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I did 100 flutter kicks a day for a week — here's what happened

a woman doing flutter kicks
(Image credit: Getty/Maridav)

When it comes to working your abdominal muscles, not all exercises are created equal.

While some exercises will target your rectus abdominis — the outer abdominal muscles that hold your internal organs in place and create the appearance of the ‘six pack’ many crave, others will hit the transverse abdominis, the deeper core muscles that play an important role when it comes to stabilizing the trunk and protecting your spine. There’s also the obliques that run along the outside of your waist and allow you to twist and turn.

A good ab workout will target all of the muscles in your trunk to sculpt a strong core. 

One exercise that does a good job at hitting the mid and lower abdominal muscles is flutter kicks, or butterfly kicks. They also help build strength in the hip flexors and lower back, as well as the quads, glutes, thighs and adductors. They mimic the motion of swimming, without you needing to travel to the pool. To find out more about this underrated ab exercise, I did 100 butterfly kicks a day for one week. Read on to find out what happened.

As a fitness editor, I’m no stranger to a weird and wonderful workout challenge. If you’re looking for more inspiration, read what happened when I did 100 dead bugs a day for a week, or when I added 30 sit-ups a day to my ab workouts for 30 days. Plus, if you’re looking for the best ab exercises, here’s the seven exercises Chris Hemsworth’s PT recommends. 

an illustration of a woman doing flutter kicks

(Image credit: Getty/Oleksii Bulgakov)

What are flutter kicks? 

Flutter kicks, or butterfly kicks, are a bodyweight exercise, so you can leave your adjustable dumbbells to one side for this one. To do a flutter kick, lie on your back with your lower back pressed into the mat — don’t allow your lower back to peel off the mat at any point during this exercise.

Place both your hands underneath your glutes, with your palms pressed into the mat, and raise your feet a few inches off the ground. Raise your left leg up, then your right, as if you are kicking your legs during backstroke. Keep your core engaged for the entire exercise (here’s what that means and why it matters). To make the exercise harder, raise your head and neck off the floor as well. 

Flutter kicks are different from scissor kicks, where you criss-cross your legs in a horizontal motion, crossing them over one another. Scissor kicks are slightly more challenging, as they force you to use your adductor muscles to control the horizontal movement. 

I added flutter kicks to my daily ab workout — here’s what happened 

I’ll start this article by stating that pre my 100-reps-per-day challenge, I’ve never been a fan of this ab exercise. Give me dead bugs, crunches, or planks any day of the week. This might be down to the fact I suffer with sciatica, so I have to be mindful of putting my lower back under too much strain during ab workouts. Flutter kicks and scissor kicks aren’t the most lower-back friendly ab exercise, so I often swap them out when I see them on my workout plan. 

That said, never one to shy away from a challenge, I used this as an opportunity to really think about my form during the exercise, by slowing the movement down and focusing on pressing my lower back into the floor. On day one, I started with five sets of 20 butterfly kicks. Due to my back issues, I raised my legs to a 45 degree angle for the exercise, rather than hovering them a few inches off the ground. 

On day two and three, I repeated this, using the flutter kicks as part of my pre-run warm up. During my dead bug challenge, I realized that doing ab exercises before I set off for my run helped me engage my core muscles more as I ran, forcing me to think about keeping my torso upright, in turn helping me run with better form. I didn’t feel the butterfly kicks worked my abs as hard as the dead bugs did, but they definitely targeted my lower abdominal muscles. 

On day four, I traveled to New York and realized, slightly jet lagged, I hadn’t done my butterfly kicks before I collapsed into bed. For the sake of good content (thank me later) I unrolled the exercise mat left in the room (next to Lululemon’s Mirror, which I was pleasantly surprised by) and did two sets of 50 flutter kicks, slightly faster than I had on previous days, but I was desperate to sleep. Days five and six followed the same pattern — fitting the flutter kicks in around my schedule, but I found I didn’t dread them in the same way I had at the beginning of the week. I was also getting quicker. 

On day seven, disaster struck. After sitting down for seven hours on a long haul flight and carrying a heavy backpack around the city, my sciatica flared up big time, and I had shooting pain in my hip. After ten reps of flutter kicks, I abandoned this challenge, as they hurt, and even with my legs raised higher, I decided the pressure on my back was too much. Instead, I swapped them out for toe taps. 

Lessons learned from this challenge? Firstly, if you hate an exercise, modify it and think about your form. Six hundred flutter kicks taught me that they are a great exercise to do as part of my running or training warm-up, as they really force me to brace my core but also engaged my quads and lower body. Of course, nothing really changed aesthetically — as I’ve mentioned before, defined abdominal muscles depend on a low body fat percentage (here’s how to calculate your body fat percentage), so no amount of dead bugs or sit-ups will make your ab muscles pop. 

Secondly, don’t be afraid to skip or swap an exercise if it doesn’t work for your body. Everyone is different, and what works for that trainer you follow on Instagram might not work for you right now — don’t be afraid to modify your workouts, having a strong and healthy body is more important than any workout challenge. 

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.