A Pilates instructor says this is the one exercise you should add into your routine to build core strength

Incorporating some core-strengthening exercises into your workout routine is always a good idea.

The core includes muscles like the abdominals, lower back, pelvis and obliques—more or less the entire middle part of your body. This means that good core strength can help with more than just the appearance of your abs. It can support your posture, spine and hip health and even reduce back pain.

If you’re focusing on moves like sit-ups and crunches for your core workouts, Pilates instructor Jodi Montlake says it's time to change that—especially if you want to combat the upper-body "tightness" that plagues a lot of people.

"We see so many people with tight chests, back and shoulders because of their desk jobs," she explains. This tightness is caused by being in a curled-over position all day, in which your shoulders and upper body are hunched over. Sit-ups reinforce and repeat this movement pattern, because of their forward-curling motion.

"Our muscles get weak and relaxed when they're in the same position all the time. So, we want to try and do the opposite [movement pattern]," says Montlake.

For people who are new to Pilates, Montlake recommends trying an exercise known as 'scissors'. It engages similar core muscles to exercises like sit-ups, but it doesn't require that crunching motion which can be uncomfortable. "This move [scissors] targets the transverse abdominals and the back muscles," Montlake explains.

Scissors is often done with the head raised but Montlake says this isn't necessary to experience the strengthening benefits.

How to do the Pilates scissors

Sets: 3 Reps: 12

• Lie on your back on a yoga mat or a comfortable surface. Extend your legs out straight and place your arms by your sides.
• Engage your core and lift both legs up so that they form a 90° angle with your body.
• Lower your left leg towards the mat, but do not let it touch the floor. Keep it hovering a few inches above. Then switch legs to create a scissor-like motion. Alternate for a total of 12 repetitions.
• Your back should remain in contact with the mat throughout the movement. If you find that it's arching upwards, focus on engaging your core. You can also adapt the move by not lowering your leg so close to the ground or by bending your knees.

You don't need to completely cut out sit-ups and crunches as they can still have plenty of benefits. However, if you find them uncomfortable or simply want to add more variety to your core routine to target a wider range of muscles, it's worth giving this one a go.