = 0.900， ＜0.001）和 ΔTOI（ = 0.871， ＜0.001）之间存在很强的线性关系。此外，AI 准确地预测了 PS 前后的 RR（ = 0.471， = 0.328）。因此，PS 后 PORH 减弱可能是由于 MMR 减弱引起的，而不是微血管功能障碍。长时间坐姿会降低健康个体的小腿骨骼肌肉代谢率。人工智能显示，长时间坐姿后闭塞后反应性充血受损与血管扩张的刺激减少有关，可能不是微血管功能障碍的证据。目前的闭塞后反应性充血方案可能不足以评估长时间坐姿后的微血管和大血管功能。
