I'm glad you liked it. Here's a snippet from "Triathlete" "Athletes in particular might find it easy to explain away fatigue or muscle cramps, lowered immunity, and even altered heart rates, and indeed these symptoms are common and multi-faceted in cause. However, a simple magnesium deficiency could also be the underlying factor. There is emerging evidence that magnesium requirements are significantly elevated in athletes, and that performance might benefit from higher intakes. Aside from being used up in the production of energy, magnesium might also assist performance by reducing accumulation of lactic acid and reducing the perception of fatigue during strenuous exercise through its action on the nervous system. Magnesium is also lost through sweat, so athletes training hard in hot and humid environments might further increase demands. Magnesium deficiency is actually quite common—dietary surveys indicate more than 70 percent of the population consumes insufficient magnesium. The recommended daily allowance for the general population is a minimum of 300 to 350 mg for women and 400 to 450 mg for men. Research suggests that endurance athletes can safely consume 500 to 800 mg daily, and there is debate as to whether this amount should be higher still."