Which nutrient is most closely associated with muscle repair and growth?

Proteins are essential for muscle repair and growth due to their role in providing the building blocks, known as amino acids, that are necessary for muscle tissue synthesis. When the body undergoes physical activity, especially strength training, muscle fibers experience micro-tears. Protein intake after such activity is crucial because it supports the body's repair processes by supplying the necessary components for the recovery and rebuilding of muscle fibers.

Furthermore, certain amino acids within proteins, particularly branched-chain amino acids like leucine, have been shown to stimulate muscle protein synthesis, making protein not just vital for repair but also for promoting overall muscle growth. While carbohydrates provide energy for workouts and fats are important for overall health and hormone production, neither serves the same direct role in muscle repair and growth that proteins do. Vitamins, while important for various bodily functions, do not provide the structural support needed for muscle tissue. Thus, proteins stand out as the nutrient most closely associated with muscle repair and growth.