Functional MRI experiment published in Physiological Reports

In this human exercise physiology study, three different imaging modalities (ultrasound of the popliteal artery, blood-oxygen-level-dependent magnetic resonance imaging, and near infrared spectroscopy) evaluated calf muscle microvascular physiology during exercise. Blood-oxygen-level-dependent signal intensity in the gastrocnemius muscle decreased at higher workloads despite greater popliteal blood flow, indicating improved oxygen extraction. The full article can be found at: https://www.ncbi.nlm.nih.gov/pubmed/27798357