Week 4 is HARD! I felt ready to move on after the W3R3 so I did. I was fine for the first 3 minute run, but halfway through the 5 minute run I needed to slow down a wee bit from my usual 7.1km/hr to 6.8 km/hr. For the next two runs I went at between 6.5-6.8, but I have to say the last 5 minute run took all my will power. I got a side stitch during my 2.5 minute recovery, and my thighs were burning through all but the first run. It took everything in me to keep going in the last run (and not slow down beyond 6.5 because then I might as well have walked), and when I was done my legs were wobbly and protesting. Laura's really testing me.
The good news is that my recovery is much faster. The recovery times during the run felt ok, and after too I didn't need long before my body temperature went back down and I didn't feel like I was going to collapse.