If you want to practice this exercise at home, it's a good idea to ask a friend to hold your legs firmly while you raise and lower your upper body. For this, you could use an armchair as an extension bench, for instance.

At the start of the exercise, hang your upper body downwards. Before straightening up, place your hands on your head and slowly lift and lower your torso.

For a start, you could do this exercise with approx. one or two sets of not more than 15 repetitions.