Tension headaches are caused by a buildup of stress and strain in the muscles of the head and neck. This stress can be caused by poor posture, such as leaning forward while working or sitting for long periods with your head down. This can cause tension in the muscles of the neck and head, leading to frequent and severe headaches.Back pain is another common symptom of poor posture and sitting for long periods. When we sit in a bad position, our body develops tension in the muscles of the back, hi