What is it?
There is a general acceptance and acknowledgement that it is important to have a strong core but I wonder what people think it is.
Clients may tell me that their physio has told them that their ailment or postural issue is due to their lack of core strength. The client is then confused because doing what their fitness professional describes as, core strengthening exercises, isn't helping.
I see people in gyms performing the plank until other gym goers are using them as a storage bench for sweaty hoodies. Some unfortunates perform various kinds of sit up until they become bow shaped often adding yet more structural stress to a body already in postural crisis. They are all missing the point.
The core is stimulated into action when we are infants. When a child is first able to stabilise itself upright in its parents arms and stay upright while that parent empties the car and the washing machine. This is core stabilisation. Once functioning it is the root of all basic movement patterns. Creeping, crawling, jumping, climbing walking and not falling over, squatting to pick things off the floor, reaching for that thing you didn't want them to have. All of that involves core stabilisation.
The core isn't a single muscle. Unlike eg the bicep, which is one single muscle(well sort of- it's double headed and crosses 2 joints but you get the drift) -where all the fibres run in the same direction and initiation clearly and simply flexes the elbow.(yes yes it also impacts on the shoulder joint but we are keeping it simple) This makes it easy to work, simply flex then extend the elbow and you are doing it. The core is way more complex. It is many muscles, fan shaped funnel shaped long and short, multi directional and muti-purpose. It isn't necessarily limited to the tummy area. Some professionals think of it as extending from the toes to the jaw.
We can't understand the core by figuring out what it does. It's more about how it supports our structure while we do other stuff. If you lift something heavy it's the core that ensures that 'something' comes to you rather than you to it. There is no one exercise to fix or initiate the core.
I always have an analogy. In this case it's a tree. As a young tree grows it gets bashed about by the wind. The trunk responds by becoming strong and flexible. As the branches grow the wind exerts great forces through the branches to the trunk, in response trunk becomes stronger while maintaining the flexibility to pull back the branches and stabilise itself regardless of the changing direction and force of the gusts of wind. That trunk is your core. It doesn't have to do anything because its job is to stabilise all other actions.
If the core is weak this analogy also works well.
If a tree grows in a sheltered spot and is never subjected to winds the trunk will be narrow and weak (this is true, ask a tree surgeon!) subjected to a forceful wind it will bend, uproot, disfigure and break. If we strengthen the branches until they are heavy they will pull the tree out of shape or break from it.
To treat such an ailment by repairing the break is naive. You need to strengthen the trunk.
You can do as many planks and sit up variations as you like but you need to go back to your simple balances to find your core. Try sitting in your car without leaning back and hold yourself against the turns and you will soon find out if your core is on. You need to be reaching and changing direction and balancing, catching and throwing to turn on the core. There is no one move it is a complication of many which makes it elusive but kinda cool.