Arch Ups no apparatus

How do I do these or what is a substitute without having the equipment?

Hi Justin,

If you don't have a backstrap for the arch up variations you may use a box, bench, table, couch or counter top (any flat surface will do). You can keep your feet tucked under stahl bars, barbell rack or have a training partner to hold your legs. 

Are there any videos or pics of someone do these variations?

I use a barbell and a box. It works very well. You can see the setup in my thread. 

20 hours ago, Justin Kaplan said:

Are there any videos or pics of someone do these variations?

Take a look at the Foundation One form checks section for visuals. 

What is the name of the straps used for this exercise on the videos?  Could these work on a pull up bar?  

They can be, yes, but you'll need to have something to brace your feet against. I have performed them with a backstrap on a pull-up bar that was near a wall. I essentially pasted my feet on the wall and pushed into it. Here is the link to the gear store where we sell backstraps (within the continental US only): https://www.gymnasticbodies.com/gear/