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What Muscles Do Planks Work? Plank Workout Muscles Explained

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I have been a certified personal trainer for 16 years and have worked with a host of clients with different backgrounds, body types, fitness levels, fitness goals, and ages.

Although all of these various differences, of course, inherently dictate very different workout programming, planks are one of the exercises that almost everyone can benefit from.

Planks are more effective and safer for most people than what we once thought were more “beginner-friendly core exercises” like crunches and sit-ups, and with all of the different ways to modify or progress planks, plank workouts can be scaled for all fitness levels.

But, what muscles do planks work? In this planks muscles worked exercise guide, we will discuss how to perform planks and the muscles worked by common types of planks for abs exercises.

We will look at: 

  • How Do You Do a Plank?
  • What Muscles Do Planks Work?
  • What Muscles Do Side Planks Work?
  • Do Planks Give You Abs?

Let’s jump in!

Two people doing forearm planks.

How Do You Do a Plank?

Before we look at the muscles worked by planks, let’s cover how to do a plank.

There are many variations of planks that can be progressed or plank modifications for beginners, but the two basic forms of the plank exercise are the forearm plank and the high plank.

The forearm plank exercise is the classic core-strengthening plank we tend to think of where your elbows are down on the ground. 

The high plank still targets many of the same plank muscle groups but it is performed in the top position of a push-up, so the muscles worked by planks in the high plank position are going to be different.

An elbow plank.

Elbow Plank

Here is how to do a plank on your forearms:

  1. Get into a push-up position, but drop down so that your forearms are on the floor with your elbows directly underneath your shoulders, and interlace your hands together under your face so that they meet in the middle.
  2. Your toes should be curled under as they are in a push-up position but your elbows will be on the floor. Your body should be in a straight line from the back of your head to the back of your heels as if you are one stiff board or plank. Do not stick your butt up into the air or allow your butt to sag down.
  3. Think about sucking in your belly button towards your spine to engage your abs while making sure that you are breathing steadily and normally throughout the exercise.
  4. Keep your head in a neutral position by staring straight down at your hands underneath your face.
  5. Hold for 10 to 30 seconds, gradually increasing the length as your muscular endurance improves.
A high plank.

High Plank

Here is how to do a plank in the “high plank“ position, or a push-up position plank with your arms extended:

  1. Get in a push-up position with your body in a straight line from your heels to your head. Your wrists, elbows, and shoulders should all be stacked under one another and your fingers should be spread slightly with your hands pointing forward.
  2. Keep your core tight, as if drawing your belly button up to your spine throughout the duration of the hold. Your spine should be held in a neutral position so that your gaze is down to the ground under your head (don’t look at your feet or in front of your body; keep your head neutral).
  3. Squeeze your glutes and make sure that you keep a straight line from the back of your heels to the top of your head without hoisting your butt up into the air or allowing your hips to sag down and create a sway back.
  4. Hold for 10 to 30 seconds, or the desired length of time, remembering to breathe throughout the entire exercise.
A person doing an elbow plank.

What Muscles Do Planks Work?

Planks are primarily an exercise for the abs, so they work the rectus abdominis, internal and external obliques, and transversus abdominis muscles.

The focus is mainly on the rectus abdominis, which is the central, “six-pack” abdominal muscle, and the transversus abdominis.

The abdominal muscles are part of the core, the collective group of muscles in the trunk that span from the diaphragm up top to the pelvic floor muscles on the bottom.

The core muscles include the abdominal muscles mentioned, as well as muscles of the back such as the erector spinae and multifidus muscle group. 

In addition to the abdominal muscles worked by planks, planks strengthen other muscles of the core such as the serratus anterior in the upper back and the latissimus dorsi.

Planks also work the glutes, pelvic floor muscles, and hip muscles, which can be thought of as an extension of the core.

Most plank exercise variations also work the deltoids in the shoulders and pectoralis major and minor in the chest as secondary muscle groups.

Like the standard forearm plank, the high plank strengthens all of the muscles of your core.

A group of people doing planks.

This includes the rectus abdominis, obliques, deep transversus abdominis, lower back extensors such as the erector spinae group and multifidus, your glutes, your pelvic floor muscles, as well as your shoulders and upper back muscles.

The primary difference between the muscles worked by planks in the forearm position and planks in the push-up position is that the high plank muscles worked involve more involvement from your shoulders, including the deltoids and rotator cuff muscles, as well as the muscles in your upper back.

All of the core muscles strengthened by planks are challenged to contract isometrically—creating tension without creating movement (shortening or lengthening to move a joint).

The obliques contract isometrically during planks to prevent lateral bending and rotation of your trunk as you hold the plank position.

Similarly, the deep transversus abdominis is one of the key muscles worked by planks. Contracting this muscle during planks helps to increase intra-abdominal pressure for spinal stability.

Good core strength is important for helping maintain proper posture, preventing low back pain and other injuries, improving movement mechanics, and optimizing athletic performance, whether running, cycling, hiking, or lifting weights in the gym.

Additionally, a strong core is important in injury prevention and for performing activities of daily living like lifting children, carrying groceries, climbing stairs, and putting things up on a high shelf.

For example, studies suggest that the benefits of a strong core include improving balance and stability, decreasing the risk of low back pain, improving lower limb function, and reducing the risk of sports or work-related injuries.

What Muscles Do Planks Work? Plank Workout Muscles Explained 1

What Muscles Do Side Planks Work?

The muscles worked by side planks include the same core muscles worked by forearm planks, but the emphasis shifts to the obliques.

Side planks involve an isometric contraction of your internal and external oblique muscles because more of the responsibility of supporting your spine and body weight is being concentrated on the obliques since you are positioned on your side.

Additionally, side plank muscles worked include more of the lateral deltoid or shoulder muscles on the supporting arm as well as the glutes, abductors, and adductors in the hips and thighs.

The side plank is slightly more challenging than a standard plank because you are decreasing your base of support from two arms and two feet to one arm and one foot.

A side plank.

Do Planks Give You Abs?

The plank is an effective core exercise because unlike crunches, sit-ups, and Superman back extension, the plank works the core muscles without putting a lot of compressive force on the lumbar spine.

This can make it safer.

That said, planks won’t give you abs.

“Getting abs” is a matter of losing enough body fat so that you can see muscle definition in your stomach.

Planks workout muscles certainly include your abs and core muscles, but doing planks for abs alone won’t sculpt six-pack abs.

Muscle definition comes down to your diet, overall body fat percentage, and building muscle with strength training exercises that use external resistance (such as cable crunches, kettlebell dead bug pullovers, medicine ball chops, and weighted planks).

A star plank.

Therefore, no matter how many plank workouts or other ab exercises you do, you’re not going to see any definition in your abs unless your body fat percentage is low enough.

Core-focused exercises performed properly and consistently can increase the size and strength of your rectus abdominis muscle (and each of those sections or “packs” in the six-pack).

However, if the layer of subcutaneous fat that lies on top of the muscles and underneath your skin is too thick, the striations and definition of the muscle will be concealed by the belly fat.

Once you lose enough fat, with proper training with effective core exercises like planks, you should begin to get the abs you’re striving for.

If you want to strengthen the muscles worked by planks, check out our 30-day abs workout challenge here.

A group of people doing a plank.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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