In general, poor posture leads to a forward tilt of the pelvis, usually from tight hip flexors. This causes the abdominal wall to lengthen and weaken. As a result of the forward pelvic tilt, there is an excess curvature of the lumbar spine (lordosis) causing the spinal extensors to chronically shorten and weaken. Another detrimental effect of this forward tilt is a weakening of the gluteals. The glutes play a major role in hip extension and stabilization of the pelvis and lumbar spine.
Upper Body Implications
In the upper body poor posture commonly presents with rounded shoulders and a forward head. This chronically shortens the pectorals, neck extensors, upper trapezius, and shoulder internal rotators. This leads to a weakness in the upper back, neck flexors, and shoulder external rotators. This causes a constant strain on the ligaments of the shoulder and neck leading to dysfunction and increased chance of injury.
So your mom was correct: sit up straight, do not slouch. Be aware of how you are sitting, typing, sleeping etc. Small changes in posture will substantially decrease the risk of injury, and you will feel better and move better.
Stay tuned for the next installment of public safety fitness and wellness where we will begin to give you stretches and exercises that can be done in your home or duty station, to work on some of the problems we have talked about and hopefully keep you fit, well, and un-injured.