Why does my back hurt when I’m doing sit-ups?

Lower back pain is a common issue while performing sit-ups and if this is something that you experience, this is also something that can be improved. By strengthening your core muscles and by learning how to perform the exercise correctly using the muscles of your core and trunk rather than your lower back. 

There are four sections to your core and the main abdominal muscle groups combine to completely cover the internal organs.
These muscle groups include:

Transversus abdominis – the deepest muscle layer and its main role is to stabilise the trunk and maintain internal abdominal pressure

Rectus abdominis (or the six pack muscles) – slung between the ribs and the pubic bone at the front of the pelvis. When contracting, this muscle has the characteristic bumps or bulges that are commonly called ‘the six pack’. The main function is movement between the ribcage and the pelvis

External oblique muscles – these are on each side of the rectus abdominis. The external oblique muscles allow the trunk to twist, but to the opposite side of whichever external oblique is contracting. For example, the right external oblique contracts to turn the body to the left

Internal oblique muscles – these flank the rectus abdominis and are located just inside the hip bones. They operate in the opposite way to the external oblique muscles. For example, twisting the trunk to the left requires the left side internal oblique and the right side external oblique to contract together.

Traditional sit-ups use more of the hip flexor muscles—which attach between the thigh bones and lower back (lumbar spine)—than the actual rectus abdominis (the “six pack” muscle). Since the hip flexors attach to the front of the lumbar spine, if they become overworked tight they can create an anterior (forward) pull on the lumbar vertebrae, which may be a link to the discomfort. Another reason for low-back soreness might be the fact that doing sit-ups on the hard floor. This pushes the spine into a hard surface, which could cause additional pressure on the posterior portion of the spine. Because sit-ups focus on the movement of spinal flexion and use only a few muscles (the rectus abdominis, the external obliques and hip flexors) in the front region of the mid-section, consider selecting other exercises that use muscles on both the front and back sides of the core. If your back only bothers you when doing sit-ups, skip that exercise and choose others that will strengthen the entire core and support better range of movement and stability. 

Performing exercises that can help strengthen your core without the back strain would be a great place to start. Once you have built a strong foundation and level of stability and strength you can then move on to or try a sit-up again. 

Effective core exercises:

Plank holds – this often perceived as simple exercise is great to help you create a stronger core and increase your truck stability. You can challenge the different sections of your core muscles by altering the type of plank you hold. For example ; holding a side plan can help target your transverse and oblique muscles. 

Bird/dog – performed on hands and knees this exercise allows you to work on your stabilising muscles with the strain on the lower back if performed correctly and can be modified or made more challenging depending on your level of control 

Fit ball knee tucks – this exercise also requires some upper body strength through the arms and shoulders but this more advanced exercise can help create a strong and stable core.

Reverse crunches – allowing your knees to come towards your chest rather than trying to jerk your chest towards your knees can be a great alternative to the conventional sit -up.

Sometimes we can still experience muscles strains which can also be what is causing pain or discomfort. Training through these signs can be of detriment so here are some things to consider: 

overstretching or overuse of the abdominals muscles can lead to straining the muscles
Prevention strategies include regular stretching, warming up prior to exercise and cooling down afterwards.
Try keeping good form while playing sport and lifting heavier objects throughout day to day life.

Where to get help if pain persists 

  • Your doctor
  • Doctor specialising in sports medicine
  • Physiotherapist
  • Exercise physiologist
  • Myotherapy