Excitement suddenly turned to fear for the 49ers youth football team as players ran off the field holding their stomachs and began vomiting violently on the sidelines.

Parents and coaches helped the eight boys, aged between 12 and 14, into cars and headed to the hospital, ending the practice for a championship game a few days later.

No one knew it at the time, but the sick 49ers had been poisoned, casualties in an epidemic of parental rage sweeping through youth sports.

Coaches are being threatened, referees assaulted and kids hurt more than ever by the parents of some of the estimated 30 million young players in organized sports.

From parents brawling at a T-ball game in Florida while four- and five-year-old children watched to a father being beaten to death at a hockey game in Massachusetts, anger is growing.

Leagues are responding by banning rowdy parents from the stands, holding silent games and trying to teach coaches and parents how to behave.

When that fails, authorities are putting the worst offenders in jail.

"From road rage to airplane rage to cell phone rage, children in sports aren't immune to all of this," said Fred Engh, head of the National Alliance for Youth Sports. "Now we have sideline rage."

Violence against umpires and referees has prompted many American states to get tougher. The Illinois Legislature recently passed a bill mandating penalties for people who assault sports officials, while 15 other states have similar laws.

Experts from across the U.S. will meet in Chicago next weekend for a summit on how to control violence in youth sports. They hope to create guidelines for parents.

In the meantime, the number of cases continues to rise.

"It's a reflection of when the parents grew up in recent years with violence in their childhood being the norm," said Richard Lapchick, who runs Northeastern University's Center for the Study of Sports and Society. "It would be unrealistic to think all of them have matured enough so that this violence didn't carry over."

Bad calls can lead to attacks and near riots. Sometimes, though, parents become dangerous by using misguided logic to try to help their children.

For example:

-- In San Fernando, Calif., a father was sentenced last year to 45 days in jail for beating and berating a coach who took his 11-year-old son out of a baseball game.

"How dare you make my son a three-inning player," the parent said before slamming the coach against a car, according to police.

-- In Albuquerque, N.M. in 1996 a dentist sharpened the face guard of his son's football helmet so he could slash opposing players. Five players and a referee were hurt and the father was sentenced to two days in jail and community service.

-- A police officer in Pennsylvania was convicted last year of giving a pitcher two dollars to hit a fellow 10-year-old Little Leaguer with a fastball during a game. The man, not related to players on either team, was sentenced to up to 23 months in jail for corruption of minors and solicitation to commit simple assault.

-- A parent in Reading, Mass., was beaten to death while supervising his son's pickup hockey game last July. Authorities say another father, Thomas Junta, became upset at rough play and fought with Michael Costin, a single father of four. Junta is charged with manslaughter and awaits trial.

"At what point did sports become not just for the kids and fun?" said Marshall Mathews, a parent and assistant coach on the 49ers youth football team in Las Vegas.

"All my years in sports my parents cheered me. No one could have imagined doing something like this," he added, referring to the poisoning of the eight players on the 49ers.

Parent Jerome Breland made them sick while trying to get back at a player who picked on his 12-year-old son. Breland put Ipecac, an herbal extract that induces vomiting, into his son's juice and told him to have the teammate drink it during practice.

The team didn't have enough water, however, and other players ended up drinking the juice. Breland was given six months' house arrest and ordered to perform a year of community service.

One of the sickened players, Stephen Boggione, was so traumatized he doesn't want to play sports anymore. On the way to sign up for baseball practice this spring, he began crying because he was afraid he would have to drink the water.

Lincoln Coverdale, a 17-year-old high school senior in Shaker Heights, Ohio, has played organized hockey for much of his life and knew many parents who put too much pressure on their children.

"The kid just has to sit there and be mortified because all the people around him are watching him get yelled at by his parents," he said.

Overbearing parents are also getting to referees, according to a recent survey by the National Association of Sports Officials. Seventy-six percent of respondents from 60 high school athletic associations said increased spectator interference is causing many officials to quit.

The organization keeps a list of attacks, such as when the coach of a Nebraska peewee flag football team punched a 16-year-old referee during a game and a fan in Ohio threatened a soccer referee with a gun.

"It's not worth risking your life for $50 a game," said Bob Still, who works as a high school baseball umpire in Wisconsin. "What we're concerned about is the tone and tenor have changed.

"Now they come at you with a bat in hand and a real intent to hurt."

In rare cases, stressed-out referees fight back. In Atlanta earlier this year a youth basketball referee slashed a coach with a knife, later telling police he was berated throughout the game and that the coach tried to choke him. In Jackson, Miss., last year an umpire in a men's league game stabbed a fan who had been shouting at him.

"The parent of today is much different than the parent of five years ago," said Engh, whose West Palm Beach, Fla.-based association has 2,200 chapters across the U.S. "It used to be maybe five per cent of the people stepped over the line.

"It's grown now to about 15 per cent."

His group has expanded its focus from training coaches and league officials to training parents.

In Jupiter, Fla., about 2,000 parents showed up earlier this year at a spring-training facility to listen for an hour on how to behave at games. In order for their children to play in the league, parents also had to sign a pledge they would support their kids and not cause problems on the field.

The program is being expanded to about 250 other leagues and Engh hopes to institute it across the U.S.

The National Alliance for Youth Sports is not alone in trying to keep parents and coaches under control.

In California, the Positive Coaching Alliance holds workshops for coaches to stress that being a positive role model is more important than winning. And Olympic gold medallist Marion Jones is the spokesman for Time Out for Better Sports for Kids, which runs a program to teach parents and coaches how to behave.

In El Paso, Tex., city officials initiated a program where more than 800 parents went to mandatory sportsmanship training last year. In Scarsdale, N.Y., the village's board of trustees last month banned booing, taunts and other verbal attacks at games.

Individual leagues have also taken action. The Northern Ohio Girls Soccer League began a Silent Sunday two years ago that forced parents to keep their cheers and criticisms to themselves one game a season.

It was eerily quiet, but effective.

"It was the greatest time-out in American sports," Engh said.

By Tim Dahlberg