New measures have been introduced to ensure England and Premiership players are guaranteed rest time following the restructuring of rugby's calendar because of coronavirus.
England players will have a week off after Italy v England on 31 October.
After then playing in an eight-team international tournament, they will have two more weeks' rest in December.
Players' chief Damian Hopley said the schedule for the next 12 months will be "the most arduous ever undertaken".
The Rugby Players' Association chief executive added: "All stakeholders have worked collaboratively to agree essential player welfare initiatives in these extraordinary circumstances.
"We recognise the duty of care that the clubs and Rugby Football Union have for the players and we will all continue to work closely with the medical and strength and conditioning experts to monitor individual player load throughout the challenging schedule that lies ahead."
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Because of the Covid-19 pandemic, players will take part in more matches in a shorter space of time, with the Premiership featuring midweek games in order to finish the season after a five-month hiatus.
In 2021, the Premiership final will take place on 26 June, one week before the British and Irish Lions' first game in South Africa.
Under the new measures, no Premiership player can play more than 180 minutes across three matches in a week, nor can they start three games in a week.
Those who feature in the 2020 Premiership final on 24 October will get a two-and-a-half week break before preparations begin for the start of the 2020-21 season on 20 November.
Those playing for Saracens, Exeter and Northampton must also navigate the Champions Cup knock-out stages, which begin on 19 September.
Other welfare initiatives, which will be monitored weekly, include:
- Mental health monitoring for all players
- No player will start all three games in a week
- No player will be selected in more than six matches in the seven games between 14 August and 13 September
- A player's training load will be managed if they are selected in three match day squads in any given seven-day period
- No pre-season friendlies before the 2020-21 campaign for clubs in the Premiership or European finals
- The Premiership Rugby Shield will be cancelled for the 2020-21 season and will be reviewed