Under IBJJF rules, you cannot wear a cup. That doesn’t mean that you shouldn’t wear a cup in training, but most people don’t.
BJJ black belt Stephen Kesting of Grapplearts was asked by readers about how not to injure your balls when training Jiu-Jitsu:
“How do I do the armbar without crushing my balls in the process?”
Kesting answered:
Now you could wear a cup, but most intermediate and advanced players don’t do that unless they’re training for MMA.
Instead of wearing a cup you could just use an easy fix: all you have to do is tighten your armbar and adjust your position so that your hips are closer to his shoulder.
In the video below Rob Biernacki and I give some examples of how to set up the armbar safely and generally protect the groin in BJJ.
The first part of the video is dedicated to answering question about protecting the groin when your opponent is trying to pass your guard with a kneecut style guard pass.
Then, at about the 5:09 mark, we talk about protecting your balls specifically during the armbar.
In that second half of the video Rob also shows a sweet way to set up the S Mount Armbar, so check it out below…
