Tempo run on the Provo River Trail. Warmed up. Then ran 2.5 out in 13:46. Did not look at the watch until I was done. I was anticipating 13:55 and thought I had slowed down on the last 0.5. It turned out that quite the opposite happened - my splits by 0.5 were 2:49 - 2:44 - 2:44 - 2:44 - 2:43. The heart rate eventually made its way up to 162. On the way back, which is always slower due being a slight uphill, I had quite the opposite experience. I thought I was running 13:52. It turned out to be 14:04. The splits were 2:52 - 2:50 - 2:46 - 2:50 - 2:46. The heart rate was much higher - it climbed to 165 on the last 0.5 for average, and maxed out at 167. Nevertheless, I did feel strong and in control through the run.
Ran with the kids in the afternoon.
Need to do more of those runs to get used to the pain of running at threshold. I wonder about the whole physiological model of threshold, how accurate it is. There have been some recent studies that showed the concept of threshold is rather artificial. I define it as the pace you can sustain for an hour in a race situation. Physiologically, it is defined as the point where you break down lactic acid at the same rate you are producing it. When I reach the threshold pace, my quads start feeling funny. It feels like I am eating a lemon, but the feeling is coming from the muscles. It is as if I could actually taste the acid that is building up. When I was a teenager, I never felt it in the muscle, my breathing would just become uncomfortable to the point of feeing like I was about to vomit. Now I still breathe pretty hard, but I could breathe harder if my muscles would let me. Although I can hold that effort for an hour in a race, when I am in good shape it becomes very uncomfortable and requires a lot of concentration. When I get out of shape or if I am just having a bad day, I feel like I am not working very hard, but just cannot go any faster.
So I have a strong suspicion that the threshold for me is not so much about the lactate level in the blood or muscle, as it is in the ability of the nervous system to deal with it, and still keep firing at the muscle even if the muscle is fussing and trying to inhibit it. I have had quite a bit of experience where an anaerobic workout once a week in combination with tempo runs would raise my threshold pace past the level that I was reaching with tempo runs alone.