A crunch/sit up has gone through a tough time with it being a scapegoat for a number of lower back problems, mostly disc related. The argument being that the repeated flexion movement of a crunch can lead to increased pressure on the discs in the lower back and increase the prevalence of injury. This coupled with the action of strengthening into a flexed position can further compound poor posture that we have likely developed through sitting in a flexed position all day.
While this thinking isn’t wrong, I myself agree with it, I also however think there are many benefits to a crunch or sit up that need to be weighed up and the most important factor when performing these flexion exercise comes down to timing and exercise selection.
Some of the benefits can be the increased amount of fluid and nutrition to the posterior aspect of the intervertebral discs due to the repeated flexion movement.
Spinal flexion exercises can strengthen the discs increasing their tolerance to flexion movements and reduce the risk of further injuries.
You can increase your spinal range of movement and prevent loss of movement in a forward flexed position. This could help with reducing your risk of injury.
Building a six pack. Yes, there are other exercises which stress the rectus abdominals but ultimately the muscles primary function is forward bending so to optimise the muscle building process then you need to forward bend.
Improved performance. The forward and backward bending is a key movement in many day to day tasks therefore training this movement can help transfer to these activities.
About the author
Michael is an Osteopath, trainee strength and conditioning coach and competitive powerlifter.