A unique indoor cycling strategy—superfast pacing and push-ups off the handlebars to the beat of bass-thumping music. Diehards liken it to “dancing on a bike.” Just when you think you can’t pedal another second, catch your breath with a bout of hammer curls and shoulder presses in the saddle using 2-pound hand weights. You may also notice familiar faces in your row. Cycle until you reach your four-digit calorie-burning goal. Because your instructor wears a heart-rate monitor, she can tell the class when the tally ticks to 1,000—usually after upwards of 60 minutes.