Low back pain can be very uncomfortable and may affect your performance at work. Sitting upright in your chair without occasionally using the back rest will tire your abdominal muscles. When your abdominal muscles fatigue you begin to have poor posture which can lead to low back pain. The best way to solve this issue is to lean back and let the chair support your body. Sitting for long periods of time can also cause low back pain. Shifting positions while sitting is great, but there is no benefit greater than getting up from your chair every hour.