What Muscle Does a Plank Work?

The plank is a fantastic way to build core strength and endurance. In this guide, we dive into detail about all things plank. We’re going to cover:

Let’s jump right into it…

Plank Muscles Worked Diagram

Plank Muscles Worked Explained

The plank mainly works four muscle groups, your rectus abdominus, transverse abdominus, internal obliques and external obliques.

Your Rectus Abdominus: Your rectus abdominus or ‘six-pack abs’ are one of the main muscles worked during a plank. Typically, these muscles are used to flex the spine (e.g. in a sit-up) whereas in the plank they are used to resist extension of the spine.

Your Transverse Abdominus: Your transverse abdominus are your deeper core muscles responsible for stabilisation of your torso, as well as maintaining good daily posture. Your transverse abdominus works in the plank to hold you stable and braced.

Your Internal Obliques: Located more towards the side of your abdomen, your internal obliques assist with hip and back stability during the plank, keeping your body level.

Your External Obliques: Your external obliques are located a layer above your internal obliques. During a plank, they work to provide hip and back stability, as well as helping to resist spine extension.

What about traps, rhomboids, biceps, triceps etc?: Some people say that planks also work your rhomboid, bicep, tricep and trap muscles. This is technically true, but to such a minor extent that it barely counts. Let’s put it this way, no one in the history of physical training has built these muscles to be strong or impressive looking using planks.

What Are Your Plank Agonist and Antagonist Muscles?

• Your agonist muscles in the plank are your rectus abdominus, transverse abdominus and obliques.
• Your antagonist muscles are your erector spinae, lower back muscles, and to a lesser degree your traps and rhomboids

How to Plank Correctly

As a coach, I wish more people would stop and ask “how do I do a plank?” because far too many people assume that they know how to do them, and end up planking incorrectly.

Getting the core strength, stability and endurance benefits of the plank requires good execution of the movement. Here’s how to plank correctly.

1) Arrange your body in a straight line with feet close together and elbows firmly planted on the floor.

2) Start your plank by finding a nearly horizontal body position, with your hips not too low and not too high.

3) Aim to protract (roll forwards) your shoulders. Essentially you’re doing the opposite of squeezing your shoulder blades together.

4) Make sure that you maintain a tucked pelvis, with squeezed glutes. Don’t allow your lower back to extend/arch towards the ground, or the movement won’t actually be training the muscles you intended.

Plank Exercise Variations for Core

Plank on Knees

The plank on knees is a great plank variation for beginners that reduces what we call the ‘lever length,’ i.e. knees to shoulders is less distance than toes to shoulders, so you have to support less bodyweight. Here’s a good demonstration by the team at girls gone strong.

Plank on knees muscles worked

The plank on knees still works the rectus abdominus, transverse abdominus, internal and external obliques. The main difference is that it works these muscles with less intensity.

Straight Arm Plank

The straight arm plank is a plank variation in which you use straight arms and place your weight on your hands rather than your forearms. It places your body at a slightly different angle and is a good first step in learning a proper push-up.

Straight arm plank muscles worked

The straight arm plank works the same muscles as the plank on forearms. Due to the angle, some people find it a little easier, whilst others find it harder on their shoulders and wrists. I recommend trying both variations to see which you prefer.

Best Plank Alternatives

The plank is a good exercise for your core, but what if you can’t seem to get it quite right? Or perhaps you want to add some variety to your training? Here are two plank alternatives for you to try.

Deadbugs

The deadbug is one of my most prescribed core exercises. It is a great way to train to keep your core stiff and stable whilst your arms and/or legs are moving. It’s also a good exercise for teaching you to keep your butt tucked, which you can do by making sure there’s no gap between your back and the ground.

Deadbug muscles worked

The deadbug works your rectus abdominus, transverse abdominus, internal and external obliques. If you just move your arms or leg on their own, it works these muscles less, if you move your arms and legs at the same time, the deadbug works these muscles much more.

Hollow Holds (Dish Holds)

The hollow hold is a core exercise commonly used in gymnastics. To perform the exercise you lay on your back and then lift your arms, shoulders and legs off the floor by about 30 degrees, creating a ‘dish’ shape if viewed from the side.

