German muscle man Gunter Schlierkamp flexed his biceps at Squats Gym in Mitcham Lane, Streatham, where he gave reporter Rachel Blundy some lessons in how to keep fit...

But the former Mr Olympia finalist, who is on a tour of the capital to promote the Multipower Professional protein supplement range, said he would only train the most dedicated of athletes.

He said: “I am not the kind of person that I want to force someone.

“It has to come from them.”

Weighing in at more than 300lbs, Mr Schlierkamp, 42, won his first major bodybuilding contest in 1990.

He has since claimed scores of titles for his strength and for his hefty physique.

Speaking to gym fanatics, he said the key to success was doing intense workouts on individual muscle groups, but admitted even he got tired of his high protein diet.

He said: “At the end [of my bodybuilding training], it was really hard to eat that much – I had to force it down.”