THEY CLUSTER at the end of the first row of bleachers, waiting patiently with autograph books in hand, earnest young boys of various sizes who don't smile much. Hero worship is serious business. And the men about to appear from the locker rooms -- swathed in padding and gloves and helmets -- are serious heroes.

It's practice time for the Washington Caps -- battling for the lead in the National Hockey League's Patrick Division -- and the free show's about to begin at the Mount Vernon Sports Complex ice arena.

Scattered about the seven rows of bleachers in the chilly arena are hockey parents, hands cupped around 55-cent containers of coffee or cocoa. And behind the knot of boys are two young teen-age girls, waiting eagerly in their Caps jerseys emblazoned with the name of Scott Stevens, one of four Caps all-stars.

Fo the girls, there will be disappointment this day: As the players file onto the ice, they learn that their idol will miss their display of affection. Stevens and three other Caps -- Bob Carpenter, Rod Langway and Mike Gartner -- are away for the all-star game. But the boys fare better, getting the autographs of players like winger Gaetan Duschene and goaltenders Pat Riggin and Bob Mason before they get down to business.

Some of the Caps begin by stretching, like dancers at the barre, resting a skate on the barrier. Then, wearing the burgundy, green, gray or red shirts of their assigned line, they begin to glide around the rink. At the instruction of Coach Bryan Murray, stationed in the middle of the ice, they pick up the pace, then pair off to charge the goaltenders, encased in pads and shin guards and face masks.

The ice sprays from their blades as they make their rushes, their intensity beginning to show. The kids soak it up. They know these men -- their records, their injuries, possibly even their shoe sizes -- the way their grandfathers knew baseball and their fathers know football. They intend to be there some day. American interest in ice hockey has grown ever since a young American team won the gold medal in the 1980 Olympics. Currently the United States fields a national team, made up mainly of college-level amateurs and some pros, and a junior national team of high school age. Youthful players who gather to watch Caps practices may hope eventually to make those squads. And they are already sharpening their skating in international play. Last month, youth teams from the Washington area played in Quebec City, and in April, four more teams will journey to Helsinki and Leningrad to compete with youngsters where ice hockey is king.

The youngsters, of course, are heavily dependent on parent/coaches who are willing to cart them to practices and games in the dark morning hours of winter -- often the only time the rinks can rent them the ice time -- and to drive long distances to meet the opposition. Virginia teams from Mount Vernon and from Fairfax Ice Arena, for example, play other Beltway-area teams but also travel as far north as York, Pennsylvania, during the season.

Through it all, the game's the thing. And so it is that on some weekend mornings, after their own practices or games, the kids hang around to watch players at the pinnacle of the sport they love. Sometimes as many as 150 spectators watch weekend practices; the number falls to about 30 fans for weekday practices, according to estimates by staffers at the Mount Vernon arena. Much of the time, the boys just stand and peer through the rink's plexiglass shield, grinning when a player purposely whacks the side of the barrier with his stick, as much as to say, "Hey, I know you're there, kid."

Sometimes, if luck is with them, they get a prized trophy, a hockey stick nicked and splintered from the fray. It may not be good enough for a game, but it's just fine for use in scrappy street hockey or as a wall decoration above a young guy's bed where he can sleep, perchance to dream.

CAPITAL VENTURE -- You can see the Washington Capitals practice for free at the Mount Vernon Recreation Complex in Alexandria. Weekend practices are scheduled this Friday from 1 to 2 p.m.; Sunday, 11:30 a.m. to 1 p.m.; Saturday, March 23, 10:30 to noon, and Sunday, March 31, 11 a.m. to 12:30 p.m.

This month's weekday practices, which normally start at 10:30 or 11 a.m.: Monday; Wednesday; Monday, March 11; Tuesday, March 12; Wednesday, March 13; Friday, March 15; Wednesday, March 20; Tuesday, March 26; Friday, March 29.

GETTING THERE -- Take Capital Beltway Exit 1-A (Route 1 South), then bear right onto Fort Hunt Road. The road makes an immediate and abrupt left, crossing Route 1. Continue on Fort Hunt Road 11/2 miles to Belleview Boulevard and the sports complex. Call 768-3223 for recorded information, including fees and times for public skating and the daily Caps' practice times, and 768-3225 for further information.