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Are you making the classic sit up mistake?

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 inn 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 enables 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, exactly 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 as 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 the one responsible for flexion of the spine get very little stimulus.

The same is true with straight leg sit ups which put enormous pressure on the lower spine, requiring a huge effort from your bio mechanically disadvantaged hip flexors. This will cause lower back discomfort and likewise stimulate the abdominals for a very small 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 exercise especially for beginners which are much more effective such as the crunch or abdominal curl exercise.
 

The Crunch or Abdominal Curl Exercise

The crunch is an excellent exercise which keeps the abdominals under tension for much longer, it's performed with feet unrestricted and legs at 90 degrees reducing the involvement the hip flexors can have in the exercise action.

How to perform

To start, lie on your back in the supine position with your legs bent and feet flat on the floor about hip width apart. Place your hands up by the side of your head either so your finger tips are pointing at your head or loosely supporting the back of the head. Contract you abdominal muscles lifting you head shoulders and mid back off the floor, as you contract you will be shortening the distance between your ribcage and your pelvis. Hold the position at the top of the movement for a second or two before slowly lowering back to the floor and the start position.
Remember not to thrust your upper body up off the floor; if you feel discomfort in your neck you can place your tongue on the top of your mouth to reduce this.

NOTE

There are instances when a sit up exercise with restricted feet might be applicable to an individuals training plan and certainly more advanced exercise might require fixation of the feet or a similar exercise pattern with straight leg raise which require a strong base level of core stability. 

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