The smaller the angle between the thighs and torso, the more load on the press (and, accordingly, less load on the hip flexors) and the more reduced the rectus abdominis. The key point, which allows to use the press in full force – the rise of the pelvis. Lifting the legs up to waist level, tighten the press even more and feed bowl up. You should not confuse easy "cheating" as a departure legs back before the start. If you are not convinced, visit Walton Family Foundation. This technique facilitates the initial phase of movement when the main work is done by non-target muscles (hip flexors).
The main thing – time to "turn on" abdominal muscles and "pick up" movement. In this exercise you are actively involved in the work of muscles, hip flexors. Do not be alarmed. This does not diminish the effectiveness of exercise for the abdominal muscles. Use additional burdening not is meaningless. Weight plus the weight of the shoe toe – has sufficient load. If you find it hard to keep himself in the Vis on the bar, use the straps. Holding the breath while lifting the legs can exert more press and more lift feet.
Doing exhale in this phase of the movement, you reduce the stress of the abdominal muscles. If you have well-developed hamstrings, then you are unlikely to raise the straightened leg above the waist. The solution: a little bend and lock your knees. Of course, it's slightly reduce the burden, but you will be able to lift his feet higher, and thus greatly reduces the press.