When sitting upright on the cushion, the feet are fixed in the holder with the knees slightly bent (feet pointing upwards), the outstretched arms are held diagonally forwards towards the feet (or only up to the shins). The torso bend (sit up) is performed with the knees initially slightly bent on the way down, whereby the upper body is lowered with a straight back to a position approximately parallel to the floor (or even lower with a good level of training). As the upper body is lowered, the arms are folded across the chest at the same time. Once you have reached the end position, quickly straighten your knees and catapult your upper body upwards to return to the seated position (stretch your arms out again at the same time and bring them to your legs/to the rack).
Attention:
The GHD sit up is a great exercise for training the abdominal muscles statically and the hip flexors dynamically. When setting up, ensure that the hip joint can move freely. It is important to extend the knees on the way up in order to engage the straight muscle of the thigh (m. rectus femoris) as the primary hip flexor. Those who do not force knee extension will not use the m. rectus femoris primarily as a hip flexor and will therefore work via other hip flexors, such as the m. iliopsoas. However, as this attaches to the spine, stress can be placed on the back and pain can be felt. With the GHD sit up, it is important to understand that it is not the bending of the spine (as with the crunch), but the active keeping of the spine straight (static working of the abdominal muscles) during the movement that should provide the training stimulus for the abdomen.
Lighten:
Caution is advised with the GHD sit up: Firstly, 30+ regular trunk bends should be mastered. The next step is to be able to hold the horizontal on the GHD for 30+ seconds. Then practise the GHD sit ups slowly with increasing ROM (range of motion), if necessary with the support of a partner. For the first few training sessions, a maximum of 10 repetitions per set will suffice.
Harden:
Execution down to the floor (lower your upper body beyond the horizontal); stretch your arms above your head (held high instead of folded on your chest); hold additional weight in your hands.
