Total time of 50:12. Total distance over 7 miles, but not sure by how much.
TLDR: 6 x 3 min hard/ 2 min easy, plus 1 min hard at end.
Full Version: I hadn't really planned on running a hard workout today, but I realized this morning that I hadn't run one yet this week so I made up a workout on the fly after I started the run. I woke up earlier than normal (5:30am) because I needed to paint faces for halloween. As a result, the entire run was performed in the dark, and I didn't have a good feel for how fast I was running for most of the run. It was around 30 deg F, so I was bundled up. I'm sure the extra clothing slowed me down a little, but I am not sure how much.
I started the workout at the 10 minute mark of the run, running 3 minutes hard followed by 2 minutes easy. I decided to perform 6 reps, with the possibility of running a seventh if I came back a lot slower following the turn-around since the second half of the run would be mostly uphill. I ran out 25 minutes, turning around right as I started the fourth rep. The first and third reps were almost all downhill, with the first a little more gradual than the third. The second and fifth reps both had a mix of uphill and downhill, while the fourth and sixth were almost all uphill.
I felt like I ran pretty well for the first four reps, as I felt strong and felt like I maintained pace pretty well. I felt like I was starting to struggle just a little on the fifth rep, but felt like I was still able to maintain pace. I am guessing that I was between 10-15 seconds slower from 25-35 minutes than I was from 15-25 minutes due to the net uphill coming back. I was relatively pleased with this as I was expecting a bigger discrepancy. I struggled a lot more on the sixth rep as I began to feel a lot of tightness and some pain in my right arm and shoulder and it was hard to maintain pace as a result (probably due partly to extra stiffness following my recent intercostal muscle strain).
I am guessing that with about 8 minutes left in the run I was somewhere near 30 seconds behind pace to arrive back at the house by 50 minutes. I decided that it wasn't necessary to run a seventh rep as I was close enough to goal pace in the second half, plus I was fatigued enough from the first six reps that I thought a seventh would not offer any benefit. Instead I decided to run 1 minute hard as I got closer to the house in an effort to practice running fast when fatigued. I ran hard from 47:30-48:30, and I had made up any deficit lost earlier in the run and was on pace to arrive at the house right at 50:00 when I slowed down. However, I ended up running up the last hill pretty slowly as a recovery from the hard minute so I still finished just behind pace at 50:12.
Overall it was a good workout and I am happy with how it went. I do feel a lot more fatigued than I was expecting as the volume of hard work wasn't excessive compared to other workouts I have performed recently, but my legs feel more fatigued this afternoon. I may just have to take tomorrow morning's run more slowly.
On the first two days of the week I also ran for 50 minutes, but I kept the pace pretty easy both days as on Tuesday I was only 1:00-1:30 faster than 8:00 pace through 6 miles, and Monday felt similar effort wise.