Low-load resistance training with blood flow restriction at 20%–30% of one-repetition maximum may induce hypertrophy of type I muscle fibers in athletic populations by triggering metabolic stress mechanisms, including lactate accumulation, cellular swelling, and activation of the GH/IGF-1/mTOR signaling pathway, providing a joint-sparing alternative to high-load resistance training for rehabilitation and in-season maintenance.

When a person lifts light weights with bands that block blood flow out of the muscle, waste products like lactic acid build up inside the muscle cells. This buildup tricks the nervous system into recruiting more muscle fibers, even though the weight is light. The accumulated chemicals also pull water into the cells, making them swell. This swelling and the presence of lactic acid turn on a key molecular switch called mTORC1, which tells the muscle to make more protein and grow, especially in the endurance-type fibers.