Toughest Run I had In Eternity

Last night I did a tempo run. (N.B. all information in Imperial measure)

Here's how it looked on the weekly plan.

Thursday

1k intervals

6ish miles

2 mi wu + 6x1K @ 5K pace* w/90 sec recoveries + 1 mi cd

*5K pace = 9:31

I always trust the coach so 6-ish miles is under an hour of running for me ... so I timed my night to eat a light meal with my wife (P.S. Canadian Thanksgiving is in October).  Let the food settle.  Go for my run and be home before everyone got back, shower and read the last couple of chapters of Born To Run.

Here's how it turned out:

http://connect.garmin.com/activity/130756898

Split	Distance	Target	Avg Pace	Avg HR	Max HR
1	2		13:22	118	154
2	0.62	9:31	9:21	142	150
3	0.1		14:23	133	147
4	0.62	9:31	9:26	143	152
5	0.11		13:41	139	151
6	0.62	9:31	9:33	142	149
7	0.1		15:00	135	151
8	0.62	9:31	9:38	143	150
9	0.11		13:28	125	151
10	0.62	9:31	9:37	139	153
11	0.11		14:07	122	153
12	0.62	9:31	9:29	134	147
13	1		15:01	120	143
Summary	7.26		11:40	129	154
Interval	Ave		9:30	141
	Max				153

So how did 6-ish miles turn into 7 1/4 miles?  Why, for example, did I suck so much?  I was marathon-shuffling back on that last split ... I was tired!  Why, on the 8th split did I suddenly want to change hobbies and stop running and take up knitting?

Too many questions.  Here's a simple one:

I'm running the 5k Santa Suit run in Burlington on December the 10th (last year's report), what should my target pace be?