It's a new catchphrase hitting the interwebs due to a collection of symptoms that are common among those that spend extended hours at a desk or computer that can lead to significant health concerns if not addressed.
The effects of desk syndrome include, but are not limited to:
Sore neck
Eye Strain
Tension Headaches
Neck, Shoulder and/or Back Pain
Altered breathing pattern (up into shoulders instead of down into the diaphragm/abdomen)
Postural changes- Rounded shoulders, Slouching, Swayback, Dowagers Hump
Tight hip, hamstrings, and calves
Cold hands and feet due to decreased circulation
Feel Fatigued without exertion
Decreased tolerance for exercise
This slouched sitting position puts undue pressure on the low back, the forward rounded shoulders pull the muscles of the upper back like tight rubber bands, and head held forward in front of shoulders/chest adds to this effect, and starts to interfere with arm range of position creating a pinch point for the supraspinatus tendon that can lead to rotator cuff injuries.
The Fix
Check Your Egonomics
Monitor at eye level, Chair that is adjustable in height, tilt, and with low back support, are you able to change to avoid getting stuck in one position for too long.
Being stuck too long in any one position/posture is not beneficial
Good Posture is a Myth
Instead think in terms of am I able to perform XYZ task efficiently, without discomfort.
If you can't then it's time to change position to one that is more efficient
Get Your Blood Pumping
Knee highs, Squats, jumping jacks, sun salutations, stairs, stretch, walk, go into the opposite ranges of motion. Sustained inactivity is detrimental to your cardiovascular health. Poor circulation leads to cold hands and feet, varicose veins, leg edema, and lowered tolerance for moderate to intense exercise.
Your heart, arteries, and capillaries are made of various amounts of smooth and cardiac muscle that need to be challenged. Just like any other muscle you either use it or you lose it.