Abnormal posture is best described as... any body alignment or position that deviates from what is normal.
This can occur in any of the three main postures such as standing, sitting and lying.
The danger from poor posture is usually not from assuming or possessing a particular abnormal body position for a brief moment of time. But the danger lies more from the cumulative affects that occur over a longer time frame of what is of a habitual nature or action.
Generally speaking, your posture develops over time due to habits and lifestyle practices. This can be from your occupation, leisure, sports, school, hobbies, etc.
It is the day-to-day, week-to-week, month-to-month and year-to-year activities that will predispose you to a posture that is not normal.
The years of sitting at school and on the job at your desk. The years on an assembly line bent over for six or more hours out of the day. The years of a sedentary life watching too much TV while sitting in that comfortable recliner or lounging on the couch.
The daily bad posture you assume due to your habits and lifestyle can and should be countered by a physical fitness program that addresses this problem and helps to restore, maintain or promote a healthy normal posture.
What starts out as a forward head position or a flat back will become a global postural problem effecting your entire body.
The lyrics from an old song reminds us that all body parts are in some way connected and effect all other body parts...
"...the leg bone is connected to the thigh bone, the thigh bone is connected to the hip bone, the hip bone is connected to the pelvic bone, the pelvic bone is connected to the backbone,..."
So your posture, good or bad, in any area of the spine will create good and bad reactions throughout your body.
What begins as a lower back pain due to hyperlordosis or pelvic tilt will eventually cause shoulder and neck problems. So that headache you get may be connected to that which is causing your lower back pain.
Posture can also have a genetic origin. It is common to see parents and children exhibiting the same hyperlordosis or more obviously a scoliosis that is structural (genetic). These inherited postures are not, for the most part, readily correctable.
Attempts to fix an inherited hyperlordosis most likely will be met with failure and frustration.
However, there are some who claim to achieve great success in treating scoliosis and you should not rule-out the possibility.
This website addresses posture that is more functional (versus structural) in its nature and can be influenced by exercise, changes in habits and even footwear.
However, genetic abnormal postures can and should be addressed so that they don't become worsened by occupations, habits and lifestyles that can exacerbate an already abnormal posture in a way that it will create more stress.
So, with a proper posture analysis you can recognize both structural (genetic) and functional abnormal postures and develop a fitness program around your inherited posture and personal lifestyle.
If your poor posture is allowed to exist, over time the muscles, joints, ligaments and the stresses that posture exerts will lead to joint and disc degeneration. The result will be... disc disease with herniation, osteoarthritis and of course pain and suffering.
Your posture needs to be evaluated from both a front or back view as well as a side view. This can help to identify abnormal rotation of the body or its segments and abnormal pelvic tilting and spinal curves. For example, is one shoulder more posterior than the opposite one? Is the head rotated or turned relative to the mid-line? Or is your head centered but the entire body has a twist or turn to it?
The longer a bad posture exists, and the older the individual is, the longer it can take to correct it.