Your hamstrings aren’t tight. Your deep hip rotators lost control of the femur and now your knees pay for it. Stretching more won’t fix you if your muscles can’t control the range you already have. Flexibility and mobility get used interchangeably, but they are fundamentally different. Flexibility is passive range. It’s how far a joint moves when an external force pushes it there. Mobility is active range. It’s how far a joint moves under your own muscular control, with stability through the entire path. The problem with chasing flexibility alone is that you create range your body can’t stabilize. Your hip flexors might stretch beautifully, but if your gluteus medius and deep hip rotators can’t hold the pelvis steady at that new range, the load transfers straight into your lumbar spine. Your hamstrings might test as loose, but without eccentric control from the posterior chain, your knee absorbs force it was never designed to handle. That’s how people who stretch every day still end u...