Yesterday was my first official "speed work" run of 4 miles. What speed work entails is this: you run at your regular pace, then pick it up and run much faster for a short time or distance, then slow down again to your normal pace, then do it again. My goal was to do it twice per mile.
I started out later than usual, so it was warm outside, although the humidity was waaaay better than Saturday. Can I just say that speed work is really hard?! I started out running slowly, then picked up the pace for about 1/10th of a mile, running from one post to the next as fast as I could without hacking up a lung and passing out. I had to stop and walk afterwards, until I could start slowly running again. I had never really tried speed work before in a concentrated effort, and I can say it wiped me out!
Now this morning, I can definitely feel it in my legs. They feel pretty wobbly and slightly sore. Speed work is only supposed to be done once a week, and my training program alternates it with hill work every week. After talking with my fellow co-worker, M, who is also training for the same half marathon (his first!), he explained why you should only do it once a week. It's killer on your legs! Hill work is also speed work in disguise, so that's why it alternates with regular speed work. You run up a hill as fast as you can, then either trot or walk down, then do it again. It makes the "fast twitch" muscles in your legs break down, so when your body rebuilds them, they are stronger. This helps you run longer and faster eventually.
Today is my one day off from my training program. Tomorrow morning, it's an early morning for my 8 mile run. I have to mix up my training each week, since my job is not a regular 9-5 M-F work week. I will not want to run 8 miles after work later this week, so it must be done tomorrow! For now, it's mowing the yard, finishing a book, then going to work this afternoon.