Core strength....you're saying it wrong, most of the time

This blog has been writing itself for too long, The number of clients with performance problems that regress or disappear after restoring health to the anterior and lateral abdominal wall has driven this article to be written. Each of them have supposedly strong cores, or so they say. 
Each of them have been told they need to get stronger in their cores. 
Each of them is injured, in their trunk, shoulders and hips..... the middle and corners of their core. 

What's going on? 

Do they need a strong core? How's that been working for them so far?

I know the answer to this....I just wanted to get you to question widely-spread recommendations. I'll reveal my answer to this down the page. 

First, your core needs to be able to stabilise fast. That's priority number 1. 
A slowly responding core causes a leak in the kinetic chain. Altered motor control. Extra movement is wasted movement. Less efficient. Delayed reaction to deliver the strength you own means low reactive strength.

A perturbation to your core's stability requires the quickest possible detection and response....but that's not strength, that's reflexive stability. 

These perturbations occur with every limb movement and head movement. They also occur when any outside force is applied. Think of this... you're an athlete who is hit in the upper chest. The hit forces your chest backwards, relative to your pelvis, causing a stretch to tissues in the front of the trunk. These tissues detect the stretch, signal to the spinal cord neurons. These spinal cord neurons send a signal back to the muscle to reflexively contract - the result is a stabilisation against the perturbation. 

The reason this stabilisation won't work is a) poor detection of the stretch in the tissue, and b) altered neural output. The latter is not very common. The former is very common. Pain or limited mobility in tissue will decrease the reception of information about movement, ie mechanoreception. So, most "stability" deficits are related to altered detection of compression, distraction or shear of tissues. Beyond that, reflexive isometric strength, to resist deformation of tissue is the next biggest deficit. Reflexive isometric strength is actually not that high relative to the forces imposed on it. 

For example, force production and absorption requires 4-5 times as much energy as isometric force. 

So, reflexive isometric stability matters more than strength.

The production of force, through the core, actually comes from the fringes of the core - the four corners in fact, ie the hips and shoulders. The ability for those four corners to apply force, in response to destabilising force, comes from reflexive detection of the force, then isometric stabilisation against it faster than you can plan for it. 

Faster than you can plan for it. 

Planned trunk movements are not developments of core stability. They are developments of trunk flexion, rotation, extension force production, which is not the same as core stability. 

Which leads me to my answer - you need trunk force production - core strength if you will - for flexing, extending and rotating against external loads. This requirement is just one of four types of force use that go through the core. The four of them are: 

Core stability that requires reflexive detection and isometric stabilisation against detected force is a combination of all four. Core exercises that do not involve movement of limbs do not make use of absorption, transmission and reuse. An example is the plank, which is why I questioned it's use. 

High force training makes use of three types of force use - production, absorption and transmission. This automatically involves the core, but much less so in a reflexive way. As such, it is less requiring of true reflexive stability. Primary strength exercises are usually biased towards producing or absorbing force in one direction. A push. A pull. A press. A lift. Fine motor control is not required. Indeed the nervous system does its best to avoid fine motor control. It just needs to exert maximum effort in one direction. Our primary strength exercises are not reflex driven. They’re conscious efforts. Superset movements that are performed on the edge of ability, where the athlete needs to manage their mistakes, are done reflexively and subconsciously. These rich stimuli stimulate the nervous system and set the athlete up for better recovery.

So, when training to express patterns of movement from one position to another, with force, i.e. load training, we can look at training from two perspectives - the High Force Training (designed to stimulate adaptation but not sensitive to, or requiring response to perturbation beyond a single direction of force), and the Functional Training Perspective (designed to improve response, then adaptation). 

The Functional Training Perspective lets you respond first, then adapt. 
The two main ways you can handle force, within the Functional Training Perspective, are Discrete and Continuous. 

The Discrete movements have a start and a finish and are planned movements, "from here to here". An example is a bench press or deadlift. A planned movement has much requirement to respond to force, just to produce or overcome it. They can be slow grinds, or quick lifts. The slower ones still have some reliance on sensory feedback, particularly as the weight is high and causes wobbles. The faster discrete movements, the quick lifts, are also reliant on sensory feedback, but a failure to detect movement can mean responses are not made, meaning faults are magnified by load. A "strong" core in these cases does not assist, but a quick responding core, ie a reflexive core, indeed does. 

The Continuous movements don't have a defined start and finish, they are rhythmical and continuous. Examples are walking, jogging, rowing, swimming, cycling. Again, a strong core that fails to respond reflexively will not serve. 

The exercises that challenge reflexive core stability include those that link discrete movements with continuous movements. There are five main types, and they are all dependent on a rich sensory system that is enhanced by mobility development first, then challenged by these linking movements:

1. When more than one joint is involved in the drill, for example, not an isolated elbow curl, but a curl to press.
2. When both an arm and a leg are involved, for example, a curl to press in narrow split kneeling or split standing.
3. When the arm and leg are on opposite sides of the body, for example, left side curl to press, right side single leg stance.
4. When the moving limb crosses the mid-line of the body, for example, a split kneeling or split standing chop or lift.
5. When both arm and leg are moving around a stable core, for example,  single-leg, single-arm RDL, or even better yet, a full Turkish get up.

Core strength