I just did my first workout B in stage 3 this morning. I was a bit confused by the layout of the last 4 exercises. It says "alternating sets" then "abdominal circuit" then "prone cobra" as separate exercise. Are we alternating the abdominal circuit with the prone cobra, or are we alternating exercises in the circuit followed by 3 prone cobras in a row? The latter is what I did this morning mainly because I didn't realise it could be otherwise until I was halfway through.
Second question. I am working out at home, so don't have access to a back extension machine. The home alternative is to do prone cobras but since there are already 3 x90sec worth of these later in the same workout I would prefer to do something different. I have never seen a back extension machine but I had a go at doing something similar based on the description in the book. I used my step to support my hips and hooked my feet over the bottom part of my cable machine and tried to do the manoeuvre in that position. Does that sound right? (It was definitely hard!) Or if that is ridiculously wrong does anyone have any suggestions of similar exercises to substitute?