Peptides & Muscle Gain a medical perspective. Peptide therapy is increasingly being discussed in the context of muscle recovery, lean mass development, and injury rehabilitation. When used judiciously, case by case, and under BPC 157 Before and After: 1 Amazing Transformation BPC 157 + TB 500 Blend 5mg 5mg HGH Peptides Lab Factory Direct Have you used peptides? What are your thoughts? Let me know below Peptides are short chains of amino acids that play vital roles in cellular signaling and repair throughout the body.