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I did 50 oblique crunches a day for a week — here’s what happened to my abs

Oblique crunch
(Image credit: Shutterstock)

There seems to be a new trend among fitness influencers at the moment, and it involves completely ignoring your oblique muscles. For those who snoozed through biology lessons at school, your obliques are the muscles that run along the side of your stomach. You have internal and external oblique muscles — the two work together to move the trunk, spine, and core. 

As a runner, a strong core is important to me both in terms of running strong and running quickly. When you’re running, your oblique muscles control the rotation of your upper body and torso, tying the upper and lower body together as you move. That said, I set about to strengthen my obliques by doing 50 oblique crunches on each side, every day for a week. Read on to find out what happened. 


A reminder that 100 reps of any exercise is an awful lot, and what works for me and my body might not work for you. If you’re new to an exercise, or you’re returning to exercise following an injury, it’s a good idea to consult a personal trainer to check your form before increasing the number of repetitions you do. 

Looking for more workout inspiration? Read what happened when I tried Lily James’ 600-rep ab workout, when I dug out my resistance bands and gave Chris Hemsworth’s Thor resistance band workout a go, and when I added 100 dead bugs to my daily routine

How to do an oblique crunch 

To do an oblique crunch, start by lying flat on your back, with your knees bent and your feet flat against the floor, as you would for a normal crunch. Put your hands behind your head, supporting your neck. Drop both knees to the left side, making sure your hips are still on the mat, and your legs are together, one on top of the other. 

Engage your core and crunch upwards, squeezing your abdominals to lift your torso — you should feel this along the right side of your stomach. Once you’ve completed your reps, drop your legs down to the right side, and repeat — you should feel this along the left side of your abdomen.

an illustration of a man doing oblique crunches

(Image credit: Shutterstock)

Remember, this exercise is working on your core — don’t use your hands to pull your head and neck upwards. If this version is too intense, keep your feet grounded and your knees bent and your arms extended up above you. As you crunch up, bring your arms to the left side of your knees, complete all your repetitions, then repeat on the right.

I did 50 oblique crunches a day for a week — here’s what happened to my abs 

Sometimes, it’s the little exercises that look simple that burn the most, and this is definitely true for oblique crunches. 20 reps in, I realized that this one was going to be really torch my abs, and I wasn’t wrong. 

The key for this exercise is to keep the movement slow and controlled to ensure your form is correct — if not done correctly, you won’t be targeting the abs, and risk putting strain on your neck. I opted for two sets of 25 reps on each side, with short breaks in between to ensure I was focusing on my form, not racing through the workout. 

I'm not naming names, but in the past, I’ve heard fitness influencers say they avoid oblique exercises as they can create a ‘boxy’ figure, and that the key to an hourglass physique is to ignore the obliques. Speaking to personal trainer Lucy Gornall, she disagreed with this sentiment, saying, “this is odd in my eyes as all muscles should be given attention for a well-rounded workout.” 

As the week went on, I found the challenge got a little easier, but a lot more boring. On the final few days to really up the intensity, I went for oblique v-ups, which really torched my core, and worked the side of my body hard. To do an oblique v-up, lie on your side with your knees bent and your legs stacked on top of one another. Put your bottom arm on the floor outstretched, and the top arm behind you head. Using your obliques, crunch up in a V, crunching the elbow of the top arm to your knees. 

an illo of a woman doing an oblique v up

(Image credit: Shutterstock)

Seven days later, did I have the abs of my dreams? Sadly not, no amount of crunches can sculpt a Chris Hemsworth-style six pack — visible abs are a result of a low body fat percentage (here’s how to work out your body fat percentage and why it matters). That said, I did feel like I’d worked my core harder, and realized that often, I tend to neglect my obliques in workouts. 

Doing the crunches before heading out for a run helped me to think about my form as I moved — keeping my abdominals engaged and my torso upright, rather than slouching into my stride. The oblique crunches are here to stay, I just won’t be doing them every single day from now on. 

Jane McGuire
Jane McGuire

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 four 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.