Marathon running also has the potential to increase life span and to increase the quality of that life span. Again, it’s not so much the running of the race that affects your health but the lifestyle changes that often accompany the commitment to run the race. To become a successful runner/marathoner, you need to (1) follow a proper diet, (2) eliminate extra body fat, (3) refrain from smoking and avoid heavy drinking, (4) get adequate amounts of sleep and (5) exercise regularly.

It was T. J. Bassler, M. D., a pathologist a Centinella Valley Community Hospital in California and one of the founders of the American Joggers Association who proposed the theory that if you could train for and complete a marathon, you would become immune to death by heart attack for at least six months. He later extended that immunity to a year – then beyond a year.

Over a period of year, eminent cardiologists attempted to dispute Dr. Bassler’s theory. They would cite evidence of a runner dead of a heart attack, and Dr. Bassler would point out that the runner didn’t run marathons. They would cite a marathoner collapsing in the last mile, and Dr. Bassler would note that the runner didn’t finish the race. Dr. Bassler refused to accept anecdotal evidence of coronary deaths, demanding to see x-rays. In several apparent marathon coronary deaths, he identified the culprit as dehydration or a cardiac arrhythmia rather than the standard heart attack caused by blocked arteries.

/Hall Higdon on Marathon