Sitting is the new smoking.
Sitting all day in front of a computer can negatively effect your health. We sit much more than we have ever done. Sitting can effect your spine by placing pressure on the muscle, tendons, and disc. I see many patients who have pain from sitting in a bad position ( poor posture) all day.
Another way sitting effects our health is through muscle activity. When we sit our muscles turn off because the body is at rest. This leads to reduced muscle metabolism. This effects lipid (fats) and glucose metabolism and blood flow. Muscle required glucose and lipids to work.
Human physiology is not well adapted to prolonged periods of inactivity, with time spent sitting increasing cardiovascular disease and mortality risk. Health risks from sitting are generally linked with reduced levels of muscle contractions.
Standing some part of the day will help improve our health. When you stand it requires some muscle activation(contraction). Higher levels of muscle activation can improve your health.
In short, sitting all day can cause you to have poor posture and increase your risk of diabetes and heart disease.
https://pubmed.ncbi.nlm.nih.gov/28378964/ https://static1.squarespace.com/static/55b7ffebe4b0568a75e3316b/t/5f29af75c1a0cc18764d8c83/1596567416162/Sitting%2C+Squatting%2C+and+the+Evolutionary+Biology+of+Human+Inactivity.pdf https://pubmed.ncbi.nlm.nih.gov/30409414/ https://pubmed.ncbi.nlm.nih.gov/30929574/