If you do them right and with a heavy enough weight, they're a pretty good combination of cardio, explosiveness, and functional strength that hits a lot of the posterior chain muscles. Kinda similar to going heavy on the row machine in that way. Most people shorten the ROM or use too light a weight so don't get the benefits. I did 3x45sec @ 16 kg yesterday and am feeling it in my back. Her form is laughably retarded but at 450 lbs the only exercise she should be doing is many sets of fork putdowns. "People" of that size have so much fucking blubber that they CAN'T do proper form on most exercises cause the fat gets in the way.