Andre Schurrle believes that Chelsea's training methods have contributed to his failure to gain maximum fitness in Germany.
The World Cup winner signed for Wolfsburg from the Premier League club in January for a reported £27m fee, but he has struggled to make a significant impact.
"At top English clubs during the season, the players are hardly loaded with any training, since it's almost all about regeneration and tactics," the London Evening Standard quotes Schurrle as saying.
"In England you can get your fitness through the season with the games. I'm still missing the last per cent. In January, I almost had no training between the change of clubs because of back problems."
Wolfsburg are currently second in the Bundesliga table, 11 points behind leaders Bayern Munich.