You might remember Eva Twardokens as a ski racer (two-time Olympian, six-time national champion, bronze World Cup medalist). But these days, she’s setting new American records as a weightlifter, thanks to a fitness program called CrossFit. CrossFit is “constantly varied, high-intensity functional movement," which is to say: less fancy machinery, more old-fashioned rope-climbing, sand-bag lifting, kettle-bell throwing, etc. (Think Sylvester Stallone yoked to a plough in Rocky IV.) Though CrossFit has been around for almost a decade, it’s recently enjoyed a surge of followers.