oblique twists with medicine ball on decline bench.
if you don’t have a medicine ball you can use a plate or a dumbbell for this move.
start out with your feet locked into the decline bench and hold the weight close to your chest.
excuse the goofy face.. and twist one way, keeping the weight close to your chest and “reaching” with your elbows toward the sky.
i like to do 3 sets of 25 reps on each side, or 50 reps total.