These outdoor activities can get you a killer body—without setting foot in the gym.
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Calories burned per hour: about 550
This total body workout targets the arms and shoulders. The gear's not cheap (climbing shoes, rope, carabiners, a harness, webbing, protective devices, and a helmet), so find a school that allows you to rent equipment.
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Calories burned per hour: about 500
Whether you're a pro boarder or can barely make it off the ski lift, this rigorous sport will leave you toned from head to toe (and probably a bit sore the next day). Snowboarding challenges your legs the most, but staying balanced on the board is a great core workout, too.
Photo: FNLAY MACKAY / TRUNK ARCHIVE
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Calories burned per hour: 300 to 350
Rafting is a great upper-body workout—and way more fun than doing dumbbell curls at the gym. Not only does rafting tone your arms, back and shoulders, it’s also a great ab workout since you rely on your core to keep you steady.
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Calories burned per hour: 500 to 700
Ride this celebrity trend (Jennifer Aniston and Kate Hudson are fans!) by hopping on a board, grabbing a paddle, and finding some mellow surf. The hardest part is standing up, but after that, you'll glide your way through the water.
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Calories burned per hour: 500 to 600
Looking for an adrenaline rush? Nothing beats pushing up trails at a hard pace and then whizzing downhill. Plus, biking is great for firming up your biceps, butt, and thighs. For success: Wear a helmet, and stick to trails that fit your experience level.
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Calories burned per hour: about 900
Show off that bikini body by working out in…a bikini! Scuba diving has one of the biggest payoffs of any extreme fitness workout and is a terrific butt, hip, thigh, and ab workout. Many dive shops offer certification courses that teach you to deal with water pressure and maneuver with equipment.
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Calories burned per hour: about 200
Anyone can jump up on a surfboard—staying up is the real challenge. Surfing is not just a great workout that'll tone your core, legs and arms, but it's also a powerful exhilarating experience.
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Calories burned per hour: about 500 (or more)
This winter sport might not involve steep hills, but cross-country skiing is a tough cardio workout that's not for the faint of heart. Gravity isn't helping you here, like it is in downhill skiing; you're legs and arms do all the work to get you around.