The physiological process that occurs during muscle hypertrophy involves the repair and growth of muscle fibers after resistance training. When muscles are placed under stress, tiny tears occur, and the body reacts by repairing these tears. This process is facilitated by satellite cells, which multiply and fuse to existing muscle fibers, increasing their size and strength. Hormones like testosterone and growth hormone play crucial roles in this process as well. Adequate nutrition, particularly protein, is essential for muscle recovery and growth.