The 6 greatest fat-torching outdoor workouts of all time

Rock Climbing Outdoors

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.

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6. Mountain biking

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 Red Bull Rampage. “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 in the pedals when riding through obstacles to spare yourself some of the beating.

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5. Rock climbing

The whole world melts away when you’re high up on a rock face, with nothing between you and the deck but 10mm of rope and your grip on the rock. And that’s what’s beautiful about rock climbing: There are no full-length mirrors, no babes to impress, and—thank God—no Nickelback looping over a sound system. It’s just you, your partner, the route, and, in many cases, killer views. “I love the individual challenge,” says Kris Peters, who’s made a name for himself training world-renowned rock climbers like Daniel Woods and Emily Harrington. “It’s you against the rock up there, and it’s an incredibly self-satisfying feeling when you complete something you’ve worked so hard for.” To get started, find a guide and take a class or two that’ll get you up on real rock on Day 1 and give you a feel for the sport. If it suits you, get more practice at a climbing gym and, in the process, look for a more experienced partner who’ll literally show you the ropes.

What it works: “Climbing is a very upper-body-dominant sport—grip strength, finger strength, pulling strength from your lats,” says Peters, whose Black Mountain Training specializes in climbing- and mountaineering-specific strength. “The three biggest muscle groups that are going to get worked are biceps, lats, and forearms.”

Calorie burn: 837 per hour

Pros: Climb enough, and your upper body will be rock hard, as if it, too, were chiseled from stone. Because of the intense mental focus and physical effort it requires, climbing is almost like a workout combined with meditation. You clear your head and work the route, and when it’s done you’ve accomplished something incredible while getting ripped.

Cons: “On outdoor rock, you’re always going to need a climbing partner and a ton of gear,” says Peters. “And the gear is wicked expensive.” And unlike running or, say, riding a bike, it takes a serious time investment to learn the sport and get started. Plus, access to outdoor rock is quite limited. “That’s why a lot of people go to the gym—all you need is your harness and your shoes, since most gyms already have a belay device, ropes, and everything else you need.” Also, lots of climbers have skinny legs for a reason (the greater your leg mass, the greater the hindrance it has on steeper climbs; you’re hauling your own body weight after all). And then there’s the considerable fear factor of dangling from a rope high off the ground. Try to remember that climbing is a technical sport—dependent on strong ropes that are anchored to a system that will support your fall—and not a risky one, so long as you climb within your limits and, most important, follow safety protocols.

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4. Open-water swimming

We’ve all heard what a great fat-burning exercise swimming is, but most of it happens in the pool, where swimming endlessly back and forth, focused on lane patterns, is even more monotonous than the treadmill. Taking the swim outside lets you actually get somewhere—like across a lake or river or bay—and environmental factors add challenge, not to mention the “no turning back” motivational approach, to the workout.

What it works: Each stroke in the water works your shoulders and upper back, while pulling the water hits your lats and triceps hard. Don’t forget the hamstrings, quads, and glutes, which are largely responsible for your kick. And, because you need to practice breath control while working major muscle groups, it’s a hell of an aerobic exercise that can leave your muscles and lungs screaming.

Calorie burn: 694 per hour

Pros: “Swimming is a full-body workout,” San Diego-based triathlon swim coach Kevin Koskella says, “without the pounding of running or the danger of cycling with traffic.” It’s a long, steady swim since “you don’t get that flip turn every 25 or 50 meters where you can push off the wall and glide.” You also won’t send your heart rate as high as running, which means it’s even better for burning fat.

Cons: Even Koskella felt like a fish out of water when he first started open-water swimming. “There are so many more elements out there,” he says. “You don’t have walls or lane lines to follow. And you usually can’t see what’s below you, either, so the fear of the unknown is a big factor.” Ocean currents and riptides can come into play depending on your local geography, so be sure to educate yourself before heading out. There’s a lot more to get used to—navigating by sight, lengthening your stroke to conserve energy, breathing more efficiently, and calming your nerves—but that comes with practice. “Get into a breathing pattern you’re comfortable with and focus on counting your strokes,” Koskella advises, “which will put your mind in a meditative state as you swim.”

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3. Obstacle-course racing

Imagine running a brutal cross-country race over rugged terrain. Then you sling a 50-pound sandbag over your shoulders and put in a huge anaerobic effort hauling it up a mountain. Then you’re back to running, only now your legs are heavy and wooden, your muscles tweaking. Next you leap into freezing-cold ice water that makes your legs full-on cramp. Now you’ve got to jump up and scale a wall, but your calves are no longer firing, they’ve shut down. That’s obstacle-course racing (OCR), and—oh, right—there are 20 more obstacles between you and the finish line. “It’s in those moments that you’ve got to dig deep and find strength within yourself,” says David Magida, one of the sport’s first pro athletes and the recent author of The Essentials of Obstacle Race Training. Yes, what once looked like a mud-splattered fad of people taking the scenic route to a drinking party is now a real, grueling sport (with professional athletes), and a growing one at that. “That’s what makes the sport so beautiful—you find out a lot about yourself over the course of a race.”

