Whether you are a general gym-goer, a strength athlete, or looking to pass a fitness test, the sit-up is a popular marker for core fitness.
The problem is: you may not be able to do a single sit-up.
So why can’t you do a sit-up?
Here are 7 reasons why you aren’t able to do a sit-up:
- You have weak abdominal muscles
- You have weak hip flexor muscles
- You have a poor posture for a sit-up
- You may be too overweight
- You may have poor technique
- You may be currently or previously injured
- You lose balance when trying to fully sit up
In this article, I will break down exactly what we mean by a sit-up, reasons why you cannot do a single sit-up, and give you the exact solution for each of the potential reasons why you cannot do a sit-up.
Table of Contents
What Is A Full Sit Up?
A full sit-up requires you to start with your feet on the floor with your knees bent at around 90 degrees, and for you to start with your torso flat and relaxed on the floor. You then need to bring your whole torso off the ground until your back is fully off the ground and as upright as possible.
Your hands or fingers can be held by the side of your temple or your arms can be crossed with hands placed flat on the front of your shoulders. You must not grab the back off your head and/or pull your head when you execute the full sit-up as you can hurt your neck. You must also not pull against your shoulders or top when executing either.
A full sit-up should not be confused with an abdominal crunch which is a similar exercise that starts in a similar start position. The main differences between a full sit-up and a crunch is the range of motion and emphasis of the exercise execution.
A crunch requires curling your back and ribcage off the floor without necessarily lifting your lower back off the floor. Whereas a full sit-up requires your whole torso to come off the floor. A full sit-up does not necessarily need you to curl your back and can maintain a relatively flat posture.
A full sit up can be used as an exercise for the goal of improving core strength, endurance, muscle mass and fat loss. It can also be a fitness test as a market for core strength and endurance.
For testing, it may be performed as an AMRAP where you do as many reps as you can until failure or it can be performed within a certain time limit where you do as many as you can for a given time. Sit up tests can be used as a general fitness screening tool in gyms or in military based settings as well.
7 Reasons Why You Can't Do A Sit-Up
1. You Have Weak Abdominal Muscles
Your abdominal muscles, which are the six-pack muscles on the front of the belly, may be too weak to lift your upper torso off the ground. These are the first muscles that initiate when attempting to do a sit-up.
These abdominal muscles are going to be the main core or stomach muscles during the full sit-up exercise. If they are too weak, they will not be able to get your upper torso off the floor.
In order to fix this, you may need to use an alternative abdominal exercise to strengthen them until they get strong enough to help you do a sit up.
Example easier exercises that you can do to bring your abdominal strength before you do a sit up are:
Russian Twists
Planks
Reverse Crunches
Negative Sit Ups (downward only)
2. You Have Weak Hip Flexor Muscles
Your hip flexor muscles, which are located at the front of the pelvis, may be too weak to lift your lower torso off the ground. These muscles bring your torso and lower core area closer to your thighs.
The hip flexors are the muscles that get worked more in the full sit-up than in a crunch as it lifts your whole torso off the floor. If they are too weak, you may fail to fully complete the second half of the sit-up and bring your torso upright.
Training the hip flexor muscles can easily be trained with a variety of other exercises that target these muscles. For example:
3. You Have a Poor Posture for a Sit-Up
If you initially start the exercise with poor posture, you may be putting your muscles in a bad position for them to work. If you over arch your lower back so that when you are lying down and there is space between the floor and the lower back, then your abdominals are in a lengthened and weakened position for them to work.
To fix this you will need to make sure that your lower back is flat on the floor and there are a number of ways of cueing this.
One way you can do this is to tuck your pelvis under, or what is known as a posterior pelvic tilt. You can do this by squeezing your glute muscles and pushing your heels down on the ground.
Another way you can do this is to stretch your arms towards the sky and do a full exhalation until you can feel your abdominals and obliques engage. This will flatten your rib cage and lower your back towards the floor.
