High-frequency, low-load blood flow-restricted resistance exercise is associated with a 70%–80% increase in satellite cell numbers in type I and II muscle fibers after the first training block in young adults, followed by a further increase to 80%–147% after the second training block.

When muscles are worked with light weights and restricted blood flow, the lack of oxygen and buildup of waste products trigger muscle cells to activate repair cells called satellite cells. These cells multiply, turn into building blocks, and fuse with muscle fibers to add new nuclei. More nuclei allow the muscle to make more proteins, leading to growth. A temporary breakdown of muscle fibers happens first due to stress signals, but once that passes, the added nuclei enable stronger, larger fibers to form over time.