The trampoline isn't just a playtime favorite for kids: In fact, bouncing on the springboard is one of the best low-impact cardio workouts out there: It's both fun and effective for torching calories and building muscle. You can combine bouncing with moves like twists, sprints, jumps, high knees, leg lifts, and weights to get your heart rate up and work your entire body. For proof, Women's Health's fitness director Jen Ator hit up a bounce cardio class to test the benefits firsthand. On her wrist is a Fitbit Versa\u2122, the all-new health & fitness smartwatch from Fitbit. The savvy smartwatch tracks your heart rate 24/7, which helps you optimize your calorie burn. Plus it features phone-free music, 15+ exercise modes, and the guided breathing sessions \u2013 all with 4+ day battery life*, so you can crush your fitness goals every day. #workoutbuddygoals, anyone?Ready to start jumping? Here are some tips before takeoff:Work off the trampoline first. To get used to the motion, start by practicing small hops and stretches on the ground. Keep your height in check. You don't need to be aiming for the ceiling; the higher you jump, the more prone to injury you'll be, so keep your bounces small. Control your movements. The trampoline is unstable (oh hello, ab workout), so you should focus on controlled movements. That way, you won't misstep or tweak anything as you go. Browse the New Fitbit VersaFrom the videoShot on location at Bari Studio, NYC. Workout outfit: Fitbit Versa, starting at $199.95, fitbit.com. Heroine Sport Tank, $135, netaporter.com; Heroine Leggings, $170, netaporter.com* Battery life varies with use.