10k & 21k training

[Vaidas]

Thanks Ed for advice, I will stick to them from now on

So here is what I did during the last few days:

5. Saturday - easy run of 1:43:17.0 (18.45 km). Av.pace: 5:36, av.HR: 156 bpm.
6. Sunday - easy run of 30:03.89 (5.00 km). Av.pace: 6:01, av.HR: 143 bpm.
7. Monday - easy run of 57:45.53 (10.00 km). Av.pace: 5:47, av.HR: 146 bpm.
8. Tuesday - Intervals: 6 x 1k R60:
1 -> 4:10.37, av.HR: 173 bpm;
2 -> 4:16.45, av.HR: 177 bpm;
3 -> 4:13.14, av.HR: 181 bpm;
4 -> 4:11.94, av.HR: 184 bpm;
5 -> 4:09.18, av.HR: 186 bpm;
6 -> 4:07.14, av.HR: 187 bpm;

I increased long run because I intend to run a 21k race after the next cycle. And actually I have a question about it - is it beneficial to run 21k race if I want to see how much I can improve over 10k distance this year? Or is it better to stick to running 10k events? I thought since my issue is not with speed, but more with speed endurance it would be good to have this race. Any thoughts?
Pace for the long run seemed a bit too high, but I felt good after the day off, and HR stayed reasonably low. I also took isotonic drink with me, I think it helped me to cope with the run for the last 8k really well.
I am also happy with my 6 x 1k session. I tried not to go out too fast for the first (I didn't really manage it that well), but I was able to pick the pace for the last two.
And how fast should the 5k paced run be?

Thanks in advance.

Best,
Vaidas