Regular training and adequate nutrition are key factors in modulating exercise performance: Optimal performance requires a healthy diet adapted to the specific demands of the individual athlete's training and competition. Research has shown an impact of dietary intervention on the modulation of the skeletal muscle adaptive response to prolonged exercise training. Proper nutritional coaching should therefore not be restricted to the competitive events, but needs to be applied throughout both training and competition, each with its specific requirements regarding nutrient provision. Proper nutritional counseling will thus improve exercise training efficiency and ultimately increase performance capacity. Moreover, dietary counseling to modulate training efficiency is also relevant to the general public and the more frail clinically compromised patient groups. This book provides a solid scientific basis to help the reader define key targets for future interventions and develop new insights into the complex interaction between nutrition and exercise.