Spine locks·Lumbar spine and knees · Gi & no-gi
Boston Crab.
Spine lock via leg control hyperextending lumbar region
Risk level
Low
lumbar spine and knees
Tap urgency
Gradual
tap response
Difficulty
2
/ 5 — setup
Danger level
6
/ 10
Positions
2
entry points
Perm. damage
Yes
irreversible risk
What it is
Spine lock via leg control hyperextending lumbar region
What you do
The step-by-step execution breakdown lives in the app — mechanics, tips, and the full entry sequence.
Open1submission detailin the App Store↗Setup complexity
2/10
Learning priority
3/10
Escapability
6/10
Versatility
2/10
Danger level
6/10
01
Tap immediately when feeling lower back or knee pressure.
02
Never attempt to roll or twist while caught—severe spinal injury risk.
03
Back flexibility varies dramatically between individuals; assess before drilling.
04
Avoid completely if you have herniated discs or spinal history.
05
Use minimal pressure in training; focus on positioning only.
WHITE — LEGALBLUE — LEGALPURPLE — LEGALBROWN — LEGALBLACK — LEGAL
2 ways in.
All2entriesin the App Store↗// Boston Crab · Spine locks
Drill it.
Log it. Track the tap rate.
Open Boston Crab in Grapla to add it to your drilling queue, log every attempt, and watch your finish rate move over the next 30 days.
Download on the
App Store