This is an interesting looking discussion paper. Lack of adequate appreciation of physical exercise's complexitiescan pre-empt appropriate design and interpretation in scientific discovery. I've not read the whole thing, but this statement stood out in the abstract: Normal physiological processes are dynamic, integrated, periodic, and therefore, it is difficult to define normal physiological function by looking at a single time point or single process in a non-stressed subject. The paper is challenging this idea of an exercise pill - this concept that a drug could be developed to mimic the beneficial effects of exercise. The authors object: The concept of an "exercise pill/exercise mimetic" demonstrates an inadequate appreciation for the complexities in integrating cell, tissue, organ, and systems during both acute disruptions in homeostasis by a single bout of exercise, and longer-term chronic adaptations to different types of exercise such as resistance and endura...