L-Sit Chins are WAY harder than pullups. What is the reason?

Why are L-Sit Chin Ups so much harder than standard pullups? I was reading "The Naked Warrior" a book about the nature of how strength is recruited in the body. It uses the term "irradiation" to suggest that a nearby muscle contraction (tighter finger and wrist pressing during a pushup, for example) makes the larger muscle groups more effective in ways that isolating the primary muscle's contraction will not.

But in L-Sit Chin Ups, the opposite seems to be true. The contraction is somewhat more distant from the pulling motion. Does anyone know if there is a scientific name to the principle behind this? Why is the pulling seemingly weaker now?

When you are doing a pull-up without any bend in your waist, the weight of your legs is pulling at your shoulder joint straight down. When you do them in an L, the weight is in front of you, and that exerts extra force against your shoulder (forcing them more open) in order to compensate for the center of gravity being moved.

It definitely makes a big difference.

Thanks Jman! Not only do I understand the move, but I need to learn to open my shoulders better anyway. This is DEFINITELY something I'll want to keep working on.

Opening your shoulders during an L Chin?

There's no shoulder opening in the gymnastics sense, mr. havoc.

When you do a chin up with a flat body, you contract the biceps and lats (let's make it simple). There's a balance between bicep and lat in this sort of movement. Using only bicep will leave you doing a curl, using only the lats makes you do a row. The more weight directly under the bar, the more you use your biceps. The farther the balance point is in front of the bar, the more the lat is used. If you put weights on your feet during the L sit chin, you'll notice it's even harder than just the ab contraction.

That's why squats and front squats are separate exercises, even though the difference is less extreme