San Francisco - World rugby chiefs have warned that Sam Warburton's premature retirement from the sport is a "red flag" and say that players may need to adjust gruelling training regimes to protect their careers in future.
Former Wales and British Lions captain Warburton stunned rugby this week after hanging up his boots at the age of 29, citing an inability to recover from a litany of injuries that have blighted his career.
World Rugby vice-chairman Agustin Pichot said Warburton's retirement was a warning in an era when professional rugby has become increasingly demanding for elite athletes.
"The red flags are there - Sam is one red flag - there was a tweet I saw about the number of injuries he has had and it was frightening," Pichot told reporters in San Francisco at World Cup Sevens.
"He had an outstanding career, but a number of injuries. We have to take care of the future generations."
Pichot said World Rugby was in discussions with the International Rugby Players Association about setting guidelines which would limit the workloads of top-level players.
The former Argentina captain acknowledged, however, that achieving uniform rules would be complicated given the often conflicting demands on players of clubs and country.
"We are working towards a training-load system," Pichot said. "We have to learn how to integrate not only the unions but the clubs - don't forget that. You can tell a union that players should only train 10 hours a week - say - but maybe the coaches at the clubs train them more. The coaches and owners will want them to play every single week because they want to win to make money. It has to be addressed.
"First of all is the safety of the players. The players want to earn more money, so have to train more and play more."
Players also needed to negotiate safeguards into their contracts, Pichot said.
"We talked about it with the players last year - we said 'We want to take care of you, but let's be honest, when you sign a contract sometimes you don't protect yourself, and want to play week-in week-out'. There is a balance to be made."
World Rugby meanwhile has recently moved to address the issue of head injuries caused during tackles.
Current laws allow for tackles to be made at shoulder height, but World Rugby has trialled a new law which lowers the level of legal tackles to nipple height.
"There is a crucial thing coming, and a debate about where we are going with the physicality of the game and high tackles," Pichot said.
"When we played the game - when you had a knock on the head it was seen as brave to carry on playing. We can't do that anymore, the game has changed."
World Rugby chief executive Brett Gosper said no changes to the tackle law would be made before the 2019 World Cup in Japan, but hinted high tackles could be scrutinised more rigorously via the Television Match Official (TMO) system.
"There will be no law changes before the World Cup now, but there might be directive or protocol changes, for example regarding the use of the TMO," Gosper said.