Bristol 10K - Post Mortem

Have been performing a post-mortem on my run, comparing to my last effort. A bit of background - I'd been aiming to run 38 minutes, having achieved that in a parctice 3 weeks prior. The practice was at 6am in cool conditions, with little wind.

My conclusion has been one of my body working much harder in the heat, but I still couldn't understand how my heart rate got so high so quickly compared to all previous runs. Stryd is used to measure the average 'power' in watts I put into my run. My April practice run (38 min 10K) stats are shown in screenshot 1.

...whereas my Bristol 10K average watts consumed is much lower, as is my cadence (how many steps I take in a minute), as illustrated in screenshot 2.

Conversely, in my practice run my heart rate (purple) took a good 35 minutes to settle above 180bpm, so my body wasn't too stressed (screenshot 3).

...yet in the Bristol 10K race, my heart rate was consistently 180 and higher after just 10 minutes, in spite of running at the same or marginally slower pace (screenshot 4).

Physically, I felt I was at a similar level of fitness. The two runs were only a few weeks apart, and I’d trained regularly in the interim. I had a cold, but have run with a cold often during the past 6 months and it hasn't effected me THAT much. The only attribute I can find that was dramatically different was running in the sun, in a much higher level of heat.

I always imagined the effects would be dehydration - not an actual dramatic difference in heart rate for the same level of performance. But according to this, heat effects heart rate:

https://www.runnersworld.com/race-training/training-in-the-heat

"Furthermore, both temperature and humidity increase heart rate and amplify these effects. At 60 to 75 degrees, heart rate increases by two to four beats per minute. From 75 to 90 degrees, heart rate increases up to 10 beats per minute, and humidity increases it even more. Perceived effort is accordingly much greater as both the temperature and the humidity rise. "

Guessing then that my body just isn't strong enough to cope with that pace at that temperature and humidity. I had no idea at the time, so ran the target pace until my body completely overloaded, and in doing so made myself pretty sick. I had to walk on two occasions. The first due to nausea. The second shortly before the finish, when my chest tightened up alarmingly (screenshot 5).

Has anyone else experienced such an alarming difference in heart rate when running the sun?
1.jpg 12.3K
2.jpg 12.5K
4.jpg 12.6K
5.jpg 71.6K
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Comments

  • Obviously it's a bit harder in the heat - there's no point practicing at 6am for a race if you're racing much later in the day. Train as close as you can to the racing conditions.  I think this is why London was so brutal this year - nobody had been able to get any runs in in the warm, let alone the heat of that day. 

    Also I think you might have still been tired from the 10k 'practice'.  Save the racing for racing day - by all means do fast stuff - but not for the full duration of the race you're entering. 
  • > @cougie said:
    > Obviously it's a bit harder in the heat - there's no point practicing at 6am for a race if you're racing much later in the day. Train as close as you can to the racing conditions.  I think this is why London was so brutal this year - nobody had been able to get any runs in in the warm, let alone the heat of that day. 
    >
    > Also I think you might have still been tired from the 10k 'practice'.  Save the racing for racing day - by all means do fast stuff - but not for the full duration of the race you're entering. 

    Thanks Cougie.

    Yes, maybe that was the case. To be honest, most of my training consisted the fast stuff, building up my distance to 10K in the process. I could have been tired, but I'd been training similarly for 5 months and my body had been holding together ok. Not the most sophsticated method, but it got me down from a 45min 10K in November.

    Maybe the sun/adrenaline of the occasion/nerves/having a minor virus all played their part. Just kind of annoying that the end result was me delivering a 40 min time when I was gunning for 38. Oh well :(
  • Better luck with it next time - any 10k's planned whilst you still have your fitness ?
  • Thank you :)

    I'll probably do it again next year, but not sure if I'll put in the same level of effort or not.

    For now I'm just going to put some weight back on and have a rest for the next month or so, then probably make a decision. I'm considering just running 5Ks once or twice a week until the end of the year to maintain a basic level of fitness, then see how I feel.

    It's hard work, and having two kids/cycling to and from work... it was all getting a bit much at times.
  • You could look for another 10k in the next few weeks or so. Minimal training needed and it'd be nice to hit your target.  It'll be harder to get back after a lazier winter. 
  • Could do, but... nah, not for now. I've already put back on 1.8kg! Quite enjoying eating and drinking!
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