Prolonged sitting is bad, the same goes for standing. Okay, how about regularly shifting between the two by some given intervals, is that still bad?
Interestingly, the risks of mortality between the two conditions, sitting and standing, appear to be causally different.
Our understanding of the former is supported by a large body of research demonstrating a general association between sedentary time and mortality. However, occupational sitting is not strongly associated directly with diseases like diabetes and heart disease. Hence, it appears that sitting is not inherently bad for us (at least in terms of mortality) but because we are not moving enough.
By contrast, the latter has most recently been associated directly with heart disease, adding to the body of research linking it to other health conditions “such as lower back and leg pain, cardiovascular problems, fatigue, discomfort, and pregnancy-related health outcomes.” The authors of the first paper, above, suggest that excessive standing may be causally linked to heart disease as a consequence of “blood pooling in the legs, increased pressure in the veins and increased oxidative stress, ... which can contribute to an increased risk.”
It should be noted that this research has been focused on prolonged occupational standing, without the opportunity to sit or move. Indeed, more generally, it is recommended that both prolonged static sitting and standing postures be avoided. So yes, the literature certainly does support the notion of shifting regularly between the two conditions. And of course, we should be as active as we can outside of our sedentary occupations.
I hope that is helpful.