Cattermole - a £6m signing from Wigan in summer 2009 - says the squad are better for their German experience after they drew 0-0 with Borussia Monchengladbach.
"We are happy with the time we've been away," Cattermole told safc.com. "We've only had one day off and have been doing double sessions most days.
"The games have been tough and we went into today's game on empty really, but it's all in the bag now and we will go forward fitter and stronger.
"The lads have all played the same sort of minutes each and to get a clean sheet today was encouraging.
"We've still got three weeks until the start of the season. It's a different style of football over here which made it harder for us to press."