Athletes have always trained. But in recent years, that training has become much more sport and skill specific, and athletes are using a host of biometric sensors to measure everything from strength and fatigue, to the quality of a night’s sleep. The result: The best are getting better. But everyone else is getting better too. “That’s actually the biggest change in performance over the past few decades — it’s not so much that the best of the best are so much better as that so many people are so extraordinarily good.” And these tools are coming to a body part near you. From The New Yorker’s James Surowiecki: How the performance revolution came to athletics — and beyond.