Scapula stabilisation during pullups.

I recently read somewhere that if your legs raise up during a pullup, you aren't stabilising at the scapula properly.  I always saw it as merely the extra involvement from the core necessary to complete the move.  I generally perform my pullups in the hollow body position (prevents swinging, activates core) but my legs do have a tendency to rise up, especially towards the end of a set.

So am I not stabilising at the scapula?

I think its more likely you are leaning back as you get tired.

it depends on what you need to do. if you want to perform a pull up as a movement to build up both strength and muscle with no goal for following progression you can do it by:

-start from hang position

-depress the scapula

-retract the scapula moving the chest forward and upward (strenum up)

-the body will naturally move backward

-think to pull the elbows down

this is from a weightlifting POV the best lats activation, the trajectory is more diagonal.

On the other side if you need to work to reach a solid foundation for future skill you need to pull vertical, in this way the biceps component is much more big then the previous version and you need to stay hollow. the scapula stabilization is due to depression that works against impingement , the hollow press the ribcage on the spine, while, the retraction isolates the lats.

i think that your trying to add some momentium to do a few more reps 

DiTi said:

i think that your trying to add some momentium to do a few more reps 

It's not a fast leg raise.

Just a thought to consider: If you don't want your legs to move at all. Do L-sit while you are doing your pull/chin ups. 

Squeeze your glutes whilst being in a hollow body. This way locks your body into place. I also do this for push-ups and PPP and my body is like a plank.

I've seen this before but I believe it has something more to do with putting your weight forward so the retractors/depressors can relax (they're exhausted) and this engages the teres major and lats much more. Sometimes I see the raised legs paired with a protracted scapula. 

Just my view on the situation.