Satellite cells are immature cells that surround muscle tissue. When muscle tissue is broken down during weight training, a cascade of biochemical and hormonal reactions can happen to send a message to a satellite cell to fuse to the damaged muscle tissue. In doing so, the muscle tissue gains the nuclei from the satellite cell, which aids in repair and growth. Nuclei are the brain centers of the cell and are responsible for signaling protein synthesis (new muscle). Danish researchers found that 16 weeks of creatine supplementation along with heavy-resistance training not only increases the number of satellite cells, but also the number nuclei in the muscle.

J Physiol. 2006 Jun 1; 573(Pt 2):525-34.