When I train clients or teach classes, people often question why I don’t employ the use of any traditional “ab” exercises - in other words, sit-ups, crunches, etc. Upon being asked why, my answer is blunt: Sit-ups are useless, if not harmful.
As a quick anatomy review, our core is a system of muscles that work together for the purpose of “anti-movement” in order to stabilize and protect the spine from damaging forces. If you don’t know, your spine is made up of numerous bony bits surrounding an extremely sensitive softer bit that acts as the closest thing you can identify as the root of all pain.
Demons and Pagan demi-gods notwithstanding.
That being considered, it's in our best interest to condition our core in the most optimal way to do the job of protecting the spine. And the best way to do that is to train using this "anti-movement" that I mentioned. What is anti-movement? It's exactly what it sounds like. It's the contraction of the muscles of your core in order to resist movements and stimuli that could result in injury. For instance:
- Activation of the muscles in order to support the spine while in an upright position to decrease the amount of prolonged (and stressful) load going through the joints
- Resistance against trauma that may cause the spine to move through a damaging range of motion (such as a football linebacker tackling you and risking hyperextension of your spine)
Which brings us back to the exercise. Why are we doing sit-ups to train our abs? Sure, some may argue that it's the concentric/eccentric contraction that promotes the most muscle growth to define the abdominals for aesthetic reasons, but at the same time, we're forcing our spine through loaded flexion which is the biggest predisposer to disc herniations. By way of this type of training, we end up not conditioning our core muscles at all to be able to support the spinal column, resulting in numerous back injuries.
Taking a step back to what I said above, true, sit-ups may be the better exercise for the heavily-defined 6-pack that you want for summer. However, it's important to weigh the benefits of function and aesthetics. As an example, if you look at your typical MMA fighter, a type of athlete who needs to be in the peak physical condition to out-perform the opposition, the abdominal area has a completely different appearance than, for instance, a body builder, who has the look we come to expect from television and magazines.
As awesome as Arnold is, which of these two individuals do you think would win in a fight?
And that's how we arrive at exercises such as the plank, side-plank, and deadbug instead. By squeezing the core to resist movement rather than to initiate it, we train the core muscles for their proper, evolutionary purpose.
Yes, I know that this philosophy would clash with that of many others, but if you're a physique athlete, then by all means, do what you need to do to get those chiselled abs. From a health, or even medical standpoint, however, sit-ups have no functional purpose and are more debilitating than beneficial - especially with the amount of time we spend in flexed, sitting positions in modern life.
So, for the sake of your back health, plank away.