Erin Oprea, Nashville-based trainer to Carrie Underwood and Kelsea Ballerini, among other celebs, loves a great glute workout. Last week, Oprea posted an Instagram video of her demoing an eight-part, equipment-free workout that targets this muscle group from all angles.

You can check out the video , via @erinoprea, here:

"I was lying on the floor in my hotel room after a busy "Oprea says SELF of the inspiration behind this no-equipment sequence.

This circuit targets multiple muscles in the butt, plus many other muscles in your core and lower body.

This particular combo of moves is effective because they work "your butt from all different angles," says Oprea, and also strengthens your back, core, and hamstrings, she adds.

"It's a very intense circuit, " Stephanie Mansour, Chicago-based certified personal trainer, tells SELF.

As Oprea mentioned, this combo of moves will target all of the muscles in your butt, including your gluteus maximus (the biggest muscle in your butt), your gluteus medius (the smaller muscle on the outer side of your butt that supports the hip and rotational movement of the thigh), and your gluteus minimus (which helps with internal rotation of the hip). You’ll also work several major muscles in your core, including your transverse abdominis (the deepest ab muscle that wraps around your sides and spine), rectus abdominis (what you think of when you think abs) and obliques (muscles on the sides of your stomach).

There's still more. You'll be challenged by your hamstrings, quads, outer hips, inner thighs, and erector spinae, says Mansour. Lastly, the first four movements-which involved laying on your back and holding your hips up in a bridge position-work many of the smaller stabilizing muscles in your inner thighs, core and back, says Mansour.

This is especially great because in more traditional lower-body moves, like squats or lunge, it's easy to rely on your bigger, powerhouse muscles (like your quads, glutes, and hamstrings). But with the moves in this workout, because you are often in unstable positions, you'll work. "It's impossible to do these moves without activating those smaller muscles," explains Mansour. Strengthening these smaller muscles is important because it will help you better support your joints and control your movements during exercise.

Strength in your glutes and the surrounding muscles is important for a number of reasons.

Your gluteus maximus is the largest muscle in your body. Having a strong glute, max, glute, and glute, minimus, and strong muscles around your glutes helps support your lower back, promotes good posture, stabilizes your legs, and maintains the integrity of movement in your hip joint, says Mansour. It also helps your inner thigh and outer hips become more stable, which will rise, walk, run, and perform other day-to-day movements, she says.

This circuit will improve your hip mobility.

Two of the moves in particular-tables slides and side kicks-will work your hip mobility, says Mansour. These moves involve getting on all fours and externally rotating your hip. "As you turn away from the hip in these moves, you'll increase the mobility of your hip," she explains.

Here's how to do the eight-part circuit.

Grab a mat or find a comfortable spot on the carpet. Do each move one after another, and then repeat the entire circuit two more times (for a total of three) .

For each exercise, there is a suggested number of reps, but you should only do as many as you can with good form. It's totally fine to start with fewer reps and work your way up as you get comfortable with the movements and build strength.

Single-Leg Bridges

  • Lie faceup with your knees bent and feet flat on the floor , hip-distance apart, arms extended on the ground by your sides. Your heels should be just a few inches away from your butt.
  • Brace your core so that your back is flat against the floor.
  • Lift your left leg straight up in the air.
  • Keeping your leg lifted and straight, using your glutes, hamstrings, and core to lift your hips. Try to create one diagonal line from your shoulders to your knees.
  • Pause for a moment at the top of the movement and then lower your hips back down.
  • This is 1 rep. Do 20 reps.
  • Switch legs and do another 20 reps with your right leg lifted.

This move is great for your hamstrings, says Oprea.

As you do the reps, focus on those muscles groups and remember this is not an arm or upper-back exercise, says Mansour. “Even though your arms are touching the ground, they should not be engaged. This is all lower-body and core work.”

Your grounded leg may shake as you lift your hips, and that's OK. The higher you lift, the more challenging this move will be, so, Mansour. You can also begin with, you can also find the best way to start this work. Startner-friendly, she adds.

Double-Leg Bridges

  • Stay on your back, on your floor, on the floor, on the floor, on the floor. hips. Try to create one diagonal line from your shoulders to your knees.
  • Brace your core so that your back is flat against the floor.
  • Press through your heels and use your glutes, hamstrings, and core to lift your hips. Try to create one diagonal line from your shoulders to your knees.
  • Pause at the top of the movement and squeeze your glutes, and then lower your hips back down to the starting position.
  • This is 1 rep. Do 30 reps.

