Pre-workout weight: 155 pounds.
Workout: A 123-mile ride followed by a 60-minute run at Ironman race pace.
Gear: A fully vented road helmet.
Hydration strategy: Alexander had access to all the nutrition and hydration he wanted, but he was never reminded to drink.
Initial temperature: Once Alexander warmed up, his body temperature was 100.7 degrees, give or take 0.07 degrees.
Weight loss: Alexander lost approximately 4.9 percent of his body mass—7.6 pounds—during the brick workout.
Analysis: Despite the vented helmet and constant access to water and a sports drink, Alexander sweat out 7.6 pounds of water during the brick workout—equal to 4.9 percent of his body mass—which is more than twice the amount it takes to “impair aerobic performance,” the study said. Interestingly, despite the weight loss and the rise in temperature, Alexander still felt fine during his workouts. Steinmetz believes—based on the scientific literature—that if Alexander were to continue on to a complete Ironman distance, his temperature would continue to rise and his performance would suffer.