Schools must do more to ensure teen sporting stars do not neglect their education, Rugby Players' Association chief executive Rob Nichol says.
Secondary school principals say they are worried the intense competition between schools is prompting them to put a lot of pressure on their students.
Mr Nichol told Nine to Noon students were specialising in sport too early.
"Kids are giving up other sports that they enjoy to specialise in a particular sport and effectively put all their eggs in one basket only to find out four to five years later that actually there's not much at the end of the road for them," he said.
"As a result, they've compromised another area, and the biggest area we are frankly concerned about is education."
Parents and teachers needed to step up and act in teenagers' best interests, Mr Nichol said.
His concerns were backed up by sports researcher Craig Harrison, who said some school sports stars were being harmed by excessive training.
"We're getting athletes that are demanded to attend a number of practices a week," the AUT researcher told Nine to Noon.
"They're having to go to these games and they're just not ready to cope, both emotionally and physically.
"So we're ending up with athletes that are burning out and they're experiencing injuries that a lot of the time are putting them on the sideline for extended periods of time."
Students who specialised early in a particular sport often lost motivation, suffered from stress and sometimes dropped out of sport altogether, Mr Harrison said.
Auckland Grammar principal Tim O'Connor said there was also an issue with students being treated as elite sports people.
"I think we do really have to remember that we are involved with amateur sport and we should be trying to develop cultures that endorse our school culture," he said.
Macleans College principal Byron Bentley said the integrity rules needed more teeth, with tougher penalties for such things as poaching good players from other schools.
"Keep the focus on the main aim, which is to give them a good education and send them out with a qualification," he said.
"That's got to be the bottom line."