In every basketball gymnasium and on every playground there’s one fundamental distance that denies no one — 15 feet of universal freedom. The concept of a free throw is a beautiful thing.

Not everyone can dunk a basketball, but everyone, from the guy at the local arcade Pop-a-Shot to the kid at the county fair, can shoot a free throw. And in a league where men insult gravity and unnatural athleticism abounds, a free throw is the National Basketball Association’s great everyman equalizer.

So if a free throw is so simple, then why do some of the world’s best athletes make it look so foul?

There’s no defender. It’s a stationary target. The distance never changes. Jumping isn’t involved. Noth-ing is clearer than the clarity of the charity. Sure, there’s noise and waving hands and wiggling balloons, but try telling that to the bolt riveter whose office is a two-foot-wide beam at the top of a skyscraper, or the guy investing retirement funds in the trading pit.

`NOBODY’S PERFECT’

Shaquille O’Neal, the Miami Heat’s center, is not a good free-throw shooter. He’s not even average and only slightly better than wretched. O’Neal shot 40.5 percent from the line in the Heat’s first-round playoff series against the Chicago Bulls, a series the Heat won 4-2.

O’Neal started strong from the line — 5 of 8 in Game 1 and 6 of 7 in Game 2 — but has since regressed to historic doldrums — even for O’Neal.

He missed seven consecutive free throws spanning two games and then went 2 of 12 in Game 5 and 4 of 8 in Game 6. That’s 40.5 percent for the Bulls series. Drop-kicking might be nearly as effective. He fared a little better Monday night in Game 1 versus the Nets, going 8 of 14.

O’Neal came to terms with his free-throw struggles long ago.

”Me having a beautiful wife and great family and friends . . . all the money I’ve got . . . a Ferrari . . . the rings I got, the two mansions on the water, a master’s in criminal justice, I’m a cop, plus I look good. So me shooting 40 percent at the foul line is just God’s way of saying nobody’s perfect. If I shoot 90 percent from the line, it just wouldn’t be right. I’d shoot zero percent before I’d shoot underhanded,” O’Neal said in the July 2005 issue of Esquire.

Hall of Famer Rick Barry shot free throws underhand. Barry, who played his college ball at the University of Miami, is the only person to lead the NCAA, the NBA and the American Basketball Association in scoring. He shot his free throws granny-style at a career clip of 89 percent.

”It seems rather ludicrous that people can’t shoot 80 percent,” Barry said. “You’re not a good free-throw shooter if you don’t shoot 80 percent. It’s the same ball, the same basket, the same distance. It’s ridiculous.”

Barry attacks the topic of free throws with the same aggressive flair that made him a Hall of Famer. He led the ABA in free-throw percentage three out of the four years he played in the league. He was the NBA’s most accurate free-throw shooter five times and ranks second on the NBA’s all-time free-throw percentage list (90 percent) behind Mark Price (90.4 percent). So, Barry knows his free throws.

”There’s no art to the free throw,” Barry said. “You’re just doing something fundamental. It’s a repetitive motion. The astonishing thing to me is to see these people who don’t have a routine.”

Barry’s underhand routine: “Three bounces, hands on the ball at the same time, relax and take a breath and shoot the shot. Every time. It enables you to not think about winning or losing the game. The focus is on the routine and not the enormity of the situation.”

If there is an art to the free throw — Barry said there isn’t, but then proceeded to describe a Rembrandt — then O’Neal expresses himself with a child’s broken crayons: colorful, erratic and outside the lines.

O’Neal is a future Hall of Famer. He has won three NBA championships and is striving for a fourth. He is an unstoppable force and an athletic icon unparalleled in all of sports. He knows this. He calls himself ”Superman.” But even Superman has a weakness. Put O’Neal at the free-throw line and watch a seven-foot-one, 325-pound basketball superhero heave line-drive darts of kryptonite like a mere mortal.

`HACK-A-SHAQ’

Opponents can’t stop O’Neal, so they foul him with the sole purpose of sending him to the free-throw line. This strategy — ”Hack-a-Shaq” — is no secret. O’Neal’s career regular-season free-throw average stands at about 53 percent. Come playoff time, it’s even worse — 51 percent.

After the 2000 season, Barry approached O’Neal during the Summer Olympics with the hope of teaching O’Neal how to shoot underhand free throws.

”He was actually ready to do it . . . but the Lakers didn’t want to hire me at that time,” Barry said. “[O’Neal] could have been a definite go-to guy instead of a guy coaches take out because they don’t want people fouling him.”

Barry spoke with O’Neal again a few years later with the same proposal, but O’Neal declined.

”[O’Neal] said he was a hip-hop kind of guy and it wouldn’t be good for his image,” Barry said.

It’s no surprise that O’Neal balked on shooting free throws underhand. Barry, too, was skeptical of the idea when his father, Rick Barry Jr., first approached him with the idea. Rick Barry Jr. played semipro ball and shot his free throws underhand.

”He kept bugging me so I went out with him one day and did it, really, to get him off my back,” said Barry, who said he made the switch in high school. ‘But I said, `This is pretty good.’ I kept working on it and wish I had made the changes earlier.”

Barry says Ben Wallace is another candidate for shooting free throws underhand.

Wallace, the All-Star center for the defending Eastern Conference champion Detroit Pistons, is one of the NBA’s most athletic players. He jumps high, runs fast and bulges with muscles. A four-time winner of the Defensive Player of the Year Award, Wallace is an intimidating presence under the basket, but at the free-throw line his athletic hands morph into a pair of skillets. He’s a career 42 percent shooter at the line.

AT A DISADVANTAGE

There has been supposition that taller players such as O’Neal and Wallace are at a free-throw disadvantage. Their height puts them closer than other players to the height of the basket and therefore they tend to not put enough arc on the ball.

Barry once helped a teammate, George Johnson of the Golden State Warriors, improve his free-throw percentage by nearly 20 percentage points by having him shoot underhand. ”That’s a pretty good indication that it works,” Barry said.

Dr. John F. Murray, a sports psychologist in Palm Beach County, makes a living out of helping professional athletes perform under intense pressure, and free throws offer that pressure.

”When you’re talking about performance failure, it often does fall into fear or the feeling of threat,” Murray said.

“Very few people can compete well in those situations. I say don’t create the fear yourself.”

It’s quite simple, really. Just always remember that somewhere in Freeport, Maine, there’s a lumpy couch potato sitting on the 100percent-free-throw-shooter side of the TV screen, screaming, “My grandmother can make a free throw.”

It’s a beautiful thing.