We’ve all done it right, gone to do some sit-ups and put our feet under a bar, bench, radiator or anything to fix our feet in place so we can perform a true ‘sit up’.

Restricting your feet for a sit-up exercise

It’s a common sight in most gym’s, I know I’ve seen it many times, however. If you’re doing sit-ups like this, you’re doing them wrong. Fixing the feet enables you to pull harder with the hip flexor, in turn, this puts increased stress on your lower spine, essentially this allows you to sit up without bending your spine. What happens from this action is that the effort required from the hip flexors is increased while the effort required from the abdominals is decreased, precisely opposite to why most people would perform the sit-up exercise with restricted feet.

Overall the sit-up is one of the least effective abdominal exercises, because,  during the sit-up exercise your abdominal muscles spend very little time under tension, even when performed unrestricted. It’s your hip flexors which start the movement, followed by some abdominal activity before finishing with momentum making the exercise ineffective at stimulating the rectus abdominals, our primary core muscle and the one responsible for flexion of the spine gets minimal stimulus.

The same is accurate with straight leg sit-ups which put enormous pressure on the lower spine, requiring a considerable effort from your biomechanically disadvantaged hip flexors. This will cause lower back discomfort and likewise stimulate the abdominals for a minimal amount of time during the movement.

So, what can you do?

If you’re guilty of the above, your probably wondering what it is you should be doing. To start with as mentioned, sit-ups are an in-effective exercise and there are plenty of other exercises especially for beginners which are much more useful such as the crunch or abdominal curl exercise.