The 6 Greatest Outdoor Workouts, Period

After a dark and cold winter, the fluorescent-lit gym starts to feel as drab and stuffy as a fluorescent-lit cubicle, and the old routines of arm day and leg day and ab day just aren't cutting it. Ditch the racks and benches and venture outdoors into the sunshine. Your bleary eyes will find life's better with the wind in your hair, the sun on your back, and the world zipping past. We've ranked the top outdoor sports mountain biking, trail running, open-water swimming, obstacle course racing, road cycling, and rock climbing - based on exercise efficacy, calories burned, cost of gear, availability, and risk factor to see which one offers the most burn for your buck. So, go ahead and take your fitness to the next level while communing with nature. The outdoors awaits. Go work it.

- PETER KOCH

6 Mountain Biking

TAKE A WILD RIDE

For a lot of guys, "mountain biking" conjures up images of adrenaline junkies in full-face helmets rocketing down white-knuckled descents and hucking themselves off cliffs à la Tygerberg Trails. "It's not necessarily gnarly", says seven-time world champion endurance mountain biker Rebecca Rusch. "It's like skiing, where you can choose a green, blue, or black trail depending on your skill level." For her, mountain biking is all about leaving the road behind and exploring. "It's easy to say, 'I want to see what's over that hill' or 'I've never been in that valley over there, so I think I'll check it out'. I really like the distance you can cover on a bike; you see so much more."

WHAT IT WORKS

"Endurance heart and lungs is something people in the gym neglect", says Rusch. Dirt riding hits more than just legs. "If you're riding really technical trails, it's a ton of upper body, core, and midsection."

CALORIE BURN 694 per hour

PROS Besides for the downhill bits, mountain biking, done right, is low-impact. If there's an obstruction like a large rock, you can get off your bike, walk around it, and keep going. It's also mentally engaging "because you're constantly looking ahead and making choices about picking a line, standing or sitting, and shifting gears".

CONS Your ass will probably hurt from rattling over roots and rocks, so stand up on the pedals when riding through obstacles to spare yourself some of the beating.

5 Rock Climbing

GET A GRIP