I found
https://en.wikipedia.org/wiki/Treadmill more insightful, as treadmills existed long before its use in the penal system.
Note also that while it says "The first US patent for a treadmill "training machine" (#1,064,968) was issued on June 17, 1913." it also says "The forerunner of the exercise treadmill was designed to diagnose heart and lung diseases, and was invented by Robert Bruce and Wayne Quinton at the University of Washington in 1952."
The essay makes it feel like there was no precursor, and that the modern running treadmill has a more direct connection to the 1913 patent.
I'm definitely not saying the essay is wrong, only that there are more details I would have liked.
