This exercise focuses on core strengthening, the hanging knee raise exercise targets the lower abdominals, hip flexors, and lower back.
The upper back and shoulders muscles are contracted in this movement for stability.
Its best to keep your torso as stable as possible, don’t allow for your legs to swing back and forth. As this would mean that you would be using momentum to carry the lower body weight instead the muscle contraction from the core.
Try not to jerk the movement whilst moving the knees up to chest.