Thanks for the correction, Chad.
A way I've found is to sit on a seated cable row station, attach a short "t" bar (straight) to the cable, then put the bar around the upper half of your feet or toes. Then, you can contract.
The bar at my gym rotates along its axis, so I have to be careful not to let it roll off my foot.
But, these work.
Also, an afterthought - what if you just stood up, placed the end of a BB or EZ curl bar (weighted if you are the man) on your foot. Then, raise it off the ground by raising the front of your foot.
Hmmm... may try this. Hopefully it won't hurt my feet.