"A good friend of mine once finished a six-hour ride in the mountains on nothing but pure water. No gels, no energy drinks—just water. And he was not out on a Sunday ride—he was hammering, riding hard on the ascents and flying down the descents. Can you do that? Or are you already thinking of how many gels and bars you would need to drag along for the ride?

While research over the last 10 years has improved our understanding of fatigue and the interplay of metabolism, heat and fluids—as well as the role our brains play in all of this—there is still a general consensus that the size of our carbohydrate stores and the rate at which we can derive energy from fat play a significant role in endurance. And while most triathletes are well versed on the carbohydrate side of this equation—how to stock and replenish glycogen stores before, during and after workouts—few understand how to tap into their ability to use fat for fuel."