Mark Verstegen, the world-renowned performance coach who was at the forefront of the core training revolution, now applies his cutting-edge training system to the special needs of the endurance athlete.     Verstegen’s first two books—Core Performance and Core Performance Essentials—broke new ground in fitness with their intense focus on the muscles of the core: shoulders, hips, and midsection. That focus remains the key here as he not only helps endurance athletes train more effectively, but also gives them a potent regimen of core training that will help them move more efficiently, speed recovery, and stave off overuse injuries and long-term deterioration.      His plan:-helps endurance athletes at all levels—from competitive swimmers and hard-driven triathletes toeveryday joggers-delivers the desired combination of strength and stamina, balance and flexibility, athleticquickness and power—to which the endurance athlete strives-provides an endurance-oriented nutrition program complete with recommendations forpre- and post-race eating