They found discomfort "significantly" increased for the lower back and lower limb regions, which correlates with previous research suggesting standing desk is responsible for swelling of the veins, which can endanger the heart.
Mental reactiveness also slowed down after roughly an hour and a quarter, however, "creative" decision making was shown to marginally improve.
Professor Alan Taylor, a physiotherapy expert at Nottingham University, said: "The bottom line is that this expansion has been driven more by commercial reasons than scientific evidence.
"But the evidence is catching up and it's showing there are some drawbacks.
"They are not a panacea for back pain, yet companies are worried that if they provide them they'll be sued."
Last year a report by Edinburgh University revealed some office workers, in particular, middle-aged men, spend more time sitting down than pensioners, with large parts of the population described as "dangerously sedentary".
It builds on research showing that a third of Britons are putting themselves at risk of an early grave because of their lack of exercise.
Professor Taylor said that, while future evidence may emerge suggesting some benefits of standing desks, office workers should not ignore current advice to go for regular walks at work just because they are standing rather than sitting.
"Get up, go and make a cup of tea or coffee - don't just stand there," he said.
Standing desks, or systems to elevate computers, range from around $300 to twice or three times that sum.
Some scientists believe their use can help office workers lose weight, particularly if combined with a treadmill to form a so-called "walking desk".
- The Telegraph