I did 30 sit-ups a day for a month — here’s what happened

woman doing sit-ups
(Image credit: Shutterstock)

For a long time, sit-ups have been hailed as one of the most popular abdominal exercises, with them appearing on pretty much all of the best ab workouts out there. But if I changed nothing in my fitness routine other than adding 30 sit-ups a day, what would happen to my body? 

Call me your fitness guinea pig, I unrolled my yoga mat, moved my adjustable dumbbells to the side, and got ready to start my new sit-up routine. As a fitness editor, I already add quite a lot of movement to my day. In addition to walking for 90 minutes a day with my excitable (read, hyperactive) cocker spaniel, I also do three Pilates or strength sessions a week and run at least 20 miles. And since writing this article, I've also added a plank to my morning routine and check out how John Carroll got on with doing side planks every day for a week. (I also recently tried JLo's ab workout for a week).

Over the month, I mixed things up — sometimes I tagged the sit-ups onto the end of a workout, on other days, I did three sets of 10 sit-ups to break up long periods of being sat behind my desk at work (here are the best exercises to do if you sit down all day), and on one particular Sunday, I realized as I was getting into bed I hadn’t done my daily sit-ups and begrudgingly did them in my pajamas (don’t say I’m not dedicated). 

But did they leave me with a rock-solid core, or was it a big waste of time? 30-days later, the results are in. Here’s what happened when I did 30 sit-ups a day for a month: 

What happened after 30 days

I’ll cut to the chase, nothing changed visibly after 30 days of sit-ups. I’ve been writing about fitness for long enough to know that abs are made in the kitchen, not on the yoga mat, but I was hoping for something to show for my challenge. 

It turns out that despite the popularity of this abdominal exercise, it’s not actually the best at working your core. In fact, it’s one of the worst ab exercises out there, and according to Harvard Health Publications, sit-ups can be potentially damaging to the spine.  

Medical professionals explain that when you perform a sit-up, you’re pushing your curved spine into the floor while flexing upwards. If you suffer from tight hip flexors or sit down a lot, your hip flexors can tug against your lower back during this upward motion, creating pain or discomfort in the lower back. It’s thought to be even worse if you perform sit-ups with your hands behind your head and almost pull your body upwards. 

I suffer from sciatica after a horse-riding accident as a teenager, so often have to be careful while doing abdominal exercises. I performed my sit-ups with my arms crossed across my chest, and while I didn’t experience bad lower back pain in my 30-days, I’d warn against this challenge for anyone who suffers from back issues.

In addition to not being particularly effective, I also found I got bored of sit-ups pretty quickly. Similar to a squat challenge, or a burpee challenge, this one again proved that actually doing one exercise a day for a month isn’t that fun, and isn’t really the solution to getting visible gains.

I learned how important it is to activate my core before running

That said, it wasn’t all bad. The sit-up-shaped silver lining here is that I realized how important it is to do some activation exercises before heading out for a run. I’m a lazy runner, and will often roll out of bed, grab my running shoes and headphones, and just go. On my running days, I’d do my sit-ups before leaving the house, so I could jump in the shower and get back to my desk as quickly as possible when I got home. 

I soon realized how much better I felt having done some activation exercises — doing the sit-ups made me think about engaging my core on the run, improving my running posture, and stopping me from slouching at the shoulders on easy running days. By the end of the challenge, I was also adding some glute bridges and dead bugs into my pre-running routine, and this is something I’ll continue, although I’ll probably scrap the sit-ups going forward. (If you're what happens when you do 100 dead bugs a day for a week, we've got the answer.)

I enjoyed breaking up my day with movement 

Last, but by no means least, I enjoyed breaking up my day with short bursts of movement. Like many others, I spend a lot of time sitting behind my laptop, and stopping to do just 10 sit-ups helped me reach my Apple Watch movement goals and break up the time sat down. 

While I probably won’t be sticking to the daily sit-up routine going forward, this challenge reminded me that shorter bodyweight sessions can be an effective way to add some movement to your day-to-day. Plus, they’re entirely free and can be done from anywhere (although don’t blame me if you get weird looks in the office).  

Read what happened when I took cold showers after every workout for a week here, I did 50 oblique crunches a day for a week — and here's what happened to my abs and here's when I tried the viral 25-7-2 workout for a week

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.