Which one should you choose – planks or crunches? Let’s talk about the differences between the two exercises and look at each one in more depth.
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Are planks better than crunches?
Planks and crunches work your rectus abdominals and oblique muscles, but the plank also works your transverse abdominals in addition to your upper and lower body muscles, meaning, the plank is a much more effective exercise that is better for building overall core strength when compared to crunches.
Crunches aren’t all bad though, if you’re looking to specifically target the rectus abdominals, then crunches are more effective as they isolate that muscle, in addition to working the obliques somewhat.
What are planks?
Planks require you to hold your body in one position (i.e. a position similar to the start of a push-up) for a certain amount of time, which works your entire core, in addition to your upper and lower body muscles.
Plank technique
Here is a step-by-step guide on how to do the most common type of plank, the forearm plank:
- Start in the press-up position, with your feet hip-width apart. Then, bend at your elbows so that you place your forearms on the ground, with your elbows directly under your shoulders.
- Press you’re forearms and toes into the ground, keeping your legs relatively straight and squeezing your abs, back and glutes, so that your body is held in a straight line – this is your plank position.
- Hold this position for the time recommended by the coach, and/or until you can no longer hold the correct position.
Side note: a common mistake is either letting the hips drop or raising your bum too high. We recommend doing your plank side-on into a mirror so that you can check that your body is flat, just like a plank of wood! If your hips start to drop, it’s an indication that you need to squeeze your glutes and core muscles more or you’ve reached your physical limit (we call this, going to technical failure).
Plank exercises muscles worked
The plank works your entire core, including the following main muscles:
- Transverse abdominals – these muscles are the deepest muscles within your abdomen, so they are sometimes called “the inner abs.” They “wrap” around the front and side of your abdomen between the bottom of your ribs and top of your pelvis. They’re responsible for protecting and holding your internal organs in place as well as providing stability for the lower back and pelvis.
- Rectus abdominals – this muscle runs vertically along the front of your abdomen and is responsible for flexeing (bending) your trunk.
- External obliques – these muscles are called “the obliques” and are the outermost muscles on the sides of your abdomen. They are responsible for bending the trunk side-ways, forwards and backwards as well as rotating.
- Internal obliques – these muscles are also called “the obliques” and lie between the transverse abdominals and external obliques. Like the external obliques, they are responsible for bending the trunk side-ways, forwards and backwards as well as rotating.
Planks don’t just strengthen your core, they also work your upper body muscles (trapezius, rhomboids, pectorals, serratus anterior, latissimus dorsi, triceps and biceps), as well as your lower body muscles (quadriceps, glutes, hamstrings and calf muscles). This is because you’re balancing your weight on your arms and toes, so your whole body must work to hold you in position.
What are crunches?
Crunches, also known as abdominal crunches, are a dynamic and repetitive core exercise, that requires you to “crunch” your top abs into your bottom abs whilst laying on your back for a certain number of repetitions, which only works some of your abdominal muscles.
Crunch technique
Here is a step-by-step guide on how to do a crunch:
- Lie on your back on the floor, and bend your knees so that your feet are flat on the floor and shoulder-width apart.
- Cross your hands over your chest – you may see some people placing their fingertips on either side of their head, we recommend avoiding this so that you don’t put strain on your neck when sitting up).
- Squeeze at your core and lift your shoulders off the ground and “crunch” your top abs into your bottom abs, whilst making sure your lower and mid-back don’t come off the floor.
- Reverse this movement by lowering your shoulders back to the floor.
- You’ve completed one repetition. Repeat this process for the number of repetitions your coach has recommended.
Side note: keep your feet flat on the floor throughout the whole lift. If you can’t do this, we recommend working towards being able to do that through other core strength exercises. In the meantime, either pick a different exercise or a partner can hold your feet flat on the floor or you can place your toes under a bar to help your feet stay on the floor.
Ab crunches muscles worked
The crunch is an isolated abdominal exercise that mainly works your rectus abdominals and oblique muscles to an extent.
- Rectus abdominals – this muscle runs vertically along the front of your abdomen and is responsible for flexing (bending) your trunk.
- External obliques – these muscles are called “the obliques” and are the outermost muscles on the sides of your abdomen. They are responsible for bending the trunk side-ways, forwards and backwards as well as rotating.
- Internal obliques – these muscles are also called “the obliques” and lie between the transverse abdominals and external obliques. Like the external obliques, they are responsible for bending the trunk side-ways, forwards and backwards as well as rotating.
Unlike the plank which works the upper and lower body, those are the only muscles the crunches work.
Are planks as effective as crunches?
Planks are more effective than crunches at building overall core strength but not as effective as crunches if you only want to target your rectus abdominal muscles.
Summary
The plank requires you to hold your body in one position (i.e. a position similar to the start of a push-up), which works your entire core equally, your upper body and lower body, whereas the crunch is a dynamic exercise where you repetitively move between lying with your back on the floor and lifting your shoulder off the floor, which mainly only works the rectus abdominal and oblique muscles.
If you would like to compare planks to other core exercises, check our out article on planks vs sit-ups. Or for more insight into ab exercises read our sit up vs crunches article.
