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Are Crunches Effective For Building A Six-Pack?

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When looking to attain an Adonis-like set of abs, many people still automatically turn to the age-old method of busting out as many crunches and/or sit-ups as possible. But while both exercises will indeed work your abs, neither is close to being the best way to do so.

The classic crunch involves just lifting your shoulders and head up off the floor, which doesn’t enlist all of your core muscles – your lower abs in particular are uninvolved in the movement. The sit-up, which involves lifting your entire torso up off the ground, does recruit more midsection muscles, but in doing so increases the risk of injuring your spine through the repeated movement of curling up and down.

For a truly effective core session, you should be using big compound lifts and hitting your abs from as many angles as possible with variations on the standard sit-up and crunch.

Below you’ll find a range of crunches to try – but first, check out this primer on the exercise from Paul Humphries, personal trainer at TRAINFITNESS (opens in new tab).

How effective are crunches as an abs exercise?

Crunches may feel effective while you’re doing them but they are generally not the best exercise for your abs. Varying the planes of movement, angles and positions will result in the most benefit for your core.

What other exercises are more effective?

To gain a stronger core, compound movements like squats and deadlifts, when done properly, will strengthen your abs and core. A simple exercise which is great for engaging the core is the plank. Try activating your core before a workout to gain the most from compound lifts.

Are there any dangers to doing crunches if your form is wrong?

Rounding the back is a common fault when doing crunches. To ensure this doesn’t happen, trying looking up towards the ceiling and maintaining tension within your whole core throughout the movement. And if you suffer with back problems, avoid doing crunches. Instead focus on developing a strong plank hold first and then progress to crunches.

What is a good variation on the standard crunch people can do?

reverse crunch is a great alternative. Start by lying on your back with your knees bent. Draw your bent knees into your chest and then extend your legs back out and touch your heels to the floor. Make sure you force your lower back into the floor to avoid rounding your back.

Crunch Variations

Abs Crunch

Lie on your back on a mat. Bend your knees and keep your feet firmly placed on the floor. Keeping your hands folded across your chest and your lower back fixed to the mat, raise your shoulders and the top half of your torso until you begin to feel a stretch in the upper portion of the abdominals. Lower slowly.

Bicycle Crunch

A superb core workout, this crunch variation brings all kinds of abdominal muscles into play, including the tricky-to-target obliques. Lie on the ground with your head and shoulders slightly raised and your hands resting lightly on the side of your head. Lift one leg just off the ground and extend it out. Lift the other leg and bend the knee towards your chest while twisting through the core and moving the opposite elbow towards the knee (they don’t need to touch). Lower your leg and arm at the same time while bringing up the opposite two limbs to mirror the movement.

Reverse crunch

Your lower abs are harder to hit than the upper abs, but this move targets them by using your legs for resistance instead of your torso. Keep the back of your head and shoulders in contact with the ground and lift your lower back off the floor. Bring your knees towards your chest, then squeeze your abs for two seconds and reverse to the start.

Crossover crunch

This is a variation of the oblique crunch (below), with a shorter range of motion to make it slightly easier. Lie flat on your back but with your right leg crossed over the other. Keeping your neck neutral, curl your left arm, shoulder and chest towards your middle, then lower slowly.

Oblique crunch

Hitting your core from the sides takes the focus off the muscles down the middle of your stomach and ensures that all the muscle fibres in your midriff are working. Lie flat on your back but with your hips turned so your weight is on your right. Keeping your neck neutral, curl your left arm, shoulder and chest towards your middle, then lower slowly. Repeat on the other side.

Gym ball crunch

Lying on a gym ball works your core harder to stabilise your body and allows for a greater range of movement when doing the crunch. Lean as far back on the ball as you can to arch your back in its natural range, then contract your core to bring your upper body off the ball.

Medicine ball crunch

This crunch variation improves the strength and flexibility of your arms and shoulders, as well as working your core especially hard thanks to the additional weight of the medicine ball. Lie down and hold a medicine ball in both hands above you, with your arms fully extended. Keep your arms straight as you raise your torso, the, as you come back down, take your arms behind your head so the medicine ball touches the ground. Raise the ball back to the start and go straight into another rep.

Weighted crunch

Adding weight and slowing down the standard crunch will give your abs a better, safer workout than doing a high volume of reps. Hold a dumbbell on your chest. Keeping your neck neutral, squeeze your abs to curl your upper body off the floor. Pause, then lower slowly.

Weighted crunch reach

You can use pretty much any weight for this exercise, as long as you can hold it in both hands comfortably. Whether you opt for a dumbbell, kettlebell, sandbell or weight plate, don’t go too heavy at first – even adding a small amount of weight to your crunches makes them very tough indeed by the end of a set. Lie on your back with your knees bent and hold the weight above you in both hands with your arms straight. As you perform the crunch, reach up with the weight as high as you can. Pause at the top of the movement, then slowly come back down, still keeping your arms straight.

Dumbbell pull-over crunch

You’ll need to build the fast-twitch muscles in your abs to get a killer six-pack, and this heavy resistance move will do the job (just make sure your core is warmed up before doing it). Lie flat, holding light dumbbells or a weight plate in your hands. Contract your core as you bring the weights and your legs together. Pause then lower slowly to the start.

Cable crunch

Driving down against the constant resistance of a cable machine keeps the muscles under tension for longer, helping them grow stronger. Use a high cable and rope handle. Lean forwards, keeping your body straight and your arms and hips locked in position, then crunch down, using your abs as the driving force. Pause, then reverse the move slowly.

Nick Harris-Fry is a journalist who has been covering health and fitness since 2015. Nick is an avid runner, covering 70-110km a week, which gives him ample opportunity to test a wide range of running shoes and running gear. He is also the chief tester for fitness trackers and running watches, treadmills and exercise bikes, and workout headphones.