Back in July I ran the 2006 Seafair Marathon in about 4:11. I was hoping to beat 4:00, but I had not really trained enough for that goal (slacker!).
My race plan for this event was to follow a race pace chart I was carrying, created from the Seafair Marathon pace calculator. I was aiming for 3:58 to give myself a bit of margin. Here's an Excel chart of the data as recorded via my Garmin Forerunner 305.
Analyzing the details of this chart is informative:
- I stayed on my planned pace (green line in minutes per mile) fairly well (red line, minutes per mile), and in the first half of the race I was beating it a bit. I recall being about 2 minutes ahead of pace by the 13 mile mark.
- My target heart rate was 150, and I'd allow some drifting up during the race. I was hoping to not exceed 170. Right from the start, it was past 150, and as you can see on the blue line (in beats per minute), it kept going up and up. It bumped near 180 in the middle, but that was a silly fluke- talking on the phone (!!!) made me ignore my pace for a bit and I went too fast. It recovered, but you can see the steady upward march of my heartrate continues. By mile 20, it was past 180.
- I was off pace after mile 19 which was OK for a while because I had that two minute buffer, but by mile 22 that was all gone. So I needed to catch back up.
- But by mile 23, my average heart rate was pushing 190. My Garmin said my peak HR was 191.
- And that was that - it was time to walk. You see the spike on the red line as I my pace slows and on the blue line as my heart rate drops back down.
- After that rest, I felt I could start running again to the finish.
Clearly the problem overall was heart rate. It started too high, stayed too high, and was finally the critical limiting factor. My body was clearly undertrained for the speed I was trying to run. My legs were fine, I could do the pace - but my cardio system couldn't provide that much energy for 4 hours without being overtaxed.
What this translates to is that I need to become more efficient at producing energy below lactate threshold, so my body doesn't have to work so hard (as evidenced by my high heart rate). That's going to be my training focus for the early part of my Ironmn Arizona 2007 training, as I work on building base miles.
BTW, at the time I felt I probably could keep running at mile 24, but decided not to "on my own" since I wasn't going to make my goal. It's obvious that my body would have removed that choice from me in about a mile anyway. There's no way I could have been running the last mile without that break at mile 24.
Tomorrow I'm running the Portland Marathon, and I'm probably about equally trained as I was for the Seafair Marathon. My race plan is essentially to keep my heart rate at 150 to start, adjusting my pace as I go and allowing it to drift upward about 5 beats for every 5 miles. So I should be in the 170s or 180s by the finish line, but not blowing up three miles early. Tune in for race results tomorrow...