From muscle fibers to mental grit, here’s the science behind why some bodies can endure ultramarathons, while others hit the wall far sooner.
Heritage Images via Getty Images
Ultramarathons sit at the far edge of what the human body can endure….

From muscle fibers to mental grit, here’s the science behind why some bodies can endure ultramarathons, while others hit the wall far sooner.
Heritage Images via Getty Images
Ultramarathons sit at the far edge of what the human body can endure….