via news.bbc.co.uk
In this study, the patients assumed three different sitting positions: a slouching position, in which the body is hunched forward as if they were leaning over a desk or a video game console, an upright 90-degree sitting position; and a "relaxed" position where they leaned back at 135 degrees while their feet remained on the floor.The researchers then took measurements of spinal angles and spinal disk height and movement across the different positions.
Spinal disk movement occurs when weight-bearing strain is placed on the spine, causing the disk to move out of place.
Disk movement was found to be most pronounced with a 90-degree upright sitting posture.
It was least pronounced with the 135-degree posture, suggesting less strain is placed on the spinal disks and associated muscles and tendons in a more relaxed sitting position.
The "slouch" position revealed a reduction in spinal disk height, signifying a high rate of wear and tear on the lowest two spinal levels.
This is how I've been sitting for years. Laid back.