Here’s an interesting one from days-gone-by: The Spalding Special Friction Wrestling Machine, or, in other words, two long handles attached to a friction brake. For combat training purposes one would bend or pull this way and that, with resistance of course, focusing a great deal on the muscles of the waist and trunk (what they evidently call the “core” these days.) This might even fall under the “functional” training designation today. Regardless, I’d say this design has many interesting possibilities. By the way, the $12 price tag would equal over $300 in today’s money when adjusted for inflation.