I've blogged about this many times before: the 10K is my weakest distance. I think I finally have a physiological explanation why. It doesn't make sense that I can run a half marathon at about the same pace as a 10K, but maybe it's starting to make sense.
I ran the Veteran's Day 10K today. It was in the low 50's and sunny and the course was flat. These are arguably perfect racing conditions, although I would have preferred more cloud cover. I had run this course twice before-- in Oct. 2008 and Dec. 2007. My PR was set on this course in Dec. 2007 at 49:23. Since then, I had run many 10Ks that were pretty much equivalent to that, despite my fitness getting remarkably better over the past two years.
I decided that no matter what, I needed to get a PR today. I have had six weeks of training since my injury so I had no idea what kind of shape I was in. But even though I am not where I was pre-injury, there is no reason why I shouldn't have been able to break that soft PR. My strategy was to start out at a pace of 7:50 and then gradually speed up if I felt that I could. I was aiming for a PR by about 45 seconds, although I knew I was capable of faster based on some recent training runs.
Mile 1: 7:46
Mile 2: 7:48
These miles felt easy. I could hardly believe I was going at this pace for how easy it felt. I was afraid to run faster, though, and I told myself I would really hammer it home on the second half if I continued to feel this good. During the first mile, my boyfriend ran ahead of me. This surprised me because his goal was to run a 7:45 pace, but he ran ahead at what must have been a 7:30 pace.
Mile 3: 7:52 (includes water station)
Mile 4: 7:48
It started to feel difficult and I kept looking down at my HR monitor wondering why my heart rate kept reading 181. It should have been reading 184-185. I knew I wasn't putting forth a true race effort based on my heart rate, but it felt really difficult and I decided that I would save it for the last mile because I didn't want to push too hard too soon.
Mile 5: 7:55
Mile 6: 7:57
I gave it everything I had during the last mile, but all I could muster was a 7:57. I just didn't have the energy to push any harder. I wanted so badly to get a 10K time that reflected my true abilities, but it just wasn't happening. I looked down at my Garmin as I saw the finish line. I had to make it there under 49:00. I dug as deep as I could and found a 7:22 pace for the last 0.2 and my heart rate finally got up to 184, which is where it should have been for the entire race.
My average heart rate for this race was 180. It should have been about 185. I ran the entire race in my "lactate threshold zone" which is considered your 15K or 10-mile pace. I got a great tempo workout in but I didn't actually "race" this 10K. It wasn't like I didn't try. . . I just didn't have the energy to get up where I needed to be. I keep asking myself if I had run the race based on HR and not on pace if I would have fared much better, but I am just not sure I could have actually maintained a 185. I wouldn't be surprised if I maintained a similar heart rate for my upcoming half marathon.
This is something I am going to ask my coach about: why can't I find the energy to get my heart rate (and speed) up to where it should physiologically be for a 10K? I can get my HR where it needs to be for all other distances-- even the 5K! But for some reason, this 10K just kills me every time.
I am happy that I set a PR, and I feel like I ran it as hard as possible. The evidence being that I faded during the last two miles. Maybe next time I go out at a pace of 7:35 and fade down to a 7:50. Establish that I am going to be at a higher heart rate early on and just stick it out. My boyfriend ran a 46:56, which is a four-minute PR.
Finish time was 48:54, a PR by 29 seconds.
I placed 19 out of 205 in my age group. This is the top 9th percentile, whereas I usually find myself in the top 5th percentile for other distances.
Up next: Turkey Trot 5K. Goal is 23:10.