Sit-ups: How to do them with proper form and why it matters

Woman in the gym performing a sit-up with hands behind head on exercise mat
(Image credit: Shutterstock)

If you're unsure how to do a sit-up, we've got the answers to help you maximize this popular exercise. When you think of some of the best ab workouts, the sit-up is a classic, and the exercise can provide plenty of benefits for your midsection. 

The muscles that make up your core aren’t there just to look good. Strong abdominal muscles are important for your posture, for day to day activities, and can support your body as you perform exercises like squats or deadlifts. 

Sit-ups target a number of muscles in the core, not just the rectus abdominis, also known as the ‘six-pack’ muscles. The move also works the obliques; the muscles that run down the side of our core, and the transverse abdominis; the deep abdominal muscles that wrap around our spine for extra stability. And sit-ups also fire up the hip flexors which help to flex your knee up towards your body.

However, when done incorrectly, sit-ups can cause pain and injury, particularly in the lower back. Because of this, it’s important to learn how to do a sit-up properly. Here's how. 

How to do a sit-up

A basic sit-up is fairly simple, but before you start, make sure you have a comfortable exercise mat or floor space. We’ve hand-picked the best yoga mats on the market if you are looking for an exercise mat for your home workouts.

  • Lie on your back with knees bent and feet firmly on the ground
  • Place your hands behind your head, or place each hand on the opposite shoulder, so arms cross over the front of your body, whichever feels more comfortable to you 
  • Slowly lift your upper body off the ground, keeping your chin tucked into your chest
  • Lift your body up towards your thighs, so you're sitting upright
  • Pause, then slowly lower your body back to the start position
  • You may find that you struggle to keep your feet firmly planted into the ground, so recruiting the help of a friend to hold your feet down, or placing feet under weights, can be helpful.

Sit-ups vs crunches — which is better?

In the sit-ups vs crunches debate, which is better?

Sit-ups and crunches are both targeting the same muscles — the main difference between the two exercises is the range of motion. With a sit-up, you move your torso to a sitting position, whereas in a crunch, you only lift slightly off the ground to raise your upper back.

When it comes to which is best, it depends on your goals. Sit-ups are more challenging than crunches, as you lift higher off the ground, but if you suffer from back or neck issues or are a beginner, it might be safer to opt for crunches. However, some people struggle with their lower back during crunches, so it's best to see what works for you and opt for other ab exercises if they both hurt your lower back. 

How can you make sit-ups harder or easier?

If you’re keen to take your sit-up to the next level, try incorporating some resistance. 

Weighted sit-up: 

A weighted sit-up involves holding a weight close to your chest or overhead and taking it up with you as you curl your body towards your knees. We’ve found the best adjustable dumbbells for home workouts here. 

Adding resistance works the muscles a little harder, helping to build more strength. It’s important to remember that a weighted sit-up places far more pressure on the back, so only add weight when you've mastered the basic sit-up.


To make a basic sit-up easier, opt for a crunch. Lie on your back, again with knees bent and feet flat on the floor. Place your arms in the same position as you would with a sit-up, but instead of curling your spine and coming up to sitting, just bend slightly until you feel a ‘crunch’ in the abdominals, then lower back down. A crunch will focus more on the rectus abdominis muscles, and after several crunches, you’ll certainly feel a burn in your stomach muscles.

Often, people find that sit-ups can be a little painful on their tailbone. If this is you, try doing your sit-up on a large, inflatable stability ball. These are far softer on the tailbone; plus as the ball can move around so easily, it helps with balance, firing up the core even more as it works to stop you from rolling off the ball.

Reverse crunch: A little variation on the crunch, and a slight backward style of a sit-up, is the reverse crunch. For this lie on your back, with feet off the floor and knees at a right angle. With arms on either side of your body, lift your glutes off the floor so that your knees come closer to your face. Then lower back down. Here’s more on how to do a reverse crunch with the correct form. 

The benefits of a sit-up

There are plenty of benefits to a sit-up when it’s done properly.

Working to strengthen the core muscles is important for so many aspects of life. From getting out of bed in the morning to carrying the groceries and closing the car door, all these require your core muscles.

Plus, other exercises can benefit from stronger core muscles too. Take running for example: your core is needed as you power your body forward. When you sprint, a strong core holds you upright as you pump your arms and drive to the finish line. Weight lifting also requires core strength; if your core isn’t fired up when you’re squatting, for example, it can lead to an arched spine, and in time, injury.

One of the benefits of a sit-up is that it activates and strengthens several of these core muscles, which can help with stability, posture, and balance and reduce your chance of pain.

When the core muscles are weak, other muscles in the body have to overcompensate. This includes muscles in the back and lower body. If muscles have to overcompensate for other, weaker muscles, it can result in injury as they end up tight and overworked. 

Building and working on muscle strength is especially important for women as they age. When women go through menopause, hormonal changes can cause muscles and bones to weaken. Resistance-based exercise, whether bodyweight or using weights, can help avoid this. One study on 93 older women found that those who could perform sit-ups had less chance of lower muscle mass (also known as sarcopenia). 

Sit-ups also work the spine and can help with mobility and flexibility. If you’re someone who struggles with flexibility, you may find sit-ups a struggle at first as they require you to sit fully upright. However, as with anything, the more you practice, the easier it can become!

Maintaining flexibility is important whatever age you are. Why? Staying flexible not only reduces injury, but research has found it can help with every single movement you do in a day, while also helping you relax and sleep.

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Lucy Gornall

Lucy is a freelance health and fitness journalist as well as a pre and post-natal personal trainer. Although a sweaty gym session (skipping rope is a must) is her favorite way to ‘relax’, she’s also a fan of bingeing on The Office, snacking on chocolate-coated raisins, and fizz-filled brunches with friends. 

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