Yasso 800s were discovered by a guy named (what else?) Bart Yasso.
I guess in the running community he's some kind of BFD, but what do I know? I've only been part of the community for a short time, so his name doesn't have the power over me. Yet.
The exercise involves running a series of 10 800s (800 meters, that is). In between each 800, you jog for the same amount of time it took you to run the 800 (for example, if it takes you 5 minutes to run the 800, you would jog for 5 minutes before the next one). It's both a marathon speedwork exercise and a marathon time prediction tool. According to Yasso, the time for your 800s will predict your marathon finishing time. If it takes you 5:00 to run each 800, then your marathon time will be 5 hours. If it takes you 2:50 to run each 800, then your marathon time will be 2 hours, 50 minutes. Get it? You're supposed to start these workouts a few months before your marathon, beginning with 4 800s and adding another one every week until you're up to 10. The final week is supposed to be 2 weeks before the marathon, though the Runner's World article says 14-17 days is ideal, which I find weirdly specific.
Now, I can't say that I was a disciplined Yasso follower. I followed the Run Less, Run Faster plan, which did incorporate a lot of 800s, but also included speedy 400s, 1200s, and 1600s. Wednesday was 17 days before the marathon, and I had 8 800s on my RLRF schedule, so I decided to just go ahead and add two more and see how the complete session of Yasso 800s went. I think they went pretty well. My times for the 10 speed intervals were: 3:45/3:45/3:45/4:00/3:55/3:53/3:50/3:50/3:48/3:00 (though I really pushed it on the last interval and kind of felt like I was going to die). I also didn't rest as long in between because it was 8:30 by the time I started and I was tired. According to the method, I should be able to hit my 4-hour goal.
Whether you buy the science behind Yasso 800s or not, it's still speedwork. Still not totally confident that I can hit the 4:00 mark, but I'm sure going to give it all I've got! 17 days to go!