Researchers have discovered that the beetles can carry loads up to one hundred times their own weight.
Yet they only use a fifth of the energy that, according to the scientists' calculations, ought to be needed.
How they do this remains a mystery.
Rhinoceros beetles are built like miniature tanks and gram for gram are thought to be the world's strongest animals.
The scientists, led by Rodger Kram, of the University of California, Berkeley, put the beetles' strength to the test by loading lumps of lead on to their backs. Dr Kram found the beetles could still move when carrying around 100 times their own weight. When laden with a modest 30 times their own weight, they could maintain their usual walking speed of one centimetre per second for more than half an hour.
But the real surprise came when the beetles' oxygen uptake was measured as they plodded on a treadmill.
The lead-laden insects were found to consume inexplicably small amounts of oxygen.
Calculations showed that the beetles must be using five times less energy than they should.
A report on the findings in the latest issue of New Scientist magazine said: "Kram is at a loss to explain these results. The beetles do not change their gait when carrying a load, and Kram has found no obvious anatomical quirk that could account for their unnatural weight-lifting ability."Reuse content