This move is all about the extra glute squeeze at the top, says Mansour. "It's easy to lower your hips down and bring them back up, but the [focus] should be on that top part." These double-leg bridges are priming your muscles for the next move, she adds.

Cheek to Cheek Bridges

  • Get in the starting position described above.
  • Press down through both heels and squeeze just the right side of your glutes to raise your hips several inches; pause at the top of the movement and squeeze your right side again, and then lower your hips back down to the starting position.
  • Press down through both heels again and this time, squeeze just the left side of your glutes to raise your hips several inches; pause at the top of the movement and squeeze your left side again, and then lower your hips back to the starting position.
  • This is 1 rep. Do 20 reps.

As you do these side-to-side pulses, make sure that your knees don’t open wider than your hips and that your hips stay even and don’t “dip down too much or torque upward too much,” says Mansour. You can do this by engaging your inner thighs.

Wide Pulses

  • Stay on your back and open your feet up several inches wider than your hips. Your toes and knees should be angled slightly, and your knees should be over your toes.
  • Squeeze your glutes and lift your hips up. This is the starting position.
  • From here, pulse your knees out and in about 1 inch.
  • One pulse is 1 rep. Do 30 reps.

Be sure to keep your hips elevated throughout the movement, says Oprea. "You are not going up and down your shoulders."

These pulsing movements should stay small and controlled, adds Mansour. By doing so, you'll target your hamstrings, all your gluteal muscles, as well as yourselves, stabilizing muscles.

Butterfly Pulses

  • Flip over your stomach and, elbows pointing out, place one hand on the top of the other, and lower your head, putting your forehead on top of the back of your hands./108
  • Press your heels together and splay your knees out so that they are opened up wider than your hips. Your legs should be in a sort of diamond shape.
  • Brace your core and press your pubic bone into the floor.
  • Squeeze your glutes so that your thighs and knees raise off the ground. Once here, squeeze your glutes even more to lift your legs up and down in small, pulsing movements.
  • One pulses equals one rep. Do 20 reps.

Be sure to relax your upper body as you perform the pulses. “Your head, neck, and shoulders [should] not help you on this,” says Oprea. Instead, focus on pulling your quads off the floor and keeping them lifted while you perform the pulses. You should feel the work in both your gluts and hamstrings.

The higher you lift your legs off the ground, the more difficult this will be. If you are a beginner, start with smaller lifts than Oprea demos, recommends Mansour.

Table Slides

  • Start on all fours with your shoulders stacked over your wrists, your fingers spread wide, and your knees hip -width apart.
  • Squeeze your abs and glutes to lift your left leg, knee bent, out to the side and to the hip level. This is the starting position.
  • From here, straighten your left leg as you press it, back to the wall behind you, and up. Pause for a moment when it's fully straightened and then bend your knee to bring it back to the starting position./ 11/9 Shaving legs and do 20 reps with your right leg.
  • This is 1 rep. Do 20 reps.
  • Switch legs and do 20 reps with your right leg.

The key here is to keep your knee lifted the entire time, says Oprea. As you do the movements, keep your toe pointed and your glutes squeezed. “Don’t just fling your leg back and forth,” she adds. The movements should be slow and steady.

This will also work your hip mobility, says Mansour. As you straighten your leg back and up, "it may feel like a stretch."

Try to keep your hips as centered as possible throughout, says Mansour. It will be easy for your hips to sway towards the leg that's grounded, but try to use your inner thighs and core to pull them back to the center, she says.

Lastly, this single-leg move relies on your arms and shoulders for stability. If you have any shoulder and/or wrist issues, try doing this move on your forearms instead, says Mansour.

Side Kicks
  • Get in the all-fours starting position described above for the table slides.
  • From here, straighten your leg directly out to the side. Pause for a moment, when it's fully straightened, and then bend your knee to bring it back to the starting position.
  • This is 1 rep. Do 20 reps.
  • Switch legs and do 20 reps with your right leg.

As with the table slides, your knee should be elevated the entire time. “Don’t let it drop,” says Oprea. This will be challenging and will fatigue the outer hip muscles, says Mansour.

Jumping Jacks or Jump Rope

  • Do jumping jacks or jump rope for 1 minute.

This cardio component is active recovery for your glutes before the next round, says Oprea.

Repeat the circuit two more times, for a total of three.