I didn't feel very taxed, but it was clearly exercise. By the end of my last interval, my right foot was significantly tingling, and it was almost numb by the time I walked through the door at about 28:30. The sorest part of my body was right above my ankles, but they didn't hurt. I'm planning on completing the rest of Week 1 on Friday and Sunday. I'm on track to be doing Week 6 during ConTex, who's with me?