When your muscles swell up from the burn during a workout, that puffiness might trick your cells into thinking they’re being stretched, turning on growth signals — like a fake workout signal.

When your muscles swell up from fluid buildup during a tough workout, that pressure might send signals to your cells to grow bigger — even if you’re not lifting heavy weights.

Passive stretch acutely activates anabolic intracellular signaling pathways, including mTORC1 and MAPK, which regulate muscle protein synthesis and hypertrophy, as consistently demonstrated in rodent and in vitro muscle cell models. These mechanosensitive pathways convert mechanical tension into chemical signals that promote muscle growth, providing a biological foundation for stretch-based hypertrophy interventions.