Rather than studying for my looming finals, I've had a rather scintillating conversation about triangles from guard and the appropriate ways to defend them online. While this is an MMA site and my postings are purely in the context of BJJ, I see enough cross-over in this position to believe it may interest some of you guys as well.
As I transcribe some of my musings in a digestible format, I think it's fair to mention my credentials so you can take this technical post with the appropriate amount of salt. I have two years of very active experience in BJJ. I am currently a blue belt and placed silver at my most recent and only (no-gi) tournament at this rank with a record of 3-1 in December of 2012.
Variants of Triangles
Triangles come in two basic flavors, those where your opponent elects to create space between your hips and their own, but stays square with you, and those where your opponent angles off to the side (perhaps underhooking the leg or arm) while maintaining as little space as possible between your hips and their own. It's important to understand that this is a spectrum, not a rigid classification system.
Triangle Variant 1 via rhodymma.files.wordpress.com
Triangle Variant 2 via 2.bp.blogspot.com
My Top Triangle Defenses
In order to posture up out of a triangle, one should gable grip your your trapped and free hand at the hip of your opponent, then press downward on the hip attempting to glue it to the ground. Next, execute upward body posture, straightening your back, neck, and head from the hips up. This motion is essentially a dead lift. This vertical pressure induces your opponent to lengthen his legs thus opening the triangle.
Sometimes it may be possible to pass guard in order to escape the triangle. In order to execute this defense, arc the hip on the side of the trapped arm toward your opponent's hip. While doing so, slide your head down and out of the triangle and secure side control.
Defensive Decision Structure
There are two types of pressure you have to worry about in a triangle: downward and inward. Downward pressure helps your opponent maintain positional fortitude whereas inward pressure compromises your carotids.
It's important to note no matter which variant your opponent achieves, a capable opponent can control your posture and submit you, so don't disrespect either one. However, I find the greatest threat of the first variant to be downward pressure, whereas the greatest threat of the second variant is inward pressure. This is because in the first method, your opponent is far away from you so you have less leverage to generate upward pressure, however, you execute the choke with weak adductor muscles. Meanwhile in the second variant it is easier to generate leverage when posturing against an object so close to your base, but the second triangle uses the much stronger quad and hamstring muscles to execute the inward choking pressure.
The idea of "posturing up" is only possible if you feel you can dead lift your way out of your opponent's downward pressure. I often find this impossible in the first variant of the triangle because you're dead lifting an object that is very far away. In this sense, I may prefer to use the posturing method on a triangle in which my opponent is using the second variant of triangles, as the effectiveness/strength ratio goes up as distance decreases.
The guard pass method is not without disadvantages as well. It exposes you to a very obvious omoplata. You're essentially forcing them to go for the omoplata in order to defend your guard pass from the triangle. As long as you know this and are prepared to counter that submission, you can still benefit from this technique. Work a couple different omoplata escapes such as rolling through the omoplata or jumping through to the opposite side control in order to effectively try this method.
In addition to the counters available to the guard pass method, there are physical challenges to executing on it as well. As you arc your hip toward theirs, your arm becomes more firmly pressed to their leg. This is a dangerous pass to do if you already are wary of the inward pressure your opponent is applying to your carotids. You may end up choking yourself out. For this reason, this pass may synergize more effectively with the first variant of triangles than the
Similar to submission chaining, it can be fruitful to combing these two methods. Posture up to create space, then quickly hunker back down, arc your hip towards theirs, and try to slide your head out of the triangle and pass to side control. If you do this fast, you may be free of any submission chains because they were surprised by your misdirect.
Please notice my hesitancy to use affirmative language when I explain my thought process. What you really need is an ability to take a quick subconscious assessment of the downward and inward pressure, in addition to your arm position, which I have failed to talk about entirely, and then decide whether and how to defend against your opponent, or just tap and try it again next time.