In the neutral posture the muscles absorb the shock of impact when the foot hits the ground: the forces spiral up the legs, with the muscles dissipating the force before it reaches the hips and lower back.
As in previous blogs, the diagram shows typically tight muscles in red, with lengthened muscles shown in blue.
As with the sway-back posture, flat-back has hips tilted backwards.
The knees are often locked and forward of the mid-line. The hamstrings and adductors are tight (to maintain balance) pulling the hip down at the back. The muscle running diagonally down from the lower lumbar spine through the inside of the hip (called the psoas, or tenderloin) is also tight, again pulling the hip downwards at the back.
The normal curves of the spine are exaggerated in the kyphotic-lordotic posture. The flat-back posture is, in some ways the opposite of the kyphotic-lordotic: with flat-back the natural curves of the spine (shown below) are flattened out.
If you've got the flat-back posture, then the following muscles (shown in red in the flat-back diagram) will be tight:
In blue the diagram show the muscles that are lengthened and possibly weak:
To help sort out your aches and pains, you'll need some deep tissue massage work on the tight muscles and a range of other remedial soft tissue techniques to help sort out the imbalances. A good therapist will also advise you on stretches that you can do yourself, and exercises to strengthen up the weak areas.
As ever, if you think I can help, give me a call.