This week was the week I started doing interval runs. When I was in college, we did interval training. 8x400s or 12x200s. I hated interval training. It was brutal, exhausting, lung-burning. I would be woozy and gasping for breath. At that time I could do 400 meters in around 60 seconds during training and I would be so close to quitting after two-thirds of the way. Luckily our coach would continuously egg us on.
Now my interval training runs aren't that brutal. On Tuesday I did 5 sets of 2-minute runs supposedly 20 seconds faster than my 21km pace. I ended up doing the intervals at a much faster pace – around 90 seconds faster than my 21 km pace! Not a good idea, said my coach. Couldn't help it – it was funny running a fast pace after weeks of boring zone-2 runs.
Today I was scheduled to do longer intervals – 4 sets of 10-munute runs at 20 seconds faster than marathon pace. This time I held back and was quite successful in nailing the pace. It was still faster than the prescribed pace but this time it was around 10 seconds faster. In the end I was breathing heavily but not gasping. I could've gone an extra interval if I wanted. This was even more surprising considering that I only had 4 hours of sleep!
It was interesting that my HR drifted no higher than zone 3, which is between 147 and 165. According to my iSmoothRun logs, my HR was 67% in zone 3 and 28% in zone 2. I was expecting it to reach zone 4, maybe even zone 5. I guess this was because I was holding back from running a faster pace.