BERLIN (Reuters) - Juergen Mennel's 50-year-old feet have a lot of kilometers in them -- the social worker from Heilbronn estimates he has run the equivalent of more than seven times around the world.
But Mennel, a spindly man with a receding hairline, does not plan to give his feet a break after having run what he estimates to be 300,000 km (186,000 miles) over the last four decades.
He wants to mark the 2,500-year anniversary of the ancient battle of Marathon in Greece to run 2,200 km from his home in Heilbronn to Athens this autumn.
"I saw that the 2,500th anniversary was coming up and thought it would be a great athletic challenge to run from Germany to Greece," said Mennel, who plans to cover the distance from southwest Germany to Greece in 27 days.
That's an average of two full marathons a day. Mennel said he wants to honor his mythical forefathers with his run and create awareness about the health benefits of regular exercise.
His is one of several athletic events marking this year's anniversary of the original marathon run, culminating in the 28th Athens Classic Marathon in October.
The myth of the marathon dates back to the Athenian soldier Pheidippides, who ran from the battlefield near Marathon to Athens in 490 B.C. carrying the news of a Greek victory over the Persians and who is said to have collapsed and died at the end of his effort.
Mennel has spent his life in long-distance running.
On the track since he was nine years old, he is a former member of the German ultramarathon national team that won silver at the World Championships over 100 km in 1990.
An exhausting daily training regimen has kept him fit enough to put his body through the stress of extreme running, Mennel says. For the last 15 years, he has started his day at 5:30 a.m. by running up to 20 km followed by a dozen more kilometers in the evening.
Even in his day job, Mennel exercises. As a social worker at a Protestant charity, he has spent over 20 years giving people with mental and physical disabilities occupational therapy -- unsurprisingly, by running with them.
Mennel's fitness is even more remarkable as he eschews modern techniques of performance and protein supplements.
"Oh dear, that powder-stuff, that's not sports anymore," he says. "My secret is that I remain relaxed. I eat meat for protein, and I even indulge in sweets."
Health experts say it is almost impossible to take in enough calories to sustain the body on a run this long. But Mennel is not worried, saying that he is used to the extreme situations he will face.
To ward off boredom, Mennel has chosen a path through stunning natural scenery. He especially looks forward to the stretch along the Adriatic Sea, where he can also give his body a chance to recover by diving into the Mediterranean.
Other stages, though, give him more cause for concern. Greek marathon runners have warned him about the dangers posed by stray dogs in the mountains of Albania and Montenegro.
He wants to use his run to spread the message that diseases of civilization such as diabetes and Alzheimer's can be prevented by exercise.
"My generation of over-50-year-olds gets sick all the time," Mennel said. "These absences can be really devastating to professional productivity and to whole careers, especially in a recession. So employees and companies should incorporate sports into everyday life at the workplace."
The awareness created is more important than the run itself, Mennel says. His itinerary includes panel discussions and meetings with health scientists, and he plans to present the scientific information gathered along the way in a ceremony in Athens upon his arrival.
Mennel is not considering hanging up his sneakers, either. After reaching Athens, he is planning to run to the World Health Organization in Geneva, Switzerland in 2011.
Does it take a certain level of insanity put his 50-year-old body through such a herculean ordeal?
"I don't think I'm necessarily crazy," Mennel says with a chuckle, "I'm just predestined to run."
Editing by Steve Addison