How Elite Tennis Players Crank Out Serves at 150 MPH

It’s early afternoon in Orlando, the hottest time of day on a characteristically sultry Wednesday in Florida, a state famous for its perennially warm, wet, shirt-soaking conditions, which just so happen to be pretty much perfect for playing tennis. Or so I’m told. I’m standing—sweating, squinting, panting—at the opposite end of a court from 21-year-old …