Blockers can be most effective when they work together.
The London Rollergirls give us a tutorial on how to perform a successful Crabwall.
A Crabwall is a defensive wall formation, covering the track in order to stop the opposing team's Jammers from weaving through and scoring points.
There are three Blockers and a backwards-facing Blocker providing extra support and strength as the Jammer hits.
What are you waiting for? Get your skates on and take a look at our guide to Roller Derby.