Levent Caglar from the charity BackCare, added: “In general, opening up the angle between the trunk and the thighs in a seated posture is a good idea and it will improve the shape of the spine, making it more like the natural S-shape in a standing posture”.
I disagree with the article, or rather with the conclusion. Sitting straight is good for back. The reason for the researchers to say otherwise is that most of people can’t keep their lower spine in the right position. It’s best to show an example, perhaps with a little exaggeration:
When sitting like this, the spine has its natural, S-like shape. It’s seemingly easy, but in fact it’s not. Most of Europeans can’t do this. And for sure, most of them can’t do that for more than just few minutes.
Most of the people, to set their spine in S-shape, need to lean back. Paraphrasing the article, I would say: Being stiff ‘bad for backs’.