3 common ab workout mistakes that are slowing your results

• Trainers see many of the same mistakes regularly when it comes to core training.
• Personal trainer Faisal Abdalla told Insider three of the most common ones, and how to fix them.
• For example, you shouldn't add "twists" to your sit-ups.

Training your core is important not just for building rippling abs, but also for supporting your body in other exercises.

However, trainers often see common movements performed incorrectly, meaning people aren't getting the benefits they should.

Personal trainer Faisal Abdalla told Insider three of the most common ab-training mistakes people make, and how to fix them.

1. Adding a 'twist' to sit-ups

The mistake most people make when performing sit-ups is adding a "twist" at the top, according to Abdalla.

"Most people do this because they think it works the muscles on the side of their waists (the obliques)," he said, but that's not the most effective way to train.

Instead, you should stick to one plane of movement per exercise.

An exercise like a Russian twist, where the whole movement is on the diagonal, is effective as you move in a rotational (twisting) plane only, Abdalla said. But when you twist at the top of a "straight" sit-up, you lose tension immediately in the abdominals and it transfers to the oblique.

"So when doing a traditional straight sit-up, stick to that single plane movement to keep the focus on that one area of your abdominals," he said. "Adding a twist isn't bad, it's just not as effective. If you want to do twisting abs, just do twisting ab exercises."

2. Lifting your hips in a plank

When performing a plank, people often lift their hips upwards, or collapse through the shoulders, but both of these are incorrect.

"It might make the exercise easier, but it'll negate the move's core-strengthening benefits," Abdalla said.

When you lift your hips in a plank, it breaks the tension in your core and puts more stress on your upper body, he said.

Push up through the shoulders and upper back, and aim to form a straight line from your shoulders to your hips to your ankles.

"Keep those shoulders over your wrists and glutes tight," Abdalla said, and he recommends asking a friend to check your form from the side.

3. Sitting too far forward during Swiss ball crunches

Swiss balls - large inflatable balls - are often used to perform crunches, but it's important to position yourself right to get the benefits of the exercise.

"Rather than lie back on the ball, a lot of people sit upright, lean back slightly, and then almost 'rock' backwards and forwards," Abdalla said. "Rocking, sadly, is not an efficient route to rock-hard abs."

Instead, Abdalla advises lying back on the ball so you're looking up at the ceiling rather than across the room. When you crunch, keep your chest open and facing the ceiling to maintain tension throughout the movement.