An isolation exercise for the oblique muscles.
Lie down on your back and fix your feet in position (for example, put them under a bench or ask your partner to hold your feet).
Bend your knees.
Raise your body so that there is a V-shaped angle between the body and the hips.
Grasp a barbell plate.
As you exhale, turn your body to the right keeping your hands and the plate parallel to the floor. Pause for 1-2 seconds.
As you inhale, return to the starting position and repeat the crunch to the left.
Your arms should be parallel to the floor.
Keep your torso and back straight, don't swing.
The straighter your arms are, the more load is placed on both abs and arms.