The problem with forcing a stretch
Chances are you treat stretching like a test: how deep can I get into something? It's a natural instinct. And BJJ rewards range of motion, so anything that promises "flexibility" gets filtered through a competitive lens.
When you force a muscle past the point of comfort, you're not making progress; you're fighting the system that's protecting your joints. Muscles that get pushed past their tolerance don't just pull tighter; they clamp down and guard. Anyone who's tried to muscle their way into a deeper butterfly stretch and felt their hips fight back knows this feeling.
This is important, because a lot of BJJ mobility (hip internal/external rotation, spinal flexion, ankle mobility, etc.) lives in ranges your nervous system doesn't fully trust yet, and forcing those ranges open with brute stretching doesn't build usable mobility; it just teaches your body to resist you harder next time. This is why so many grapplers stretch for months without their mobility actually improving.
Where breath comes in
The actual mechanism is built around breath, not depth. When you breathe through a position instead of muscling into it, your body starts recruiting other stabilizing muscles to hold you up. That lets the muscle you're trying to lengthen back off slightly, because it's no longer the only thing keeping you upright.
You're not fighting your own body for the position; you're finding the structure that lets you relax into it, and breath is what tells your nervous system it's safe to release.
Find the edge: move into the position until you feel the muscle's real limit, not pain, just resistance.
Breathe: slow, steady breath through the position. Don't hold your breath.
Let other muscles re-stabilize: as you breathe, your body will start supporting the position differently.
Let the range open gradually: once the target muscle backs off, you'll often find a little more room appears on its own.
The goal isn't a deeper split by tomorrow. It's building ranges of motion your body actually trusts under live pressure, which is the only kind of mobility that transfers to the mats.