A brawny man in black stretch pants and a pirate-style headcloth eyes the sparring bag icily, bounces slightly, pivots and rockets a leg into the bag.
"WAP!" He delivers one kick. Then another. And another.
"He's kicking with about 300 pounds of pressure," said coach Lionel Taylor. "We have to replace the bag every 15 days."
A disquieting thought, when you realize that in competition, kicks like that combined with left hooks and right crosses land on other youths' torsos -- repeatedly. Which explains the no-nonsense mood of the youths who practice kickboxing three times a week in the cinderblock room of Langley Recreation Center.
"Drop your hands for one minute and you're going to sleep," said Taylor, a Recreation Department leader and a former professional kickboxer.
Part of a martial arts system known as Bando, kickboxing has been around since the 16th century. Popular in Myanmar (formerly Burma), Japan and Thailand, it was introduced in this country in 1960 and has taken hold steadily.
Taylor has taught the art to youths from Northeast Washington's mean streets for 15 years, steering many away from drugs and crime. The sport's rigorous conditioning and mental discipline leaves little time for, in Taylor's words, "hanging on the corner."
Along the way, Taylor has also groomed some champs. His star pupil, Bryan Ashton, is a four-time national champion.
Next month, Ashton, a junior at Spingarn High School, will travel to Grenoble, France, to compete in an international tournament.
A row of grim-faced boxers, bent at the waist, stare straight ahead and begin swinging taped hands from side to side, a pugilistic Chorus Line from Hell.
"Ready, move!" shouts assistant coach Cole Bryant. The boxers step forward, jab with their left fists, follow with right hooks, the squeaks of their pivoting sneakers filling the room.
The exercise is one of many in their regimen. Sessions start with 200 jumping jacks. To toughen them, the students are pummeled in the stomach with an 11-pound leather medicine ball.
In the midst of the class, one waist-high girl in pink sneakers jabs and lunges with zest. The youngest member of the class, Miriam Baltimore, 10, said she enrolled "because it's fun," and because her brother, Joseph, 14, is there.
More typical is Tyrone Davis, an accounting major at George Washington University who said he's taking kickboxing for self-defense. The 18-year-old said it has already helped him fend off assailants who were trying to steal his new car outside the recreation center one night.
Taylor's kickboxers compete eight to 12 times a year at tournaments around the country. The next is in Akron, Ohio, on Aug. 24. The matches are similar to standard boxing matches.
They're held in regulation rings staffed by referees, trainers and a doctor. Fighters are categorized in weight classes. Boxers wear gloves and, if they choose, foot wrappings.
Three rounds are standard, each three minutes of lightning-fast kicks and punches, using elbows and knees to block the punishing blows. A critic once described them as "beautifully brutal." As tough as it looks, American-style kickboxing is mild compared to the way it's done in Myanmar and Thailand.
One Burmese style allows bare-fisted fighters to land punches, kicks, knees and elbows anywhere on an opponent's body.
To win, boxers must achieve "a knockout, a disabling injury, a submission or uncontrolled bleeding," according to a 1986 issue of Inside Kung Fu magazine.
But kickboxing is more than kicks and punches. Like kung fu, it has its own philosophy, espousing such values as self-discipline and personal courage.
"It's not what you call a dumb jock art," says Lon Walls, a two-time light heavyweight champion in Wheaton. "There's a unification of mind and body there . . . . The bottom line for me has been the discipline," he said.
As classes end, Taylor jokes with his students, reminding them of practice times. The discipline kickboxing demands has given many of his youths a maturity and self-control their peers lack, he said.
Many of his 70 students have gone or are headed to college, no small achievement in light of the grim statistics for inner-city youths.
Taylor and Bryant said they try to help their charges with personal problems, nag them when their grades are bad, take them out to movies and other activities. "I'm almost part of their families," Taylor said.