You've probably heard the phrase "engage your core" once or twice or maybe, you know, a hundred times. (If not, here's a quick refresher [1] on what it means.) That's an important trick to keep in mind during ab workouts, but it's also not everything. If you're still not seeing or feeling the results you want in your abs, you're going to want to take it one step further.

"The most important thing is to learn how to get tension into your abdominals, no matter what you're doing," said Ryan Johnson, NSCA, personal trainer and co-founder of Homage Fitness [2]. The way to do that, he explained, is by "pulling" your ribs down. "Think about if your hands were on your ribs and you kind of had to pull your ribs down to protect your internal organs. That's a way that your core can actually activate."

One of the best ways to learn how to feel this tension and start to sculpt strong, tight abs, is a classic: the plank [3]. You want to pull your ribcage down, Ryan said, and try to get a slight tuck to your hips so that your body is fully in line. Eric Johnson, an NSCA-certified trainer and fellow co-founder of Homage Fitness, told POPSUGAR that to get full tension and results from your ab workouts, "You want to start off with those exercises that actually don't flex or rotate the spine." Along with planks, he also recommended:

• Side plank
• Hollow hold
• Dead-bug
• Pallof press

It's all about holding tension through the whole exercise and resisting any extra movement. For example, Ryan said that in a dead bug exercise, "your back's going to want to come off the ground. So you want to keep trying to push that down and resist any rotation, and that's really teaching your core how to integrate."

"A lot of people think that they really have to burn out the core with high reps," Eric said. But if you do a plank while forcing tension through your whole body, Ryan explained, "You can't actually hold that position longer than about 60 seconds." Maintaining a hold for a short amount of time, or performing a lower number of a similarly high-tension move, is going to be much more beneficial "than trying to power your way through these massive reps core routines."

Scroll ahead to learn how to do each of these ab and core moves. Try adding two or three to the beginning of your workout to activate your core, or perform them all for a short, intense ab workout. Want more? Check our other favourite core-activating exercises here [4] and this fast, intense four-move ab workout [5].

Elbow Plank

• Balance on your forearms and toes with the body in one straight line, elbows underneath the shoulders.
• Hold for one minute, keeping tension in your core throughout.

Side Plank

• Sit on your left side with your legs slightly bent and your feet stacked.
• Place your left hand about 12 inches from your pelvis.
• Push your hand into the ground and straighten your legs as you lift your pelvis off the ground. If you have trouble balancing, stagger your feet so the top leg is in front.
• Hold for 30-60 seconds and switch sides.

Hollow Hold

• Begin on your back with your legs straight and your arms extended overhead.
• Actively press your lower back into the floor and draw your belly button into your spine.
• Inhale to slowly lift your shoulders, arms, and legs off the floor. Keep your hands and heels as low to the ground as possible, while still pressing your lower back into the floor. Maintain tight abs and glutes. It's OK to bend your knees if straight legs are too challenging.
• Hold for five to 30 seconds to complete one rep.

For an extra challenge, try a hollow body rock [6] instead.

Dead Bug

• Lie on your back with a neutral spine and your hips and knees at right angles with your palms pressed into your thighs just above your knees.
• Pull your abs to your spine keeping your ribs and pelvis still as you lengthen your right arm and leg out until they are almost parallel to the floor. Keep your torso and spine completely stable as the arm and leg move.
• Return to the starting position, and repeat on the left side to complete one rep.
• Do six to 12 reps for a total of two to three sets.

Pallof Press

• Lower the carriage of a cable machine so that it's about chest height, and attach a D-handle to the pulley. Adjust the weight so that it's at 10 pounds. If this is too heavy or too light, feel free to change the weight.
• Standing with the left side of your body closest to the machine, grab the handle with both hands and take two or three steps out so that there's tension on the cable. Hold your hands at your sternum, and make sure that your body is square. If you feel like you're getting pulled to the left, this is an indicator that you should lighten the weight.
• On an exhale, press the cable straight out in front of your body. Be sure not to rotate towards the machine. Hold for two seconds before returning to the starting position. This counts as one rep.
• Complete two to three sets of six to 12 reps on each side.