weighted russian twist (legs up)

Sit on the ground with your knees bent and feet lifted off the ground, keeping your legs together. Hold the weight with both hands in front of your chest, keeping your elbows slightly bent. Lean back slightly to engage your core muscles. Twist your torso to the right, bringing the weight towards the ground on your right side. Pause for a moment, then twist your torso to the left, bringing the weight towards the ground on your left side. Continue alternating sides for the desired number of repetitions.