Diagnose my disaster

Quick bio. Been back riding a year. 48M - two trips through the trainer road already and timed my training for my A race. Actually my only race of the year.

Got to the start line and felt great. Not nervous - wasn’t planning on winning but planned on enjoying.

Disaster strikes
Took off and immediately HR was 170. Assumed it was an error and turned on Apple Watch…yep 170. Took 10 miles of easy riding to get to 150’s where I can ride a lot and this was a 61 miler. The route was quite flat and even downhill at the start.

At 10 miles I felt like I was done and actually summed my vehicle at mile 15.

This was the second worst bonk of my life.
For the record I fought back and finished a very slow 41 mile route.


The collective will need a lot more information than this to even hazard a guess at what might have happened…


FTP 200
Preface day - very high carb load of about 650g
Preface meal - fruit bread with honey 2 hours ahead.

I do not have power data.
Here is the route link Quite and embarrassing bonk - A bike ride in Martin, Allegan County

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Whatever happened it wasn’t a bonk.


What kind of power were you putting out when the race started? An HR spike like that sounds more like an anxiety issue - but you said you were not nervous. What is a fast start event and were you breathing really hard at the start, or did you happen to look at your HR and noticed it was already in the red?


Going to be hard to diagnose based on the information.

The things that would cause me to have a higher heart rate than expected would be:

  • Heat (especially when not acclimatized)
  • Hard start without warm-up
  • Eating too close to riding
  • Illness
  • Nervousness
  • Too aggressive tapering (I need to have a semi-hard short effort in the legs)

True. A bonk is when glycogen stores get depleted. Obviously not the issue here.

You’ve been cycling one year, and this was your only race of the year? How many races did you do last year? What is your race experience, did you race in other sports?

Frankly I’d say it was just nerves. It made your HR spike, which freaked you out more.

Also, why did you look at, and limit, your HR in a race!?


Without knowing you I do not see anything weird in the first few miles of the race. I can see HR is relative high on start. I think quite usual in mass start events. HR starts to increase as expected. I can see the speed raising 20+ mph. The effort of going 20+ mph gravel bike with 200ftp can be in Vo2Max range. Most likely early on race efforts are anaerobic nature and not steady pace Vo2. I see few curves on start so most likely those will cause surges. Possible there were few near misses with other athlates. Some heavy braking and possible contacts? The physical effort + mass start nervousness for sure will elevate HR, After 1.2 mile mark there is downhill where the HR drops nicely.

Ofcourse this is quess work at best :slight_smile:


edit-answered in OP…should have gone back and read the beginning again.

The one I am thinking the most about here is the illness (but I still feel great today with no symptoms).

I might have tapered a bit harder than I wanted due to schedule but I still had three rides that week.

Correct. Not technically a bonk but it felt the same.

Seems like hardly anything for a 60 mile race.

Is this road or gravel? What category?

It sounds like you went well above your FTP at the beginning trying to hang with the group and basically blew up physically and probably mentally. You probably could have recovered in 20 minutes or so.

This almost happened to me the time I did the Tour of the Gila fondo. I’m 56 and starting with a bunch of 20-30 year old cat 1s, 2s, 3s. Within 10 minutes my HR was at the higher end of my threshold heart rate which is not something I can sustain for 5 hours. I pulled the plug and tried to ride the rest at zone 2/tempo going up to sweet spot and threshold on the steeper climbs. In the end I finished top 10 in my age group due to the correct pacing.

Also, it really helps to race more than once per year.

I’d say nerves. Excitement can be almost as bad as fear/dread when it comes to stress (stress is stress and it does not always come from a dark place). Add in what I’m going to guess is not much in the way of recent regular pack riding adding to stress and that’s why your HR spiked.

It also does not take as much as you might think to go “over the line.” 10 watts more than you planned to average at the start plus a repeatedly surging//slowing pack spiking the Nominal Power can often wreak havoc with the best laid race plans in a very short period of time.

I’m not a doctor. However, this does sound a bit like the occasional story I hear about cyclists going into atrial fibrillation. That’s a heart rhythm disorder. It can be treated. If anyone here is actually an MD or even an NP or PA, does this sound plausible?

If true, you could consider going to a doctor, perhaps a cardiologist, especially if it happens again. Here is one story:

Here’s another one:


Absolutely a concern.

I do have an apple watch and can read EKG’s (from my days working in the ER.). AFib is not to be messed with but thankfully I don’t have that.


Occam’s Razor, IMO.

Without power data there’s probably no way to confirm this, but you just went out too hard. Easy to do when you’re tapered and excited for a race. Your legs feel really good - better than they have in a long time - and so your normal power might feel very easy because you’re not carrying long term fatigue, but HR tells you that your workload was very high - probably above your threshold.

This is classic overpacing, IMO, and you are but one of countless people who experience this same thing. This happens A TON in ultra distance racing (marathons, IM, 100K + marathon MTB, etc.). People overestimate what they can hold because they feel great, and these are the people who are getting passed for the last 6 miles of a marathon or hike-a-biking 6 hours into an MTB race.


So true - One of my more painful athletic experiences occurred my sophomore year in college at our conference swimming championships. I was fully tapered and swimming the 1650 yd freestyle. I felt great. Coming out of the 200 yd turn I caught a glimpse of the clock and to my surprise I’d just set a new PR for the 200 free. I still felt great but I knew that was going to come back and bite me. And it eventually did … And the worst part was at that point I was very highly experienced with tapering and pacing and knew better. Just goes to show you no matter how experienced you are, you still need to keep an eye on yourself.

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You read the OP and your first thought is Atrial Fibrilation?!


If this happened to me I would assume it was a blood sugar issue - hypoglycemia

The elevated heart rate and increased RPE sound like that to me. I also get flop sweat, flushed, dizzy, shakey and all of that. All that it takes for me to get low blood sugar is to eat a sweet breakfast and then do nothing. I’ve had issues where I’ve had a pre-ride snack and then get delayed by work (a perpetual problem) and have had more mild blood sugar crashes from that.

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