More tactical than racquetball, which is played on the same courts, faster than tennis, and demanding more precision and stamina than any racquet sport, handball is the ultimate court game. Many who try it just once throw their bruised hands up in frustration, but most who stick with it a while become permanent converts. And it burns fat tissue better than a spa weekend in the second ring of hell. "Handball has a long learning curve," says Bernie Samet, the Olympic's handball and squash director, as he watches each lunge with clinical detachment. "Learning to anticipate where the ball will end up isn't easy. Timing and technique are everything. But handball gets in your blood. The great thing about my job is that when three players need a fourth, I'm always around. They ask me, and it's like putting heroin in front of an addict."

The Benefits
Even if you don't succumb to the handball jones--like the 90-year-old Olympic Club member who plays every Tuesday--its value as an off-season surrogate for your your favorite outdoor sport is hard to beat. Whether your primary sport emphasizes endurance, agility, coordination or quickness, handball will maintain or improve on what you've got. Hall-of-Fame NFL quarterback George Blanda credits the sport for keeping him fit and effective well into his 40s. A University of Utah study showed handball to be superior to racquetball--a sport that's no stroll in the park--in all four of the fitness indicators that were measured: calories burned per hour (751 vs. 644), average heart rate (164 vs. 137), average oxygen uptake (30.1 vs. 25.8), and average ventilation rate (85.9 vs. 70.9). Handball is harder work than other racquet sports because without the force of a racquet behind it, the ball travels slower, which means more running to get to it. "I've played lots of racquetball, and the physical demands of handball are much greater," says LeAnn Martin, a women's doubles handball champion with a kinesiology doctorate.

While the benefits of handball are many, the risks are few. "It's a relatively injury-free sport," says Dr. John Aronen, U.S. Handball's sports-medicine consultant. "Most injuries that do occur are muscle strains in the shoulder, elbow and back, but those are avoidable if you follow a basic conditioning, strengthening and stretching program." Impact injuries are surprisingly rare, although overexuberant players have been known to dislocate fingers charging into side walls. The most unique aspect of the sport is summarized by the bumper sticker "Handball Players Do It With Both Hands." Developing coordination and power in your non-dominant, or "off," hand takes time, but if you don't become semi-ambidextrous, your opponent is certain to exploit your weak side. This is the hardest part of handball to pick up, but also what sets it apart; every other sport neglects your weak arm. Accuracy is also crucial. Martin compares handball to golf. "Both are extremely challenging to play well," she notes, "because they involve striking a small ball with a great deal of precision. The additional challenge of handball is that the ball is moving when you hit it." Also like golf, taking your eye off the ball may be the most common beginner's error.

The History
Here's one more similarity between golf and handball: Both date back to 15th-century Scotland, where King James I played a form of handball in his castle cellar in 1427. By the 1500s, it was played widely in Ireland. Irish immigrants brought it to New York City and San Francisco in the 1880s, when handball play commenced at the Olympic--North America's oldest athletic club.

The Rules
Racquetball was modeled after handball, so the rule differences are minor. The same courts are used, with six surfaces--floor, ceiling and all four walls--in play. Here's a rules synopsis: After a coin is flipped for first serve, two serve attempts are allowed from the "service box." The ball must rebound in the back half of the court, cannot bounce on the floor more than once between shots, and must hit the front wall with each shot. It can be banked off the ceiling, side walls and back wall--the tricky geometry portion of play. The server scores a point if the rally is won, or loses serve if it's lost. The first two games are to 21, with a tie-breaking third game to 11 if needed. Singles or doubles can be played.

The Technique
Here's how to avoid looking silly your first time out. Sling it: Your hands should be cupped, like you're holding a ball, to disperse the impact. When you make contact with the ball inside the "cup," let it roll off your palm and then off the two fingers next to your thumb--the fingers you use to aim a thrown ball. The motion should be just like throwing as your elbow flings forward before you "sling" the ball. Never slap or bat it--unless you like pain.

Different strokes: The sidearm is your power stroke and is similar to skipping a rock on a pond. Crouch low to make either of these rally-ending sidearm shots: a "kill shot" (a line drive so low to the floor that your opponent can't get to it before it bounces twice) or a "passing shot" (placing the ball out of an opponent's reach). The other most common shot is the "overhand," which is comparable to pitching a baseball. It's primarily a defensive shot, however, because it usually keeps the ball bouncing high and slow, instead of low and fast. Footwork: Without the benefit of a racquet's reach, you'll need to run to the ball more than you do in racquet sports. Try to get to a position two steps behind the point where you expect to strike the ball. This will let you adjust for miscalculations and step into the shot. Also, like a tennis player, edge forward the moment your opponent is serving to be ready to spring toward the ball.

The Essentials
David Chapman, 25, doesn't rely on power like fellow St. Louis sports star Mark McGwire. Chapman is America's best handballer because he's a master strategist who mixes up his shots the same way a veteran pitcher mixes his pitches. "Conditioning and thinking are the two keys," says Chapman. "I draw out rallies to wear my opponents down, and I use strategy to win points. You need to develop a sense of where the ball will go after each bounce--which comes with experience--and be in good all-around shape." The latter is necessary because rallies between top players can last for dozens of shots--far longer than in racquetball, in which putting the ball away early is standard.

The Competitive Sport As the leading pro, Chapman pockets about $35,000 a year, less than he earns from his "real job" at an auto dealership. It ain't no glamour sport, but there's an age group for everyone, including handball aficionados Bill Cosby and Ed Married...With Children O'Neill. The Web site of U.S. Handball (520-795-0434), www.www.ushandball.org, contains rules, instructional articles and links, along with directories of clubs, players and tournaments. There are about 40,000 regular four-wall players in the U.S., and a smaller number who play one of the outdoor-handball variations: one-wall, which is big in New York City, and three-wall, popular in California and Florida. Four-wall handball's major advantage is that it can be played on any racquetball court. There are 3,000 of those, most at racquet and health clubs, YMCAs and universities.

The Brotherhood
Handball is small enough that players regard it as a fraternity. But veterans, hungry for new blood, greet rookies like old pals. And the sport is big enough that it isn't difficult to find an opponent. Clubs of 100-plus handball regulars are established in 14 U.S. cities, ranging in size from New York to Tucson. Handball is also popular in Canada, Mexico, Ireland and Australia. Instruction is available at many clubs where the game is played, so what's your excuse? Get out of the weather, on to a court and give it a fling. Beats the hell out of a treadmill. Freelance writer Bob Cooper is a frequent contributor to Men's Fitness.