Kathmandu, July 28 -- "Nepal, you do not want to lose these athletes."

This warning comes from Andy DuBois, one of the world's premier ultra-trail running coaches.

DuBois hails from Australia and is a former elite trail runner himself. He won the gruelling Hardmoors 110-mile (177-kilometre) ultramarathon in 2010, completing the distance in 22:38:00.

DuBois, however, isn't just an elite endurance coach. He is the world's go-to expert on using technology to measure a runner's true effort. Just as cyclists use power metres on their bikes, trail runners now use sensors to measure "power", or the exact amount of energy their muscles pump out in real time. When Stryd, the world's leading maker of these running devices, needs expert advice on...