It's not uncommon in the NBA to see a guy scream after dunking and trot down the court wearing a scowl. The harder the dunk, the louder the scream, the more serious the scowl.

Most chalk this up to showmanship. But there's a reason many overlook. These guys are in pain.

"As a lot of times, you go up to dunk and you feel like you want to break that backboard, break that rim," said Golden State Warriors guard Jason Richardson, who with Michael Jordan is the only player to win consecutive slam dunk titles during NBA All-Star weekend. "But 10 times out of 10 you're not. What you're really breaking is yourself. . . . When you dunk it hard and come down screaming 'Ahhhhh,' everybody gets into it. But you're really screaming, "Ahhhhh, my arm!' "

Dunking is painful. There is a consequence for slamming one's hands, wrists and forearms against the rim. Falling from the sky takes its toll on the knees, endangers the ankles. That's not to mention the vulnerability of just being up so high.

But, obviously, such isn't a deterrent. The reward is greater than the risk.

"I guess the fame of the dunk is greater than the pain," Basketball Hall of Famer George Gervin said. "I was a dunker, so I know if you constantly do it, sooner or later it's going to put that bruise at the bottom part of your wrist. So they need to learn to develop that finger roll. I got tired of dunking, so I started rolling."

Chances are players won't be trading in the eminence of the dunk for the finesse of the finger roll anytime soon. Dunks are a staple of the modern game, basketball's home runs.

To today's players, dunking is more an art form and a means of self-expression than a way of assuring the ball gets in the basket. It's no longer that they dunked but how high they got up, how hard they threw it down and how the highlight looks on "SportsCenter."

But dunks come with a price. Sure, they provide momentum, captivate fans and make players millions of dollars. But ask any NBA dunker and he'll give you one of a million stories about the downside. He can tell you about a time he suffered for the splendor.

Los Angeles Lakers guard Kobe Bryant said he used to bust up his fingers until they bled. New Jersey Nets guard Vince Carter showed off the marks on his right forearm, which he stuck inside the basket during his famous jam from the 2000 dunk contest.

"I dunk so hard sometimes," Minnesota Timberwolves forward Kevin Garnett said, "I can't feel my hand for a couple plays."

"One time," Miami Heat guard Dwyane Wade said, "it hurt so bad I couldn't pick up a ball. You can mess yourself up dunking so hard."

The negative aspects of dunking do wear down players. Jordan, who took what Julius Erving popularized and turned it into a phenomenon, cut back on dunking because of his knees. A couple years ago while still with the Toronto Raptors, Carter vowed to stop dunking, but he hasn't kept that promise.

"Every now and then, I get a little too excited and mess up my forearm," Carter said. "That's what helped me get up higher, so I could throw it through (from above the rim) and not have to hit the rim."

Today's technology lessens the rigors of dunking. The hardwood is raised above the floor so the court has room to give, making it a much softer landing pad and taking some of the pressure off players' knees and ankles. The NBA also uses breakaway rims, which have springs and are designed to release when pulled down.

Of course, NBA arenas are a world away from the low-budget courts many NBA players came up dunking on. The nation's inner cities are filled with dangerous courts — unforgiving two-ply rims, sporting chains as nets, connected to a steel backboard by bolts, held up by an aluminum pole and planted into a concrete court covered with gravel.

"Now we're playing in plush gyms on breakaway rims," Bryant said. "It wasn't always like that. We used to play on some beat-up courts. . . . And we loved it."

Imagine way back in the day, in Gervin's time of the mid-1970s to mid-'80s. Even the NBA arenas had playing surfaces that were little more than kitchen floors, and dunkers took off and landed on canvas-and-rubber Chuck Taylor's.

"We didn't have the technology," Gervin said. "Most of the floors were (laid) on cement and didn't have any give. So technology and shoes and all that kind of play a major role in helping you prevent injuries."

Today's players certainly need the benefit of technology. They assault the rims with more aggressiveness and power than ever before, despite the consequences. And make no mistake, there are consequences.

Take Richardson. He said he was intent on making a name for himself in his first slam dunk competition. He did, too, awing fans with his combination of height and power to win the 2002 title. It wasn't without pain.

"Banging against that iron," he said, "I literally had to wear a pad on my forearm for two weeks."