A new scientific study at the Ottawa Hospital Research Institute and University of Ottawa has revealed the answer: as people age, the stem cells in their bodies decrease in number.* Therefore, the ability for the body to repair muscle damage also decreases because the reservoir of muscle precursor cells available to differentiate into muscle cells has gradually been dropping. What causes this reservoir of stem cells to decrease?
According to the researchers who conducted this study, there is a signaling pathway from tissue that surrounds the stem cells which acts like a taxi dispatcher. A taxi dispatcher determines whether a particular taxi cab should go to the north or the south for its next passenger. In this case, the tissue, or our taxi dispatcher, emits a molecule that tells the cell to stop dividing into one new satellite stem cell and one new muscle cell but rather to divide only into cells that can become muscle fiber. Over time, this decrease in the stem cell population means that there will be a reduced capacity to repair and rebuild muscle tissue.