Losing Peak Speed, My 4th J P Morgan Corporate Challenge

My running career started from preparation of J P Morgan 5.6km race in 2010. And I got improvement in PB each year (2011, 2012). This year it came to an end. Though I still ranked 1st in my company with more seasoned runners joined this time, I only clocked 24:40, fell 2 min behind my last year PB (22:59). Ranked 231 in the entire field, compared 97th in last year.

Despite the slightly longer (~100m) in course and hotter weather (30min earlier start than before), The top 1% runners seemed to score equally well as before.
I was managed to start near to the front and started slow (from below chart you might found it the slowest start ever). It did not help. I could not speed up to 4:00 pace after 1km mark as I planned, and I could not even keep 4:10 pace, degraded to 4:30 at last, end up with 2min slower than last year. More shamefully, the heart rate was insanely high and it should not come from a runner claimed training with MAF method. It was out of my max heart rate!

Split      -2011 Pace    -2012 Pace  -2012 HR    -2013 Pace  -2013 HR
1km        4:01                3:57              182bpm       4:37               185bpm
2km        4:03                3:52              190bpm       4:13               189bpm
3km        4:09                4:09              189bpm       4:21               191bpm
4km        4:33                4:23              187bpm       4:20               192bpm
5km        4:42                4:20              186bpm       4:32               193bpm

I could only attribute this to the temperature, the heat of the course that burnt my soles because I ran barefoot. I could not pump up sufficient blood stream to the leg muscles and use most to cool down the body and soles... I knew that was not the only reason. I was losing my peak speed, as a result of aging when I entering my 40s. Last month SAFRA inter-club road relay already shown a sign: I could not clocked sub-4min pace in a 2.4km run. If it was 3 years ago, I could do it in a 7.5km course with only 6 month after starting to run. So it's time for me to turn to longer distance, and ultra-marathon as other mid-aged runners did. Bye-bye speed, I'll get it in longer distance.