Purpose: Gut symptoms and markers of gut dysfunction have been observed in patients with Chronic Obstructive Pulmonary disease (COPD). It remains unclear whether walking exercise induces disturbances in protein digestion and amino acid absorption and whole body protein kinetics in these subjects due to exercise induced hypoxia. Methods: Sixteen clinically stable patients with moderate to very severe COPD and 12 age matched control subjects completed the study. Protein digestion and amino acid absorption and whole body protein kinetics, in the postabsorptive state, were measured via a continuous infusion of stable tracers in combination with orally administered tracer sips during 20 minutes of walking exercise and up to 4 hours post-exercise. COPD patients completed one study day, walking at maximal speed, while healthy subjects completed two, one matched to the speed of a COPD patient and one walking at maximal speed. Results: The COPD patients tolerated 20 minutes of vigorous intensity walking despite elevated heart rate (P<0.001) and substantial desaturation (P<0.001). Relative to rest, protein digestion was increased during recovery from exercise (P<0.05) while amino acid absorption was reduced during (P<0.0001) and immediately after exercise (P<0.001). Whole body protein breakdown was reduced within 20 minutes after exercise (P<0.05) and stayed suppressed for four hours (P<0.0001). Whole body net protein breakdown was elevated for four hours post-exercise (P<0.001). Conclusion: Our data showed that 20 minutes of walking exercise is sufficient to cause substantial perturbations in gut function in older adults and COPD patients with hypoxia as a potential underlying factor.

中文翻译：

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步行运动会改变患有和未患有 COPD 的老年人的蛋白质消化、氨基酸吸收和全身蛋白质动力学

目的：在慢性阻塞性肺病 (COPD) 患者中观察到肠道症状和肠道功能障碍标志物。由于运动引起的缺氧，步行运动是否会在这些受试者中引起蛋白质消化和氨基酸吸收以及全身蛋白质动力学的障碍仍不清楚。方法：16 名临床稳定的中度至极重度 COPD 患者和 12 名年龄匹配的对照受试者完成了研究。在步行运动的 20 分钟和运动后 4 小时内，通过连续输注稳定的示踪剂与口服示踪剂啜饮，测量吸收后状态下的蛋白质消化和氨基酸吸收以及全身蛋白质动力学。COPD患者完成了一天的研究，以最大速度行走，而健康受试者完成了两天，一种与 COPD 患者的速度相匹配，另一种以最大速度行走。结果：尽管心率加快（P<0.001）和饱和度降低（P<0.001），COPD 患者仍能耐受 20 分钟的高强度步行。相对于休息，运动恢复期间蛋白质消化增加（P<0.05），而氨基酸吸收减少（P<0.0001）和运动后立即（P<0.001）。运动后 20 分钟内全身蛋白质分解减少（P<0.05）并保持抑制 4 小时（P<0.0001）。运动后四小时全身净蛋白质分解升高（P<0.001）。结论：