Just wanted to post an interesting experience that led me to a new appreciation of "core strength" and what it means.

Due to a history of back problems which i thought were related to being tall and having a desk job, I have always been aware of keep strong ab and back muscles, which was my primary reason for working out in the beginning.

But a few months ago, I went to a new physiotherapist who is a *genius* and diagnosed something none of the others had: my right leg is slightly shorter than my left (about 7mm)!

This was like an epiphany, because it explained everything! You see, despite my working on abs and back strength and stretching, I'd still periodically get back muscle twinges and knots. More exercise was not helping.

On top of that I'd begun to notice pain in my right hip socket when doing long repeated motions like long walks or hiking, which was getting worse and more frequent. I would also get a stiff neck once in awhile.

Apparently, walking on a short right leg all these years has caused my pelvis to tilt. All these years of accumulated pressure in the wrong places has finally added up to too much and resulted in pain and angry body parts.

So with a tilted pelvis, my hip socket was out of kilter and rubbing the wrong way. It also triggered lower back muscles to work asymmetrically to compensate, tightening up more on one side and pulling my spine into a sideways curve.

Because of this inherent imbalance in the lower back and pelvis, by upper back and shoulders on the right tightened up, giving me pain and decreased movement. Sometimes even my neck muscles would seize up.

...all this because one foot doesn't reach the ground as far!

So my physio gave me a shoe insert to raise my right side a few millimeters, and I had several sessions to stretch and pull and massage my pelvis back into a more symmetrical position.

But the real work is up to me -- I have to increase my "core strength" to ensure that I remain balanced. Aside from abs and lower back, I have to work on my glutes and all the specific muscle that supports the pelvis and hip.
I have some specific exercises I have to do to isolate these areas, rather than just (or in addition to) general all-over core training. He also recommended pilates.

The reason I mention all this is because as a result of this experience, I've come to believe that "core strength" includes everything that is not limb-specific, and it's so important that it is strong, balanced and working properly.

I also think it's worthwhile for anyone with persistent muscle problems to go to a *good* physio and work with them to find out the root of the problem. Sometimes it's extremely complicated, so a simple massage won't fix it. A holistic approach is very important.