Came across a couple things related to TRX while looking for a picture of a fence mount. Note that the same exercises can be done with other suspension straps. The TRX business model goes beyond just selling quality hardware, so that's one reason it's all over fitness centers and online fitness websites. Cheaper variations of suspension straps are readily available.
https://www.pastemagazine.com/articles/2017/07/bodies-in-balance-trx.html
by Sara Lindberg, a freelance writer specializing in health, fitness and wellness
"The first time I set foot in a TRX class, I felt confident (and maybe even a bit cocky), about sweating it out for a 45-minute class. After all, I’ve spent decades pumping iron, so how hard could a set of straps hanging from the ceiling really be. Well, about 10 minutes in, my muscles were shaking, my core was on fire, and we were just finishing the warm-up. The instructor, who I desperately wished would have a bathroom emergency, reminded the class that a “full-body workout using a suspension trainer is a lot harder than it looks,” and I swear she was staring right at me.
. . .
Even though my first TRX class challenged every part of my body in ways I didn’t know were possible, I stuck with it, and returned the next week for another workout. And the next week and the next, until I finally ended up buying a TRX system for my house. I’ve been incorporating this style of functional training into my overall fitness program for the past two years and have discovered how easy (and beneficial) it is to mix things up with the TRX Suspension Trainer.
In fact, whether you’re a dedicated gym rat, like myself, and use it to complement your strength training workouts or a distance runner who makes it the main form of resistance training for your overall fitness, the countless exercises available, will help you attack your core, increase mobility and flexibility, and build strength. Frankel [former Navy Seal inventor] says that “using your TRX work as accessory exercises or as a stand-alone strength training modality will increase your results by addressing stabilizer and synergistic muscles.”
If you’re looking for a way to get a killer total body workout in without jumping back and forth between weight equipment and dumbbells, then you might want to give Suspension Training a try. Made for indoor and outdoor use, the portability of this workout system allows users to secure the straps to a sturdy structure in their house, or take their training outside and throw it over a tree branch, chain link fence, or even the monkey bars at your kids favorite playground. And the best part: Frankel says the TRX system weighs less than two pounds, fits into any travel bag and takes less than 30 seconds to set up. Quick and easy is always a bonus when it comes to committing to an exercise program.
. . ."
Introduction in the snow by a fencer, in Europe somewhere, 2 min