Unofficial Sub 21-Minute 5K

Not having heard from Mike by the time I was ready for my lunchtime run, I decided to do a hard-fast workout. But rather than intervals or repeats, I decided to test myself at 5K distance on the treadmill and see if 21 minutes was within my grasp.

I warmed up with a mile; first with walking, then slow jog, backwards jog and finally some gentle pick ups.  I really wasn't looking forward to extending myself to the limit, so I was just trying to enjoy that opening mile and drag it out.

I approached the start of the timed 3.1 mark by bumping the speed up to 8.0, giving me a running start into the "race" since, unlike regular running, it takes a little longer for the treadmill to wind up to my target pace.  I wanted to start out at 9.0 and see how long I could sustain that.  9 mph is a 6:40/mile pace.

I felt pretty darned good through the first 1/2 mile.  Legs were turning over quickly and hips were pulling the knees through smoothly.  Ankles felt good, though I was slapping them down a little to hard, I think.  My cadence was right around 190 strides per minute and my heart rate in the 150s.

The anxiety peaked a little after that as I finished the second 880, still at 9.0.  But now my breathing was more drawn and heart rate was pitching up into the 160 range, but steady.  Legs and hips felt great.

I hit 1.5 miles at 9:56, which is pretty good for me.  But I needed to throttle back and recover a little.  I wasn't going to be able to sustain that for another 1.6 miles.  I slowed the machine down to 8.5, figuring I'd try that for a quarter mile and then decide if I could accelerate again.

I wimped out and kept it at 8.5 for a second quarter...and then a third.  8.5 is a hair over a 7-minute mile, and I knew I was giving back time.  So with 3 "laps" or another three quarters a mile to go, I started to sneak the speed back up, trying to fool my brain as well as my heart and lungs.  I did the next quarter at 8.6.  Then the next at 8.7.  For the bell lap I was at 8.8 until the final 220 when I jumped it back up to 9.2 for a final sprint to the finish.

Heart rate during that final press was 165 and I'd grade the exertion level as a 10 on a scale of 10.  Maybe I'm just wimping out, because I know I have more HR headroom to play with, but I just find it harder and harder to get my heart rate to those higher levels.  Either that means my HRmax is descending or my heart is stronger and more efficient now, requiring greater exertion to get it up in the last 5% of max range.

Anyway, back to the clock.  I crossed 3.1 in 20:58...just seconds under my 21:00 goal.  Yay!  I think I've only managed to do that one other time.  I'd have to search past posts to see.

I recovered surprisingly quickly, and after 10 minute cool down jog at a leisurely 9-minute mile pace, I stretched and showered, workout done.  I'm quite amped up right now, almost wanting to go out for another run this afternoon just to let off a little adrenalin.  If I can do this on a treadmill, I should be able to get under 21 minutes on a flat course.  I did not set any incline on the treadmill or otherwise handicap myself, so it may still not be truth data.  But with just a month and half to go until I turn 50, I'm running out of time to hit that goal marker, so this was a big confidence boost.