Last 100 of an 800

That mmmany races in effect causes exercise-induced hyperventilation. In short, your brain got too much oxygen in a relatively short period of time.

3200 runner wrote:

I am normally a 3200 runner and have never ventured into the 800 territory until yesterday. I went out in a 27 200 and a 55 400 and ended in a 1:55.6. I have never felt so hopelessly dead in the last 100 and had absolutely no kick and as soon as I finished I had a massive headache. I'm sure I could even up the splits but my main question is why did I have such a terrible headache when I finished the race. The race was in the morning and around 70 degrees and I also run a 9:25/4:17 if that helps.

You raced 800m the hard way, hence the massive headache. Good job.

Overbreathing. Not unusual at the end of a race.