Former Germany striker Stefan Kiessling admits his wife passed fitness tests on his behalf

Pre-season can be gruelling for professional footballers.

A time to improve fitness and sharpness for the new campaign, players' progress is monitored closely by their clubs - perhaps not closely enough, judging by Stefan Kiessling's recent admission. The 34-year-old called time on his playing days at the end of last season, bringing to a close his 12-year run at Bayer Leverkusen, where he now assists club sporting director, Rudi Völler. Looking back on his career in an interview with SportBild, Kiessling has revealed that he let his wife Norina do some of pre-season tests on his behalf. "I never did one hundred percent of the exercises in the preparation periods, not once," he explains. "You get a heart rate monitor on which all runs are saved. "As my wife is very athletic, she did some racing with the wristband according to my specs." "She did it so well that nobody noticed," he adds, before stressing that his wife helping him with his pre-season fitness data never had an impact on his performance on the field. Kiessling, who played six times for Germany during his playing career, started his career with FC Nürnberg before moving to Leverkusen in 2006. He scored 131 goals for the club in 342 games, establishing himself as a firm favourite with their supporters.