During high-intensity training, athletes require specific nutrients, including carbohydrates for energy, protein for muscle repair, and electrolytes for hydration. Carbohydrates should be prioritized before and after workouts to sustain glycogen levels. B vitamins also support energy metabolism, while minerals like magnesium and potassium help maintain muscle function. Antioxidants, such as vitamins C and E, play a role in reducing oxidative stress from intense exertion. Proper nutrient intake is critical for optimizing performance and recovery.