The capillary bed constitutes the obligatory pathway for almost all oxygen (O₂) and substrate molecules as they pass from blood to individual cells. As the largest organ, by mass, skeletal muscle contains a prodigious surface area of capillaries that have a critical role in metabolic homeostasis and must support energetic requirements that increase as much as 100-fold from rest to maximal exercise. In 1919 Krogh's 3 papers, published in the Journal of Physiology, brilliantly conflated measurements of muscle capillary function at rest and during contractions with Agner K. Erlang's mathematical model of O₂ diffusion. These papers single-handedly changed the perception of capillaries from passive vessels serving at the mercy of their upstream arterioles into actively contracting vessels that were recruited during exercise to elevate blood-myocyte O₂ flux. Although seminal features of Krogh's model have not withstood the test of time and subsequent technological developments, Krogh is credited with helping found the field of muscle microcirculation and appreciating the role of the capillary bed and muscle O₂ diffusing capacity in facilitating blood-myocyte O₂ flux. Today, thanks in large part to Krogh, it is recognized that comprehending the role of the microcirculation, as it supports perfusive and diffusive O₂ conductances, is fundamental to understanding skeletal muscle plasticity with exercise training and resolving the mechanistic bases by which major pathologies including heart failure and diabetes cripple exercise tolerance and cerebrovascular dysfunction predicates impaired executive function.

毛细血管床构成了几乎所有氧气 (O ₂ ) 和底物分子从血液传递到单个细胞的必经途径。作为最大的器官，按质量计算，骨骼肌包含巨大的毛细血管表面积，这些毛细血管在代谢稳态中起关键作用，并且必须支持从休息到最大运动增加多达 100 倍的能量需求。1919 年，Krogh 的 3 篇论文发表在《生理学杂志》上，将休息和收缩期间肌肉毛细血管功能的测量结果与 Agner K. Erlang 的 O _{2数学模型巧妙地结合在一起}扩散。这些论文单枪匹马地将毛细血管的感知从受上游小动脉支配的被动血管转变为主动收缩的血管，这些血管在运动期间被招募以提高血肌细胞 O ₂通量。尽管 Krogh 模型的开创性特征经受住了时间和随后技术发展的考验，但 Krogh 被认为有助于发现肌肉微循环领域并欣赏毛细血管床和肌肉 O ₂扩散能力在促进血肌细胞 O ₂中的作用通量。今天，在很大程度上要感谢 Krogh，人们认识到理解微循环的作用，因为它支持灌注和扩散 O ₂电导，对于通过运动训练理解骨骼肌可塑性和解决包括心力衰竭和糖尿病在内的主要病理损害运动耐量和脑血管功能障碍预示执行功能受损的机制基础至关重要。