I've just finished W4 R3 and it was a challenge! That last 5 min run was what I class as uphill (though my ex-triathlon partner says it's barely a slope 🙄) and I was actually wondering whether I was going too slow, as my legs felt like they were seizing up continually doing the same movement, so I adjusted my gait and that seemed to help a tad.
Wondering now what week 5 has in store... I will trust the process and hopefully report success in a week's time...