Whats the scientific basis for prioritizing protein intake on recovery days, and is it more effective to consume a specific type of protein, such as whey or casein, to optimize muscle repair and rebuilding, or is the timing and overall protein intake more important than the type of protein itself? Are there any studies that demonstrate a significant difference in recovery outcomes between cyclists who consume a high-protein diet on recovery days versus those who follow a more balanced macronutrient approach? Does the current emphasis on protein-heavy recovery diets overlook the importance of adequate carbohydrate and healthy fat intake for optimal recovery and performance?