Today I got out on the road for a higher intensity 5K distance run. I opted out on a race early in the morning because I had a little residual soreness in my calves form a trail run on Friday, and instead ran the same distance as a progressive run to get an idea of where my condition is at. Started easy on the first mile (about 7:40), notched up a bit on mile 2 (7:30), and then just progressively increased speed through the rest of the run, covering mile 3 in 6:49, and polishing off the last 0.11 miles at a 6:31 pace. Not too shabby, but not quite where I was before I stopped to deal with my ankle issues.
Before I injured myself, I was doing 5K progressives like this in about 21 minutes, and sometimes finishing off at sub-6 pace. Today, I was slower than that and pretty well spent in the final 0.05 miles. That tells me basically what I expected. That is, that I've lost some lactate Threshold.
I've talked before about why we lose lactate threshold gains quickly when we take time off, but retain aerobic endurance for longer periods. Essentially, it's because lactate threshold is completely a physiological adaptation that occurs at the cellular level in our muscle tissues, whereas aerobic endurance involves more enduring changes in the structure and and vascularization of the muscle tissues. Cellular machinery is easily torn up and recycled for other purposes when it isn't needed, but structural changes at the tissue level take more time to break down. They develop slowly when we train, over long periods, and they are lost the same way.
So, it's hi-ho, hi-ho, and off to work I go again on some higher intensity work, to include both some lactate threshold runs, and some progressively longer runs again, in the hopes that I'll be ready to run at least the half marathon when Colorado Marathon day (May 1) arrives.