Planks Vs Sit-Ups – Your Ultimate Guide

Planks and sit up’s are great exercises to strengthen your core muscles, but which exercise is best? Below, we’re going to talk you through the differences between the two exercises and why one may be better suited than the other.

Planks vs sit-ups

Planks require 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 in addition to your upper and lower body, whereas the sit-up is a dynamic exercise where you repetitively move between lying down and sitting up, whilst on the floor, which mainly works your core and hip flexors.

You typically hold a plank for a certain amount of time, whereas you can do sit-ups for either a certain amount of time or a certain number of repetitions. 

Whether you choose to do planks or sit-ups, core strength is important for good posture, balance, reducing back pain, and provides you with a solid foundation as an athlete!

Joints worked and ranges of motion

To understand the difference, firstly we must understand what joints and muscles are being used.

JointMovementPlanks ROMSit Ups ROM
HipsFlexion/ExtensionNoneMedium – High
Lumbar spineFlexion/ExtensionNoneMinimal
Thoracic spineFlexion/ExtensionNoneMinimal – Low

Muscles worked during a plank

The plank works your entire core, including the following main muscles:

  • Rectus abdominals –  this muscle runs vertically along the front of your abdomen and is responsible for flexeing (bending) your trunk. 
  • 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. 
  • 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. 

Muscles worked during sit-ups

The main muscles worked during a sit-up include: 

  • Rectus abdominals – this muscle runs vertically along the front of your abdomen and is responsible for flexeing (bending) your trunk. 
  • 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.  
  • 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. 
  • Hip-flexor muscles (iliopsoas and rectus femoris) – these muscles are responsible for bending at your hip joint when you sit up. 

If you place your hands by your head when doing a sit-up, your neck, chest, and shoulder muscles will work when you lift your body off the floor. You can reduce this to an extent, by placing your hands across your chest. 

Plank technique

Here is a step-by-step guide on how to do the most common plank, the forearm plank: 

  1. 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. 
  1. 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.
  1. 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). 

Sit-up technique

Here is a step-by-step guide on how to do a sit-up:

  1. Lie on your back on the floor, and bend your knees so that your feet are flat on the floor and shoulder-width apart. 
  1. Cross your hands over your chest, or place your fingertips on either side of your head –  we recommend the first option so that you don’t put strain on your neck when sitting up).
  1. Squeeze at your core, and lift your chest off the floor. 
  1. Keep lifting your chest off the floor until you’re in an upright sitting posture, with your chest close to your knees. 
  1. Reverse this movement by lowering your chest back to the floor. 
  1. 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.

Common Question’s

Are planks better than sit-ups?

Planks and sit ups work similar muscles in the core, yet, the plank is typically considered the “superior” exercise. This is because the plank recruits the core muscles on the front, side and back off the trunk relatively equally whereas in the crunch which also recruits those muscles, it biases the rectus abdominals and hip flexor muscles. Another reason the plank is typically considered the “superior” exercise is because the sit-up can place strain on your lower back and hip flexors.

If you prefer sit-ups to planks, we recommend making sure your other core muscles are also being strengthened with complimentary exercises, such as resussian twists on the floor to target your obliques and transverse abdominals. 

What is better for abs plank or sit-ups?

It depends on which abdominal muscles you want to strengthen – if you mainly want to strengthen your rectus abdominals, then sit-ups are better, but if you want to strengthen your whole core, then the plank is better. 

When should I use each exercise?

If your short on time, the plank would be a good core exercise to do as you’ll work your whole core in one exercise.

If you have a bit more time or want to do a circuit, that might be a good time to do sit-ups to mainly target your rectus abdominals, but make sure you pick other complementary exercises to do in the circuit so that you work your other core muscles equally. 

Can I do sit ups and plank exercises?

Yes you can – if you choose to do both sit ups and the plank in one circuit, you are still over working the rectus abdominals, so we still recommend picking complementary exercises to target your transverse abdominals and internal and external obliques, so that you work all of your core muscles equally during the circuit.

How long should you hold a plank?

There is no set time on how long you should be able to hold a plank for, it very much depends on where you are in your physical development and the demands of the sport you play. With that said, we can follow some general principles based upon what you would like to achieve: 

Muscular endurance / robustness

If you play a sport where you repeatedly perform certain movements that require your core (for example, the rowing stroke repeatedly) or a sport where you must use your core muscles/hold positions for a relatively long period of time (for example, cycling), then hold the plank with your body weight only, and progressively increase the time that you hold the plank for. 

Strength 

If you play a sport where you have to create, transfer or absorb a great amount of force through the core, (for example, kicking or being kicked in taekwondo), then core strength is important to develop. This is typically developed by holding a plank for a short amount of time, with a plate placed upon your back, and progresivley increasing the amount of weight on your back in small increments. It’s important to highlight that you must maintain the correct technique and have a baseline level of strength in your core before building strength in this way. 

Important note: These are only general principles only, we recommend seeking professional advice that is specific to you from a strength and conditioning coach.

How many crunches should I do?

Our answer is similar to above – there is no set number of sit ups you should be able to do, it very much depends on where you are in your physical development and the demands of the sport you play. With that said, we can follow some general principles based upon what you would like to achieve: 

Muscular endurance / robustness

If you play a sport where you repeatedly perform certain movements that require your core (for example, the rowing stroke repeatedly) or a sport where you must use your core muscles/hold positions for a relatively long period of time (for example, cycling), then perform sit-ups with your body weight only, and progressively increase the number of repetitions you do. But make sure you do the same with other complementary exercises so that you work your other core muscles equally. 

Strength 

If you play a sport where you have to create, transfer or absorb a great amount of force through the core, (for example, kicking or being kicked in taekwondo), then core strength is important to develop. I’d argue that sit-ups probably aren’t the most effective way to build strength, planks might be better a better option. 

Important note: These are only general principles only, we recommend seeking professional advice that is specific to you from a strength and conditioning coach.

Sit ups vs crunches vs planks

Planks require you to hold your body in one position whereas both sit-ups and crunches are repetitive dynamic exercises. If you want to learn more about crunches, keep an eye out for our article crunches vs sit ups

Summary

Planks require 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, whereas the sit-up is a dynamic exercise where you repetitively move between lying down and sitting up, whilst on the floor, which also works your whole core but biases one part of your core, the rectus abdominal muscles.

If your short on time, the plank is a good exercise to do to strength your whole core in one exercise. If you have a bit more time or want to do a circuit, that might be a good time to do sit-ups to target your rectus abdominals, but make sure you pick other complementary exercises to do in the circuit so that you work your other core muscles equally. 

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