We were planning on alternating C25K+ Speed with what is now the usual 30mins. Didn't quite go to plan, left it too late last friday to do thirty minutes so we repeated speed (don't let the name fool you, it can still be run pretty damn slow) and did our 30 mins last night.
Wife really felt it - very tired by the end of it - and it gave me a stitch like thing in my neck, but still we managed it.
Wife has a running watch now so like me she can see her pace and things - really interesting and we hope useful, it was very clear initially her cadence was much faster than even the fast bit of the 'speed' run, and then progressively dropped so clearly her impressions of overdoing it initially were born out. A really useful gadget I think to work out where you are doing well and where not so well. We can now target a slower initial rhythm and see how that pans out. Maybe make our own mixes at 157 BPM and see how we get on!
Good news is that we did get a little faster so we are developing!