Forget sit-ups — it only takes 7 exercises and 20 minutes to sculpt a strong core

a photo of a woman holding a plank
(Image credit: Getty/Oleg Breslavtsev)

We’ve said it before and we’ll say it again — when it comes to working your core, not all ab exercises are created equal. If you’re looking for a workout that’ll sculpt the muscles in your midsection, look no further, as we’ve found a quick core workout that’ll blast your abs. Use it as a workout on its own, or add it to your next upper/lower body workout as a quick finisher. Read on to find out more. 

The workout, created by fitness coach and qualified personal trainer, Caroline Idiens, only uses seven exercises, which are repeated for three rounds in this 20-minute workout. You’ll work for 40 seconds, then take a 15-second break. If you’re looking for a more advanced ab workout, increase this time to 45 seconds, and shorten the break. 

As always, it’s worth highlighting that while strong abs have a number of benefits, including better posture, and protecting your spine from injury, if visible abs are your goal, no amount of planks or crunches alone can change the physical appearance of your midsection. Visible abs are the result of a low body fat percentage — diet, sleep, hormones, cardio levels, and stress can all impact your body fat percentage. Here’s how to calculate your body fat percentage, and why it matters

What is the workout?

Ready to get started? As mentioned above, you’ll do each exercise for 40 seconds, followed by a 15-second rest, for three rounds.

Low plank knee taps

For this exercise, start in a low plank position, with your body weight on your elbows, which should be stacked underneath your shoulders, your core engaged, and a straight line down your back from your head to your heels. Squeeze your core to hold this position, then tap one knee down to the floor, before returning to your starting position and switching sides. 

Clap unders

Start by lying on your back, and engage your core to raise your head, neck, and torso off the mat, as if you’re doing a sit-up. As you raise your trunk off the mat, bend one knee, bringing it in towards your chest. Clap your hands underneath your raised leg, before lowering back down to your starting position. Repeat on the opposite side. 

Low plank dips

For this exercise, start in a low plank position. Engage your core, and lower one hip down towards the ground — it doesn’t matter if it doesn’t touch the ground, before rising back to your starting position. Then repeat on the other side. Here’s what happened when we did 50 hip dips a day for a week

Straight leg crunches

For this exercise, start by lying on your back with your arms and legs outstretched. Engage your core, and lift one arm and one leg up off the mat, touching above your stomach, before lowering yourself back down to your starting position. Switch and repeat on the opposite side, and continue to alternate between sides. 

Wide tucks

Also known as a Spiderman plank, this one really works the obliques. Start in a high plank position, with your elbows and wrists stacked underneath your shoulders, your core engaged, and a straight line from your head to your heels. Raise one foot off the ground, and bend at the knee to bring your knee to your elbow. Return to the high plank position and repeat on the other side. Keep your core engaged throughout, and don’t let your hips dip. 

In and outs

For this exercise, start by lying on your back, and place your hands behind your head. Engage your core and raise your head off the ground — ensure that this lift is coming from your core, and that you are not pulling on your neck. Raise your feet a few inches off the floor, and tuck both legs in towards your body, bending at the knee, before straightening them back out to your starting position.

Russian twists

To do a Russian twist, sit on an exercise mat and engage your core as you lean backward, lifting your legs off the floor, so you are in a V-shape position. You can cross your legs if it helps, and knot your hands together in front of your body. Bracing your core, twist your torso from side to side, and think about lowering your hands to the side of you as you twist. Follow your hands with your eyeline. Continue to twist from side to side without dropping your legs to the floor. Here’s more on how to do a Russian twist, the benefits, and the modifications to try

What are the benefits? 

As mentioned above, this workout targets all of the muscles in your core, including the obliques, which run along the side of the body, the rectus abdominis, often referred to as the outer ‘six-pack’ muscles, and the transverse abdominis, which are the deepest core muscles. Strong abdominal muscles are far more than just an aesthetic goal — they can protect your spine from injury, help you walk and sit with better posture, improve athletic performance, and help reduce lower back pain.

Doing abdominal exercises like planks can also help you work on your overall stability and balance — especially important if you’re a runner, or playing sports. Moving with better stability can help you avoid injuries, and move more efficiently on the field. 

What’s more, You use your core in most day-to-day activities, from bending down to tie your shoes, to lifting something from the shelf, so core workouts are often great for functional fitness. Here’s everything you need to know about functional training

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Jane McGuire
Fitness editor

Jane McGuire is Tom's Guide's Fitness editor, which means she looks after everything fitness related - from running gear to yoga mats. An avid runner, Jane has tested and reviewed fitness products for the past five years, so knows what to look for when finding a good running watch or a pair of shorts with pockets big enough for your smartphone. When she's not pounding the pavements, you'll find Jane striding round the Surrey Hills, taking far too many photos of her puppy.