The idea of firming up your middle may seem daunting, particularly if you don't have 20 minutes to dedicate solely to strength training. But cranking out 30 crunches after a run or HIIT workout isn't going to do much — you have to do the right kind of ab moves in order to hit those hard to reach middle muscles. Enter: the crossover crunch.
"The crossover crunch is great because it works every part of the abs," Ngo Okafor, a celebrity trainer and founder and owner of ICONOCLAST Fitness in New York City, told POPSUGAR. "It works the upper part of the abs, the obliques, and the lower abs." You can do this move with or without a pair of dumbbells, depending on your fitness level. For beginners, start without weights and then as you get used to the exercise, try a pair of 5- to 10-lb. weights to kick up the intensity and burn.
To do this exercise, start by lying on the floor with your knees bent, as if you were doing a traditional sit-up. If you're using dumbbells, keep your arms bent at a 90-degree angle by your chest. As you contract your ab muscles, perform a sit-up, twisting your torso to one side as you punch across your body with the opposite arm. Return back to the starting position and repeat. Okafor recommends 15 to 20 reps on each side, making sure to do all the reps on one side before moving to the other. To make the exercise even more challenging, straighten your legs and extend your arms overhead, reaching the opposite hand to your foot as you lift your shoulders off the floor.
"This move is so effective because the process of raising the arm and shoulders successfully hits the upper ab region," Okafor said. "The twisting motion works the obliques, and if you do this exercise with straight legs, you're able to hit the lower abs as you contract and bring your arm to reach the opposite leg."