800 dude wrote:
No good answer here. 10k is long enough that you can enter and exit rough patches. You can be hurting bad at 3 miles, hold the same pace, and suddenly feel better at 4. I think it's because so much of the 10k's pain is about the mismatch between how you feel and how you think you should feel. I always feel pretty darn good at 5 miles because that's when I realize that I'm going to get to kicking range with at least a little something left. At three miles, it's easy to start thinking that there's no way you can go twice as far again at the same pace, and that doubt has the effect of amplifying your pain.
In the 5k, by contrast, I don't think the expectations play as much of a role. The race is characterized by a steady buildup of oxygen debt that gets pretty serious by the end, but in the middle of a 5k, everyone should be feeling pretty darned good.
Exactly. I'm almost always feeling good in the last 400-800m of a 5k because at that point you can maybe start to speed up and get the timing right for your kick. And despite being the most tired in the last lap you can almost always run the last lap as your fastest. So really the pain is just in your head.
But in my best 10k I actually never really felt bad. I went through halfway right on target or maybe 5 seconds too slow, but suddenly I was able to speed up from 5:18-5:20 pace down to 5:10s quite easily and kept speeding up until the end. So of course it hurt the most in mile 5 and 6 but when you know you're running fast or on track to PR, the pain isn't so bad.