Milos would you suggest doing this exercise once in awhile or often? I am eager to try it on my next leg day but want to know if it should be included regularly.
I would suggest OFTEN - if you feel right doing it...
Remember - keep your knees/hips/shoulders in the same line...go very slow (controlled) all the way down.
In bottom position pause for two seconds while maintaining maximal contraction in your quads and than slowly (without any momentum) push your way up...
At the top stop short of locking your knees...