If your spine is not well supported when sitting, you will tend to fall into positions that further stress the discs and stretch your tissues,” Eby explains. “Long-term, these positions can result in muscle imbalances and postural changes, with muscle shortening at the front of the hips, the chest, the pectoral area, and the back of the neck, and weakness [developing] in the gluteals, mid-back, and neck flexor muscles.” In other words, poor posture while sitting doesn’t just hurt your back, it literally changes your body—and not for the better. To combat this, anyone who sits at a desk on a consistent basis should invest in an ergonomic chair, especially if you suffer from back pain.