What is a tempo run?

I knew it has to do with speed work, but I really had no idea what a tempo run was. A run at the tempo you want to run your race? That's how I used the term myself when I ran 2.5 miles at 12mph pace today. A tempo run. But was it, really?

I decided to find out.

Running Times has an article defining tempo run as "20 minutes of steady running at threshold pace." This is from Jack Daniels, PhD, who coined the phrase (no, I don't believe it is the same Jack Daniels). With that in mind, I did actually accomplish at least one portion of a tempo run, kind of. I ran 30 minutes at my goal pace.

I do not believe I ran at threshold pace. Or maybe I did. I don't know that what I ran was "comfortably hard." I do know I can't run a 5K any faster. I didn't quite make it to 5k distance today. I also know I can't run that for an hour. I wanted to. That was the original plan. I have to work up to that length of time though, because I'm not yet there.

Using this definition, my last race turned into a tempo run. I bonked around 9 miles and had to push hard to finish the last 4 miles. Those last 4 miles were tempo, because I had exceeded my lactate absorbing threshold. I felt that for a week after. Last week's speed work, which I felt into the weekend, also exceeded that threshold.

2B talks about tempo runs as sustained effort, at or just above anaerobic capacity. That is slightly different than lactate absorbing threshold. Anaerobic capacity is based more on heart rate, which is also something I have trouble measuring. Of course, if I had a garmin I could test the heart rate theory. Maybe someone will buy me one for my birthday (hint hint!)

It seems this, like just about anything else, is going to be a quest to find out what works for me. I think I prefer the path I'm on, which is to work at increasing the distance I can run at my goal pace. Doesn't matter to me if I exceed my lactate absorbing threshold in the process, as long as I don't do it the day before a long run. Doesn't matter to me if I push my heart rate, as I seem to do that just be the act of running. Until I do have something (which I won't trust anyway) to measure and give me numbers on that, I'll just have to wing it. It's what I've been doing all along anyway.