Cable Side Bends

Side bends work your oblique muscles. Most people do it with a dumbbell, but I prefer to do it with a cable instead. With a dumbbell, as it's close to your body, you have to use a very heavy dumbbell to make it effective, I would need a dumbbell heavier than most gyms have and even then there isn't much resistance at the top when you're upright. Grip could also be an issue when using dumbbells

When using a cable, the angle of the cable forces you to work hard to stand upright between reps. You don't get to rest and so you have more time under tension. You won't need anywhere near as much weight. 
 
How to do a Cable Side Bend

• Set the attachment set as low as it goes, ideally around ankle height.  
• Grab the handle of the cable and a distance away from the attachment so your arms 45 degree angle from the floor. Stand with a stance where you feel balanced
• Bend your torso sideways towards the direction of the cable until you feel a stretch on the other side of your torso. Reverse the movement until you're upright again. Make sure you don't rotate your body at all.