From club runners to Olympians, every athlete has a limit. Scientifically, this limit is defined as the body’s lactate threshold and when you exercise beyond it, running rapidly becomes unpleasant.
Years of training will improve both your enzymes and mitochondria and so improve your clearance, but there is a limit to how much you can improve your lactate threshold by training alone. If you inherit these enzymes and a larger mass of mitochondria genetically, your personal limits will be far higher.
For Dean Karnazes, ultrarunner from California, it seems as if he can run forever.
Read the full, original story here: Dean Karnazes: the man who can run for ever
