Fifa said on Monday it is proposing five substitutions per match when football resumes, to help players cope with the increase in the number of games.
The world governing body has sent its proposal to the International Board (IFAB), the guardian of the laws of the game, which has to approve it before it can be implemented by national leagues.
"When the competition resumes, the calendars will be overloaded with a higher than usual number of matches," a Fifa spokesman said.
"The safety of the players is one of Fifa's priorities. One of the concerns is that the high frequency of matches may increase the potential risk of injuries."
To address these concerns, Fifa has made a proposal to the IFAB to "temporarily relax Law 3 of the game to allow for a greater number of substitutions. Each team could make five substitutions during regulation time plus a sixth substitution during overtime."
The proposal would need to be studied quickly by the IFAB as some leagues are planning to resume after stopping play because of the coronavirus pandemic in early May.
The measure could remain in force throughout the 2020-2021 season and also apply "in theory" during next summer's European championships, according to a source close to Fifa.
"If this measure is validated by the board, each league and each body will be able to decide whether or not to apply it and in the competitions of its choice," said the Fifa spokesman.
