1, in the absence of a horizontal bar, you can use the protruding part of the skylight at the upper part of the door frame as a horizontal bar and climb with your hands to do pull-ups.

2, you can also use the edge of the wall at home, stick the back of your hand to the wall, then practice lifting your legs and lift your thighs and calves to your head together to enhance the exercise intensity of abdominal muscles and enhance the pull-up function.