Teach me exactly step-by-step how muscle synthesis works, especially in the context of exercise

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Muscle protein synthesis, or MPS, is the fundamental process by which our muscles grow and repair themselves. Think of it as your body's construction crew, constantly building new muscle proteins from amino acid building blocks. This process is essential because muscles are in a constant state of breakdown and rebuilding. Exercise acts as a powerful trigger, significantly increasing the rate of muscle protein synthesis for up to 48 hours after your workout. Now let's explore the cellular machinery that makes muscle protein synthesis possible. Inside each muscle cell, we have several key players working together. Ribosomes act as protein factories, reading instructions and assembling proteins. The nucleus serves as the control center, housing DNA and producing messenger RNA instructions. Transfer RNA molecules transport amino acids to the ribosomes, while mitochondria provide the energy needed for this entire process. All of this happens in the sarcoplasm, the cytoplasm of muscle cells. The synthesis process follows three main steps. First, transcription occurs in the nucleus where DNA is copied into messenger RNA. This mRNA then travels to ribosomes in the cytoplasm. During translation, the ribosome reads the mRNA code while transfer RNA molecules bring specific amino acids. These amino acids are linked together in the exact sequence specified by the genetic code. Finally, the newly formed protein chain folds into its functional three-dimensional structure, creating muscle proteins like actin and myosin that enable muscle contraction. Exercise creates the perfect storm for muscle protein synthesis. When you lift weights or perform resistance training, mechanical stress causes microscopic damage to muscle fibers. This damage triggers cellular signaling pathways, particularly the mTOR pathway, which acts like a master switch for protein synthesis. The mTOR pathway dramatically increases the rate at which ribosomes produce new muscle proteins. Resistance training typically produces a stronger and longer-lasting synthesis response compared to endurance exercise. This elevated synthesis rate can persist for 24 to 48 hours after your workout, which is why proper recovery timing is crucial for muscle growth. Proper nutrition is the fuel that powers muscle protein synthesis. Dietary protein provides the essential amino acids needed as building blocks. Leucine, in particular, acts as a molecular trigger that activates the synthesis machinery. Complete proteins containing all essential amino acids are most effective. Timing is crucial - consuming protein within two hours post-exercise maximizes the synthesis response. The key to muscle growth lies in achieving a positive protein balance where synthesis exceeds breakdown. This requires the perfect combination of exercise stimulus, adequate protein intake, and sufficient rest for recovery.