Related Article: 10 Best Side Crunch Alternatives (With Pictures)
4. You May Be Too Overweight
When you do a sit-up, you are lifting the mass of your torso off the ground so if you are too heavy, your core muscles may not be able to get you to sit up off the ground.
If you are overweight and/or unaccustomed to exercise, doing a sit up may be inherently very difficult. There may not be a short term fix to change this so that you can do a sit up but a long term fix.
You will need to use a combination of exercise and nutrition so that you are in a caloric deficit where you are consuming less than what your body needs to lose weight.
Exercise should include a combination of cardiovascular training and resistance training. The cardiovascular training will help you burn calories to lose weight and the resistance training will help with encouraging muscular fitness.
If you are unaccustomed to exercise, you should start with a full body approach with resistance training twice a week, and 75 to 150 minutes of aerobic activity a week.
5. You May Have Poor Technique
As with all exercise, good technique is important. If you have bad technique for the full sit-up, you can either put yourself in a disadvantaged uncomfortable position to execute it.
Bad technique may have elements of:
- Pulling your head up
- Grabbing your shoulders forward
- Starting with an over extended back
- Using momentum with your legs
- Sitting up with raising one side (right or left) higher than the other
Good technique will include the following qualities during a full sit-up:
- Starting with your back flat on the floor
- Keeping your feet firmly on the ground
- Keeping a mild contact of your heads to your head or shoulders
- Reaching as high as possible
- Sit up relatively symmetrically
6. You May Be Currently or Previously Injured
The full sit-up can put stress on your back and hip regions including the muscles and joints. If you have any pre-existing injuries in those regions you will need to ensure that they are fixed first.
With any injuries, depending on the nature, it will take time for it to heal or certain rehab exercises may be in order. It is important that you work with a relevant medical professional or physical therapist to address any pain or pathology before ensuing any exercise or fitness program.
Related Article: How To Do A Sit Up Without Lifting Your Feet? (5 Tips)
7. You Lose Balance When Trying To Fully Sit Up
Your legs need to ideally help you balance against your upper body during the sit up. Sometimes it may be that you are attempting to sit up too fast and you lose balance or that your torso is heavier than your legs.
If you are attempting to sit up too fast and your legs come up, then you can try one of two things. The first thing is to control the sit up execution speed. The second thing is to try and move your feet further away from you.
If you find that your legs are coming up and you keep falling back down when you sit up, a simple solution would be to perform an anchored sit up where there is an external support in keeping your feet down on the floor. You may use a weight or something else to keep your feet down.
Related Article: How To Do a Plank Correctly
How To Get Your First Sit Up in 4 Weeks or Less
To get your first sit up, you should build your way up by using a combination of using simpler abdominal exercises and slowly building up the work capacity of your core to be able to perform one.