Hollow hold muscles worked

Hollow holds (dish holds) still work your rectus abdominus, transverse abdominus, internal and external obliques. The main difference is that hollow holds tend to be more intense, working these muscles harder.

Plank Programme

Looking for a simple and effective plank programme to increase your core strength and core endurance? Here’s a plank programme I’ve put together for you to try…

Progression on the plank programme

Progressive overload comes each week through adding sets and/or time which is great for building muscular endurance in your core.

Day 1 is focuses on doing more total planking time, whilst day 2 focuses on building the plank itself.

If the programme looks too easy, you can either increase the times or swap the exercises for more challenging variations.

Looking for a Full Body Bodybuilding Programme?

Core work is great, but ideally, it should be part of a well-rounded training programme.

I’ve put together a 17-week hypertrophy programme.

It’s an evidence-based programme designed to add size to your entire body.

Plus, it comes with specific guidance so that you can adjust your amount of training each week to suit your recovery.

You can find out more about the programme here.

Plank Benefits – What Makes the Plank So Special?

The plank is one of the most popular exercises in gyms and fitness centres around the world, but why is it so popular? Here are 3 major benefits of the plank:

1. Planks teach you to resist movement: Lots of classic ab exercises involve crunching and flexing, which is good for muscle building, but core function for most sports is far more about stiffness and resisting movement. The plank allows you to train this quality.
2. Planks are easy to teach and learn: Exercises like hanging leg raises require special equipment, whilst exercises like candlesticks, dragonflags etc can be difficult to teach and learn. The plank is simple, requires no equipment, and you can learn it in 2 minutes.
3. Planks are lower back friendly: Whilst crunching and sit-up type exercises put loads of compression forces through the lower back, planks create far less compression force. This makes them much safer for your spine, and a great choice for anyone dealing with lower back injuries

What Muscle Does A Plank Work: Frequently Asked Questions

Does plank build muscle?

Yes, planks build muscle in your rectus abdominus, transverse abdominus, internal and external obliques. However, if you’re looking to maximise the amount of size you add to your six-pack abs, you might also want to add some flexion-type movements like crunches.

What muscles do a side plank work?

Side planks mainly work your internal and external obliques.

Are planks actually effective? And do planks give you abs?

Planks are an effective way to build core strength and core endurance, which can improve sports performance and reduce injury risk. They can also be used to build muscle, including your rectus abdominus or ‘six pack’ abs.

Is plank necessary?

You don’t have to plank if you don’t want to. There are plenty of other core exercises that you can use such as dead bugs and hollow hold progressions that will have a similar training effect.

How many planks should I do?

I recommend doing between 2 to 6 sets of plank, holding each set only for as long as you can with perfect technique. So if you can only hold a plank for 20s with perfect form, then stop your set at 20s. You can then add more sets and build up your training that way.

How often should I plank?

I recommend planking 2 to 3 times per week. For example, you could perform 2 sets of plank on Monday, Wednesday and Friday for a total of 6 sets per week.

Next Steps

Alright, that’s enough reading for today, time for action…

1) Get in the gym and start practising your planks, maybe even run through my 4-week plank programme. Build more core strength and endurance. Improve performance and reduce injury risk.

2) If you want more training tips, workouts and programmes, feel free to join my mailing list.

3) And if you’re looking for 1:1 strength and conditioning coaching, you can find more information about my services here.

‘Til Next Time

Alex

Alex Parry, MSc, BA

Alex’s experience includes 8+ years within strength & conditioning, including supporting 2 major universities, 2 national talent pathways and a selection of international level athletes.

He is also a tutor and educator for British Weightlifting

References

Axler, C. T., & McGill, S. M. (1997). Low back loads over a variety of abdominal exercises: searching for the safest abdominal challenge. Medicine and science in sports and exercise, 29(6), 804–811. https://doi.org/10.1097/00005768-199706000-00011

Sutanto, D., Ho, R., Poon, E., Yang, Y., & Wong, S. (2022). Effects of Different Trunk Training Methods for Chronic Low Back Pain: A Meta-Analysis. International journal of environmental research and public health, 19(5), 2863. https://doi.org/10.3390/ijerph19052863