Dylan Hartley is progressing well as he bids to be fit for the start of the new season at Saints.
The England captain suffered his latest head knock in the final match of the NatWest 6 Nations against Ireland in March and has not played since, as medics advised he take an extended break from the game.
While Hartley, who has not played for Saints since January, has passed all the return to play protocols for concussion, the time out of the game has left him deconditioned ahead of the new campaign and he has been placed on a modified fitness programme.
He played a full role in training at England’s camp in south west London on Saturday but the following day completed a strength and conditioning session while his team-mates were put through their paces by boss Eddie Jones.
Saints start their pre-season campaign at Ospreys on Saturday before further friendly matches against the Dragons and Glasgow Warriors.
Their first game of the new Gallagher Premiership season comes at Gloucester on Saturday, September 1.
And when asked if Hartley will be ready for that game, England forwards coach Steve Borthwick said: “That’s ongoing as he progresses through the process.
“The start of the season is a month away so he’s progressing. I think everything’s going well at this stage.
“For any player who has a good spell out of the game for whatever reason, there’s always a progression through the different aspects of the game to be physically prepared.
“He’s come into camp incredibly enthusiastic.
"He’s enjoying being here and it looks like he enjoys being back on a rugby field.”