Worst results on 10K and 9K than on half marathon splits (Read 316 times)

I wouldn't be able to tell why, but I suck at short distances:

I have done a 10K in 42:22 and a 9K (cross country) in 41:48... and I was exhausted. I was feeling like dying at the end and wanting to throw out.

My pace in the 10K was 6:50, on the 9K a shameful 7:30... while I my half marathon pace was 6:53... and I could have done 6:50 easily.
I felt worse after yesterday's 9K running a bit over 40 minutes than running at a way faster speed for almost 3 times the distance. Sure, I hadn't trained for two weeks but the 10K was supposed to be in my peak period.

And it's not lactate threshold because the difference is minimal. In the half marathon I hit the 5k at 20:18 and the 10K a bit over 41 minutes and I wasn't tired at all.

And on the other hand I don't seem to improve much in terms of speed at this distance. I feel as if the barrier of 41 minutes was the speed of light, you can approach it but not be faster. And while this happens on this distances I do feel confident to try a 3:15 or 3:10 marathon... not a sub 3:00 yet, but who knows.

It depends on so many factors - Taper, rest, nutrition, if your body is just being difficult on a particular day

1st time I ran a sub 3 marathon 2:56:10 (6:43) , I ran a 10k 3 weeks later in 42 minutes (6:47)

The 10k was a trail race although not a particularly hard one (2 miles of easy road) and I busted everything I had in the 10k.  Stuff happens - I was perfectly tapered for the marathon.  I was not for the 10k - I drank beer the night before the 10k and did not sleep well.