How to do a dumbbell crossover punch:
- Begin by lying on your back with your knees bent and your feet flat on the ground, about two feet from your butt. Hold weights, five- to eight-pound dumbbells, in both hands at your chest with your elbows on the floor.
- Keeping your hands at your chest, roll up to a sitting position. Twist your ribs to the left as you "punch" your right hand to the outside of the left knee.
- Bring the right hand back to your chest as you untwist, bringing your torso back to the center, and roll down to the ground.
- Repeat the sit-up, twisting to the right side to complete one rep.
- Do 10 reps total.