Brain injury association Headway has expressed concern about Premiership Rugby's proposed fixture schedule for the remainder of the season, claiming it could result in an increase in players suffering concussions.
The Gallagher Premiership will resume on August 14 when Harlequins host Sale at the Twickenham Stoop.
It will end the competition's 159-day hiatus as a result of the coronavirus pandemic, and clubs will play midweek matches in order to conclude the 2019-20 season by October 24 – the date of the play-off final.
There will be just 10 weeks between rugby's resumption and the winner of the Premiership being confirmed.
During that gruelling period nine rounds of league fixtures need to be played, in addition to the play-offs plus the latter stages of the Heineken Champions Cup and Challenge Cup.
Headway's deputy chief executive Luke Griggs said in a statement to the PA news agency: "There does appear to be a risk that requiring teams to play games in such quick succession could lead to an increase in the number of concussions sustained by players.
"The longer the brain has to recover from any kind of impact, regardless of whether concussion was diagnosed, the less likelihood of a compounding effect from subsequent blows."
Griggs also pointed out the risk of head injuries can become greater when players are tired.
He added: "The increased physical demand on players will inevitably lead to an increase in fatigue.
"This in turn will make players more likely to make a mistake, such as getting into a poor position to make a tackle, which is a specific risk area for concussions."
The PA news agency has contacted Premiership Rugby for a response.
When Premiership Rugby confirmed its plans for the rest of the campaign on Friday, its rugby director Phil Winstanley revealed the organisation was in talks with the Rugby Football Union and Rugby Players' Association over player welfare.
He insisted a solution between the trio would be found to ensure the protection of players.
"It is incumbent on everyone in the game to make sure we manage players appropriately," Winstanley said.
"We will continue to work as three organisations and be collaborative in that sense and come up with a solution because it is in everyone's interest to have a fit playing group."
Clubs can play academy players in some games, with Premiership Rugby not intending to punish teams for fielding weakened sides.
Winstanley added: "We have to protect some player welfare. We need to leave that flexibility to directors of rugby to select the right team for the right game."
November 21 has been mooted as the start date for next season, which would give players just four weeks off.
But Premiership Rugby chief executive Darren Childs has insisted all 12 clubs understand and support the schedule.
He said: "We all acknowledge this is an exceptional year and we have had to make decisions that in normal circumstances would be difficult to make, but we are doing it for the right reasons.
"The clubs and everyone else agree with that. We have to move on, manage it carefully and... there are detailed conversations going on right now to make sure we protect those players for the long-term future of their careers."
