How could sitting with bad posture a contributing factor to general health problems?
Digestive system problems
Allowing the chest to drop towards the pelvis puts pressure on the stomach and all the abdominal organs. (Just look at your stomach when you are sitting down; if it bulges more than when you are standing, then you are increasing pressure not only on the stomach but all the other internal organs as well)
Compressing the stomach means there is less space inside it for food and the acid it produces for digestion. This can mean that the food and acid puts pressure on the "inlet valve" at the top of the stomach, which may eventually start to leak. If this happens, you will experience "heartburn" and if it happens frequently this will contribute to "inlet valve" damage and eventually "Hiatus Hernia", a very unpleasant condition where you can no longer lay down after you have eaten as "reflux" then takes place, the food and acid flowing back up into to the oesophagus.
Pressure on the intestines and bowels may prevent them from making their wave-like "peristaltic" movements and be a contributing factor for constipation or irritable bowel syndrome (I.B.S)
Breathing Problems
Allowing the chest to drop towards the pelvis also puts pressure on the diaphragm (the layer of muscle between the chest and the abdomen) Normally, at rest, the diaphragm is used for breathing by moving up and down and pushing/pulling air in and out of the lungs (at the same time this movement "massages" the abdominal organs which acts as a gentle stimulant to the digestive system). When it is compressed, it cannot move as freely so breathing has to take place by raising and lowering the rib cage. This requires much more effort so is less efficient and could lead to sensations of "shortage of breath", even when sitting down!
Circulation Problems
Slouching and putting increased pressure on the internal organs CAN raise your blood pressure (you can test this yourself with an easy to use modern electronic sphygmomanometer - relatively cheap these days - or ask your doctor to compare your blood pressure when you are slouching with when you are sitting with good posture). IF sitting badly DOES raise your general blood pressure, maybe you should also check the increase in blood pressure in your legs (again, if you cannot do this yourself, you could ask your GP to do this!) as if there is a significant increase when slouching, then on a long aeroplane flight, this could increase your risk of DVT (deep vein thrombosis).
