I treadle with my feet together. After picking up the treadle with the "feet" as the treadle pedal, I learned to treadle with feet together. If the treadle treadles smoothly then there is very little work done to tire one out. I would always get a workout on the Singer 328k in treadle since it was poorly designed to be treadled.
After watching this video, I now have a better appreciation of the very old lace work since most were done on treadles.
Phyllis, your towels are very nicely done.