Having decided to work on running faster for shorter distances this spring and summer, I assumed the best course to develop speed would be to run 400 meter repeats at a pace faster than I was accustomed to- eventually I would adapt and race faster.
After a couple of workouts I had a hunch this approach wasn't optimal, which was confirmed by an article I found by Pete Pfitzinger in Running Times called Lab Report: Essential Ingredients VII. The article states "well-trained distance runners should progressively increase training intensity to . . . VO2 max," and elite distance runners should include "progressive increases in the volume of training at or near VO2 max." What this means is that the fitter you already are, the closer to your current VO2 max you need to train to further improve your VO2 max."
So what are the best workouts to spike your VO2 max? According to Pfitzinger, "Intervals of two to six minutes typically allow runners to accumulate the most time at 95 to 100 percent of VO2 max" (think 800- 1600 meters). What about those fast 400s I was trying to boost speed with? "Training faster than your VO2 max pace does not provide as great a stimulus to increase your VO2 max because lactate builds up rapidly in your muscles and you cannot sustain that intensity for nearly as long." In other words, they leave you feeling pretty flat.
I believe high intensity workouts need to simulate 5K racing- the closer you get to that level of intensity the better, and I'm not sure that running intervals considerably faster than that works as well as running them right on the pace you are capable of.
The last 2 weekends I've done 2-mile time trials in 11:46-47, a pace just slightly beyond my reach for maintaining in a 5K. Today I ran 3 miles in 18:01 and I felt a dramatic difference. By running slightly slower the first mile (6:01 instead of 5:53), I still felt strong and was able to maintain for 2 more miles. Keep this up, and I believe that 6 min pace will soon feel easier to maintain and times will eventually drop.
I am planning a 5K in 4 weeks, my first one is probably a year, so these time trials are helping get back into the racing groove. Stay tuned.
For dinner.... sushi 50% off at the Commissary!