A basic plank is a great core exercise. But Nashville-based celebrity trainer Erin Oprea, who works with Carrie Underwood, Kelsea Ballerini, and Martina McBride, among others, has taken it one step further—well, four steps, to be exact—and turned this go-to total-body move into a challenging workout.
Oprea posted an Instagram video on Sunday via @erinoprea in which she demos a four-part plank series that looks especially excruciating (in all the best ways, of course).
You can check out the video here:
“It was rainy and nasty outside, and I wanted to work my obliques really hard and hit them from different angles,” Oprea tells SELF about the inspiration behind this sequence.
The circuit hones in on the obliques, which are the muscles that run along the sides of your stomach.
“Oblique strength is as important as overall core strength,” says Oprea. That’s because the core, which is essential for powering us through daily movements and workouts alike, is composed of more than 20 different muscles, and it relies on the strength of each muscle to work efficiently and effectively as a unit. That said, many core exercises focus on the rectus abdominis (what you think of as your abs) and not as much on your obliques, which help you bend to one side and perform any type of twisting motion. Just like your other core muscles, your obliques play an important role in your overall core strength and stability, which is why it’s important to do exercises like these plank variations that strengthen them.
Oprea’s particular plank sequence is designed to “burn out the obliques,” she says. That means each exercise targets the obliques, and when performed together with no rest in between, they’re intended to work your obliques to exhaustion.
But these four moves aren’t just about the obliques.
They also work your core as a whole, as well as major muscles in both your upper half and lower half.
“Planks work your core all the way around,” says Oprea. “They get your lower back, which is part of your core, as well as your arms, butt, and legs [in particular, the quads].” The plank is a great example of a compound exercise, or a move that engages multiple major muscles groups at once to give you a total-body workout.
With this sequence, you’ll also work your shoulders, Oprea adds. Essentially, this plank circuit is a great tool for building total-body strength and stability.
Here’s how to do the sequence:Side Plank Twist
- Start in a side plank, resting on one forearm with your body in a straight line. Make sure your elbow is stacked directly under your shoulder. Your hand should be in front of you.
- Stack your top foot above the bottom (as Oprea demos). Or, to make the move easier, stagger your top foot on the floor in front of your bottom foot.
- Bend your top elbow and place your hand behind your head. Squeeze your core and keep your hips elevated. This is the starting position.
- Squeezing your obliques, rotate your entire trunk in until your bent elbow hovers just a couple inches off the floor. Continue squeezing your obliques to rotate your entire trunk back to start.
- Repeat for 15 to 30 seconds before going immediately into the next move.
Before you begin performing these twists, make sure to lift your hips up and really squeeze your obliques on the side closest to the floor. As you twist, focus on continually squeezing this area. “It’s not just going through the motions,” says Oprea. “Your mind has to focus on the muscle group you're trying to move.” Throughout the movements, make sure that your elbows and shoulders stay in one line, she says.
Side Plank Pulse
- Stay in the side plank position described above, but instead of bending your top arm behind your head, extend it above, reaching toward the ceiling. This is the starting position.
- Squeeze your core to lift your entire trunk several inches and then slowly lower it back to start. Keep your core engaged the entire time.
- Repeat these pulses for 15 to 30 seconds before going immediately into the next move.
As with the prior variation, focus on continually engaging your obliques as you perform this move, says Oprea.
Plank Hip Dip
- Get in a forearm plank with your feet slightly wider than hip-width apart, your elbows under your shoulders, and your core, glutes, and quads engaged.
- Keeping your entire upper body as still as possible, rotate at the hips and swivel your feet slightly to rock your lower half from side to side.
- Repeat for 30 seconds before moving immediately into the next move.
This variation works your obliques (yet again), but is more targeted for the overall core, says Oprea. The side-to-side rocking should be driven from your hips, and your feet should (just barely) move along with them. Squeeze your core, glutes, and quads before you begin rocking—and continue squeezing them throughout.
Plank Knee Twist
- Stay in the forearm plank position described above.
- Lift your right leg, bend at the knee, and rotate your core to drive your knee in toward your left elbow.
- Bring your right knee back and straighten the leg to return to the starting position.
- Repeat with your left leg, rotating your entire core to bring your left knee to your right elbow. Bring the knee back and straighten your leg to return to start.
- Continue, alternating legs, for 30 seconds.
As you perform these twists, your butt will naturally want to drift up. Don’t let it, says Oprea. “Make sure your back, your booty, and your legs stay in one nice line.”
Once you’ve completed the entire sequence, rest for one to two minutes and then repeat the sequence again.
The second time through, do the first two moves on the opposite side.
And just a few more form notes to keep in mind:
With each of these four variations, and with planks in general, the key is to keep your hips elevated by squeezing your glutes and quads, and focus on really engaging your core by thinking about pulling your belly button in toward your spine. “You should start shaking because you are tucking so tight,” says Oprea.
You shouldn’t feel any pain or strain in your lumbar spine (aka lower back) as you do these moves. If you do, that’s a sign that your core isn’t fully engaged and your back is stepping in to bear some of burden, explains Oprea. This can result in undue stress being placed on your spine, which, over time, could lead to back pain or even an injury. Again, think about pulling your belly button in toward your spine and tuck your hips under a bit. If you do that and still feel stress in your lumbar spine, consider regressing the move by either putting both feet on the ground (if you’re in the side plank) or both knees on the ground (if you’re in the forearm plank).
Do whatever is best for you and your level of fitness, says Oprea. “It’s better to be on your knees and have perfect form than to be up on your toes without good form.” And her last bit of advice? "Have fun with this," she says. "Don't think of planking as a dreaded thing. Put on good music, grab a workout buddy, and enjoy."