This 90-rep squat challenge only took four minutes, but it worked lower-body muscles I didn't know I had

Squats are one of the best exercises out there when it comes to building strength in the legs. With lots of variations on the classic lower-body exercise to keep things interesting, there are many benefits of squats and you can use them to develop muscle in your quads, glutes, calves, and hamstrings.

I regularly incorporate squats into my lower-body workouts, so when I noticed that personal trainer and Sweat app founder Kayla Itsines had posted a squat challenge on her Instagram page, I knew I had to give it a go.

It involves nine squat variations, with a combination of bodyweight and dumbbell versions to try. You do 10 repetitions of each, totaling 90 reps overall. It sounded like an achievable challenge, so I tried it after doing my regular leg day workout.

I opted for a 10KG dumbbell for the weighted exercises, and set a timer to see how quickly I could get through the workout.

Watch Kayla Itsines' squat challenge

After just the first 20 reps of this workout, my legs were already burning and my glutes in particular were on fire. It was difficult to maintain good form, making sure my hips dropped below parallel and my chest stayed upright, as my legs became more and more fatigued.

I took regular breaks to shake out my legs before going back into the workout, to ensure I didn't compromise on form. If you're new to this bodyweight move, or could use some technique pointers, learning how to do a squat to get your form right can make a big difference.

I'm used to completing weighted squats, but they felt particularly challenging when my legs were already tired during this workout. The jumping squats were by far the most difficult move, however, putting both my strength and my endurance levels to the test.

The narrow squats were a more unusual variation for me and they targeted my quads (the muscles at the front of the thighs) more than the other exercises, so I'll definitely be adding them into my routine to switch up my sessions.

For a full leg workout, I think I could have repeated this workout three to four times. But as I'd already done an hour-long session before this one, I decided to just complete it once and I managed to do it in just under four minutes.

If you like a bit of competition, you don't need long to give it a try and see if you can beat my time. But whether it takes you four, five, or 15 minutes, the key is to move in a way that feels right for your body and allows you to do each squat with proper form.

And if you want to increase the challenge, you could increase the dumbbell weight. If you're at the gym, there are plenty of fixed weights available, but the best adjustable dumbbells are a great option for at-home training.

These customizable dumbbells combine several weights in one for convenient storage and you can quickly adjust the load between exercises, or gradually as you get stronger.