What it works: Because of the event-based nature of OCR, it’s more a way of testing fitness than of building it. “It’s all about being challenged by a race that tries to break you down from every facet of fitness imaginable—strength, power, endurance, speed, agility, mobility and, just as critical, recovery,” Magida says. “It tests you, it pokes holes in your fitness, and challenges you to correct them so you can be better the next time you line up.”

Calorie burn: 552 per hour

Pros: The “R” in OCR stands for “race,” so straight-up speed is important, but all of those strength obstacles—heavy carries, wall climbs, monkey bars, and the like—tend to level the playing field for guys who do a lot of strength work. And the races are fun! “I think we were designed to run, to jump, to climb, to move, to get dirty,” Magida says. “It makes you feel like a kid again, but it also kind of makes you feel like a man at the same time.”

Cons: OCR sounds like a prison escape, as it’s more than just a test of strength, endurance, and speed; it’s a test of toughness. Crawling through mud beneath barbed wire, hefting yourself over high wooden walls, running through charged electrical wires, jumping into grimy water—you’re bound to get bruised and battered. And then there’s the fitness beatdown: “By the time you cross the finish line, you’re crushed,” Magida says. “You’re sore for days.” And while the equipment may be minimal, race entry fees often start near the triple digits.

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2. Road cycling

America has 2.68 million miles of paved roads—enough to circle the equator 107 times!—to explore, and, on a bike, the adventure begins right outside your door. And while there’s long been a perception of elitism in roadie culture, that’s disappearing, replaced now by a more welcoming community. “Nowadays, you finish the ride, you high-five your buddies, you grab a beer, and you’re stoked—that’s the new norm,” says recently retired pro cyclist Ted King. Fitness, beer, and stoke? Sounds like a winning combination.

What it works: One look at a professional road racer’s tree-trunk quads and carved-from-granite leg definition is proof enough this is a lower-body workout. King makes the case that “if you’re really pumping your bike in a sprint, there’s plenty of upper body to be done,” but sprints last only a matter of seconds. Still, there’s a huge variety of leg workouts to do on a bike, from strength-building SFRs (slow-frequency repetitions) to sprint intervals, and hill climbs.

Calorie burn: 816 per hour

Pros: You can cover a lot more ground on a road bike, which is the fastest, most efficient mode of human-powered travel. And because it’s more efficient, King says, “you can do a ton of work in a one-hour ride—you can sprint, you could do SFR, you could do endurance, you could do whatever—and that’s going to be much more efficient than a comparable one-hour run” that would leave your body wasted for days.

Cons: “You have to get over the fact that you’ve got to wear spandex,” King quips, “and you’re only going to look cooler when you shave your legs.” So there’s that to deal with, and traffic. Plus, cycling gear isn’t cheap. (Plan to spend at least $1,000 on a solid entry-level steed.) Racing technology is advancing at a Tour de France–worthy pace, though plenty of that tech trickles down to beginner bikes, meaning you can get more bike for your buck than ever before.

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1. Trail running

When pounding pavement starts to grind on your nerves and joints, it’s time to lose yourself on the local trails. Exploring wilderness on your own two feet is “very raw and very natural, and that’s what inspires me,” says pro trail runner Max King. That, and the fact that it takes your stale cardio routine to the next level, building a more full-body fitness than the treadmill could ever hope to. “Outside, you’ve got undulating trails, you’ve got hills, you’ve got uneven terrain and uneven footing,” says King, “so [trail running] works those stabilizing muscles in a way that you don’t get from the very repetitive motion of running on a road or treadmill. It takes that basic runner and fills him out into a more complete athlete.”

What it works: As with any kind of running, trail running is primarily going to work your lower body—quads, glutes, hamstrings, and calves. But irregular terrain—riddled with roots, rocks, and other obstacles—and softer surfaces require you to use more stabilizer muscles and connective tissue and engage your core muscles for stability.

Calorie burn: 735 per hour

Pros: Dirt running is dirt cheap, since the only gear you need is a pair of trail shoes ($100 to $150). Plus, softer surfaces and uneven terrain mean fewer of the overuse injuries that typically plague runners (hello, runner’s knee), though there are environmental factors—more exposure, falling hazards, animal encounters—that, depending on your outlook, can be seen as very good. And you burn up to 10% more calories than on concrete.

Cons: Finding a trail isn’t nearly as easy as stepping out your front door. They’re almost everywhere, from rugged mountain ranges to local city parks, but seeking them out takes time and effort. Also, King points out, “it’s still just running.” There’s enough lower-body work to beef up your chicken legs, but you’re still not hitting your upper body much. King supplements trail runs with core work, upper-body weight training, and rock climbing. And, well, if you really don’t like running, you probably won’t like it any more in the boonies.

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