Saracens players involved in Saturday's Aviva Premiership victory over London Irish wore sensors designed to measure the force and direction of impacts to the head.
Wasps' recent improvement continued with a win over Gloucester while there were also post-Christmas Aviva Premiership wins for London Irish, Bath, Leicester, Saracens and Northampton.
Owen Farrell scored a try and kicked six points on his return to the Saracens side as they kept themselves in European Rugby Champions Cup contention with a 19-15 triumph over Sale Sharks.
England number eight Billy Vunipola has been replaced by Thomas Waldrom in the squad preparing for Saturday's QBE International against Australia because of concussion.
With Stuart Lancaster’s England squad now fully assembled at Pennyhill Park and preparing
themselves physically and mentally for their clash with New Zealand, two players who have been
drawing particular attention are the uncapped duo of George Kruis and Henry Slade.
Owen Farrell will make his first start for five weeks - and a fortnight before England face world champions New Zealand - when Saracens tackle European Champions Cup rivals Munster on Friday night.
European Champions Cup round 1 preview: Saracens boss Mark McCall says that despite his side reaching the final of the Heineken Cup last season, this year's Champions Cup campaign could be an even harder slog.
Saracens back-row forward Billy Vunipola says he is coming to terms with the "extra attention" he is receiving following his breakthrough season last year and that he just wants to keep improving.
After another thrilling weekend of rugby action from the domestic competitions in the northern hemisphere to the Rugby Championship in the south, the Pick of the Premiership is back once again.
The Premiership picks are coming through thick and fast and this week, week three of the feature, we at Talking Rugby Union wanted to bring you the best tries of the weekend.
Each week Talking Rugby Union are going to bring you short highlights of the most exciting plays, biggest hits and best tries from the Aviva Premiership.
After a fantastic summer of rugby that has included sevens at the Commonwealth Games, internationals in the southern hemisphere and the start of the Rugby Championship, domestic rugby has finally come back to English shores for the start of the Aviva Premiership.
Saracens will open their European Rugby Champions Cup campaign by renewing hostilities with Clermont Auvergne, the French side they trounced to reach last term's Heineken Cup final.