5BX Core Exercise Addenum

As I said in my last post, I felt a pop in my back which caused some mile sciatica down my right leg.  Since then, the sensation has not gone away.  I am, however, able to mitigate it (or even eliminate it) with good posture.  All the same, this episode reminded me of what my physical therapist said to keep my back strong.  With that, I am thinking about adding a core element to my workout regimen.  Part of me is aghast at the idea of adding more to an already solid number of exercises (five basic exercises), but I've also been doing 5BX for a couple of months and my back popping still happened.  I'm doing this so I CAN do 5BX and stay healthy.  On that note, I've been thinking of a few exercises:

Hula-Hoop

I was thinking of doing a total of six minutes for the hula-hoop, with three minutes in each direction for the sake of consistency.  The 5BX program calls for an eleven minute workout, and this would bring that number there.  I would still go running as I would look at hula-hooping more as a core exercise than cardio (metabolically speaking, hula-hooping is comparable to walking).  It's a fun activity that could serve as a cool-down when the other exercises are finished (except the running portion).  However, this would be the only exercise that requires equipment (one hula-hoop) as opposed to the other exercises.

The Plank

I was thinking of doing a minute plank each day.  Like the other 5BX exercises, this one does not require equipment and can be done practically anywhere.  It's a simple, old-school exercise that does measure core endurance.  However, I don't want to burn out and possibly exacerbate my sciatica.

Any thoughts?  Ideas?