Our bodies have a natural inward curve of the spine in the lumbar (lower back) area called "lordosis". Slouching at your desk while sitting places greater stress on the vertebrae in that area, especially around that L4-L5 region. About 80% of people experience back pain at some point in their lives. Much of this can be avoided by proper posture.
There is also a natural lordosis (inward curvature) in your cervical vertebrae (neck area where it attached to your head) that gets comprimised with poor posture. This can cause your head to assume a more forward position (protracted) and place stress on those vertebrae as well.
Slouching while sitting also affects your respiratory (breathing) actions, compressing the lungs and diaphragm. This will in turn deplete your energy and brain power over time.
Proper sitting position: (possibly aided by a low-back cushion) The lumbar spine (lower back) assumes a more normal lordosis (inward curve), which facilitates a more desireable "chin-in" (retracted) position of the head.
A good way to stay in good sitting posture is set a timer at your desk for every 20 minutes to remind you to re-align. Also, keep in mind that your hip line should be over your knee line while sitting at your desk (in other words, if you draw a line straight out from your hips parrallel to the floor, it should be above where your knees are), and your head should be in a neutral positioin while looking at your computer monitor (not looking up or looking down). Finally, proper height positioning of your keyboard relative to your bent arms is also important. Sit with your arms bent at a 90 degree angle (at your elbow joint), then let your wrist drop down with your fingers hanging. Your fingers should be touching the keyboard. If not, re-position the keyboard either up or down accordingly.
Jack Witt, MS, CPT
Fitness and Health Coach