Face it, pressing dumbbells and churning away on the elliptical machine are good exercise, but they're not exactly great fun if that's all you do day in and day out. That's why adventuresome outdoor activities like trail running, mountain biking, and triathlons have exploded in popularity. The tide of exercise enthusiasts getting their daily dose of fitness outside is so great that the United States Adventure Racing Association (USARA) reports that adventure racing-events that involve sports like canoeing, mountain biking, and off-road running-has been growing at an average rate of more than 600% a year for the past 5 years.
And it's not just elite, hard-bodied pros out there getting down and dirty. The lion's share of these sports' roaring growth is from everyday computer jockeys who prefer their fitness with a little fresh air. "These sports are challenging, fun, and wonderfully social," says Georgia adventure-racing coach Michael George. "And there are so many great entry-level events that weekend warrior types have the chance to get a taste of multi-sport races without making a huge training commitment."

Even if you never pin on a race number, you can still participate, get fit, and have fun. Here's what you need to know to get started.

TRAIL RUNNING
Running on anything from groomed paths to rocky forest trails.

What you need: Trail shoes. You'll run more comfortably and prevent injury with trail shoes, which are designed with more ankle stability, grippier traction, and more sole protection than road shoes. They're available at most any running shoe store. If you plan on running longer distances (anything more than 45 minutes), you'll also want a hydration pack, a waist belt that holds water, snacks, and other personal belongings.

The buzz: Slower paced and more meditative than road running. Dirt, wood chips, and cinders are easier on your joints and muscles than concrete and pavement. Builds more balanced strength because you use your muscles in a greater range of motion off-road.

Your first time out: Ease into it. Look for a relatively flat trail without too many rocks, roots, or other obstacles. Start by working 1- to 2-minute jogging intervals into a 30-minute hike. Each time you go out, increase your running time slightly. As you get comfortable in the sport, you can run longer and on more challenging trails.

Get going: You can find local trails in your area from the All American Trail Running Association. Check out their listings of trails and races at www.trailrunner.com. Or ask the folks at your local running shop to recommend popular trails and paths.

MOUNTAIN BIKING
Riding a bike off-road on dirt roads, cinder paths, and forest trails.

What you need: an off-road bike. A hybrid (a slightly beefier bike you can ride on pavement or dirt roads) will do if you stick to flat, smooth paths; anything more challenging will require a fat-tired mountain bike.

The buzz: Exhilarating. No worries about traffic. Better total-body workout than stationary or road cycling. And you can feel like a kid getting muddy.

Your first time out: Mountain biking can be risky, depending on how "technical" the trails are. Paths with lots of roots, rocks, logs, and steep climbs and descents will be more difficult than wide, rolling cinder paths or dirt roads. Start simple, and ride with a friend.

Get going: Talk to the operators of your local bike shop to find good places to ride near you. They can help you find a location that best suits your ability. For more information on trails in your region, you can also check out www.gorp.com.