I'm a passionate runner, and always considered cycling as something fun, e.g. mountain-biking, but difficult to practice regularly. There's a lot of overhead in cycling, like the preparation, bike maintenance, dealing with city traffic, etc. Anyway about eight months ago I bought a road bike and felt in love with it. Soon after that I discovered Zwift and that gave an additional dimension to the sport: practice whenever you want from home, with accurate power measurements and a way to socialise with distant people. That was a game changer. In five months I cycled 1600 virtual Km and climbed almost 17 virtual Km. Meanwhile my running performance, instead of degrading, improved, and that surprised me. Anyway what I wanted to write about is a great article I read, "Physiological Differences Between Cycling and Running" . It's a review of articles published in that area. Some conclusions are very interesting. In general it seems sports medicine is still inconclusive...