You can do stretches, strengthening and breathing exercises to improve your posture.
But you also have to become aware of your posture and find a way to interrupt prolonged sitting intervals with brief breaks. A good ergonomic chair is also helpful.
Musculo-Skeletal Effects of Poor Sitting Posture:
Poor sitting posture can create muscle imbalances over time.
- In general, your front stuctures shorten, with muscles like your hip flexors and pectorals tightening up - pulling you into a ball. Your crunched sitting posture caves your lower ribs down towards your abdomen which prevents the diaphragm from expanding freely.
- At the same time the muscles of your back stretch out and weaken, especially in the range where they should be working to maintain your posture.
As this posture persists over time, you joints begin to lose normal range of motion as well making it more difficult to assume a good posture.
Correcting Slumped Sitting Posture:
Tailor an exercise program to stretch tightened muscles and strengthen weakened muscles. Additionally, you need a method to become aware of your posture and correct it while you are sitting. This is difficult because as you say, your attention is on your work. Exercise programs like Yoga, Tai-Chi and Pilates are good because they all address and make you very aware of your posture, joint alignments, flexibility, core control and breathing.
Use Specific Exercises to Correct Muscle Imbalances:
Back, Upper Back and Scapular muscles: Back Extensions strengthen your paraspinals. Use different arm positions (Y, T, W, L) to target your lower traps, mid traps, rhomboids and scapular stabilizors. Learn the feel of retracting your scapulas.
You can do these on the floor next to your desk.
Or if you prefer not to get on the floor, use resistance bands for reverse flys, wide rows, narrow rows and rotations.
Away from work, you can also strengthen these muscles using weights, cables and body weight exercises like inverted rows, cable rows, bent over rows, reverse flys etc. And squats are a good for strengthening multiple muscles important to posture.
Core: Plank, Side Plank, Bird Dog and Bridge will stabilize your trunk and spine.
Stretches: - Hip Flexors, Hamstrings, Abs and Pecs. The wall pec stretch stretches the pecs but also contracts the rhomboid and trapezius scapular muscles to help improve the positioning of the shoulder and shoulder blade and is easy to do at work.
Sitting Posture and Breathing Awareness - This sitting posture exercise helps make you aware of your sitting alignment and expanding your diaphragm. Practice a few diaphramatic breaths throughout the day along with this sitting exercise to elongate your spine.
Create your ideal short exercise routine that you can do during short breaks during the day. An exercise ball next to your desk can help you target these muscles in just a few minutes:
Lie back over the ball and stretch out your front
Lie face down over the ball and do the Y, W, T, L exercises.
And consider using the ball as your desk chair for short periods.
Remembering your Posture throughout the day:
This is the hard part. As your muscle imbalances begin to resolve and your diaphragmatic breathing improves, you’ll find that the slouched posture becomes less comfortable and you will automatically begin to sit better. Until then, use a timed reminder or try tying your posture corrections to tasks that you do at the computer regularly. For example, correct your posture each time you check your email or some other specific link. Turn on your web cam for visual reminders.
Keep at it until you feel the improvement. You'll have less problems going forward if you improve your posture. It either gets better - or it gets worse.