Here is a simple 4 week core fitness program to building up to doing a sit up:
Week 1
Day 1
- 5 minute aerobic warm up
- Plank: 2 sets of 15 seconds
- Lying Leg Raise: 2 sets of 8 reps
Day 2
- 5 minute aerobic warm up
- Plank: 2 sets of 15 seconds
- Lying Leg Raise: 2 sets of 10 reps
Day 3
- 5 minute aerobic warm up
- Plank: 2 sets of 20 seconds
- Lying Leg Raise: 2 sets of 12 reps
Week 2
Day 1
- 5 minute aerobic warm up
- Plank: 2 sets of 20 seconds
- Lying Leg Raise: 2 sets of 12 reps
- Abdominal Crunch: 2 sets of 8 reps
Day 2
- 5 minute aerobic warm up
- Plank: 2 sets of 25 seconds
- Lying Leg Raise: 2 sets of 12 reps
- Abdominal Crunch: 2 sets of 10 reps
Day 3
- 5 minute aerobic warm up
- Plank: 2 sets of 25 seconds
- Lying Leg Raise: 2 sets of 12 reps
- Abdominal Crunch: 2 sets of 12 reps
Week 3
Day 1
- 5 minute aerobic warm up
- Plank: 2 sets of 30 seconds
- Russian Twist: 2 sets of 6 reps
- Abdominal Crunch: 2 sets of 12 reps
Day 2
- 5 minute aerobic warm up
- Plank: 2 sets of 30 seconds
- Russian Twist: 2 sets of 8 reps
- Abdominal Crunch: 2 sets of 12 reps
Day 3
- 5 minute aerobic warm up
- Plank: 2 sets of 35 seconds
- Russian Twist: 2 sets of 10 reps
- Abdominal Crunch: 2 sets of 12 reps
Week 4
Day 1
- 5 minute aerobic warm up
- Plank: 2 sets of 35 seconds
- Russian Twist: 2 sets of 10 reps
- Sit Up Negatives: 1 set of 4 reps
Day 2
- 5 minute aerobic warm up
- Plank: 2 sets of 40 seconds
- Russian Twist: 2 sets of 10 reps
- Sit Up Negatives: 1 set of 6 reps
Day 3
- 5 minute aerobic warm up
- Full Sit Up
For more ab workouts, check out our other article: The 9 Best Ab Exercises For Powerlifters.
Frequently Asked Questions
Is It Normal Not To Be Able To Do A Sit Up?
Yes, it is perfectly normal to not be able to do a sit up. If you are just starting an exercise program, you shouldn't push yourself too hard or strain yourself because your body has probably gotten out of shape. You should start at your own level and work your way up gradually.
Why Can't I Do A Sit-Up Without Someone Holding My Feet?
You can’t do a sit-up without someone holding onto your feet because either your legs are too close to your torso or your torso is heavier than your legs.You are not alone. You can continue to have someone hold onto your feet or move your feet further away to be able to counter balance your torso more.
Why Can't I Do A Sit-Up Even If I Can Hold A Plank For 2-Min?
The reason why you cannot do a sit up even if you can hold a plank for 2 minutes is because either your abdominals or hip flexors are not active enough to lift your torso off the ground.
So How Do People With Weak Abdominals Train Them Without Doing Sit Ups?
The good news is that you can train your core without doing any sit ups. The other thing is that there are different kinds of abdominal or other core exercises that target different areas of the abs which allow for variety instead of doing just one kind all the time or still struggling with sit ups.
How Should A Beginner Sit Up?
The way a beginner should do a sit up with their feet anchored to a weight or immovable object first if they cannot do a full sit up without external influence. Once you can build up to an anchored sit up for a good 15 repetitions, you can then perform sit ups without anything else touching your feet, whilst keeping them on the floor.
Should Seniors Do Sit-Ups?
Seniors should opt for other core exercises other than sit-ups as it can potentially pose a risk of straining the neck or back region. Better core exercises for the abdominals and obliques for seniors are: front planks, side planks, and deadbugs.
Are Planks Better Than Sit-Ups?
Planks are better than sit-ups in two ways: they are better for your posture if you seem to over extend your back, and they do not strain the neck and back area as much as sit-ups. They are performed differently within exercise programs as sit-ups are prescribed in repetitions and planks are prescribed in time under tension.
Check out our other core articles:
Final Thoughts
Not being able to do a sit up is not the end of the world because you can easily work up towards being able to do one.
If you only want to strengthen your core without any specific goals of testing your sit-up capacity, then you can always opt for other potentially better exercises.
Do not treat the full sit-up as the gold standard for core strength or fitness.
About The Author: Norman Cheung ASCC, British Powerlifting Team Coach
Norman Cheung is a powerlifting and accredited strength and conditioning coach under the UKSCA. He has been coaching powerlifting since 2012 and has been an IPF Team GB coach since 2016. He has experience coaching various lifters, from novices to international medallists and international university teams. Alongside coaching, he takes an interest in helping powerlifters take their first step into coaching. He currently runs his coaching services at strongambitionscoaching.com.
