BookFinder 

Riding this afternoon late I got to about the 12 mile point in a well known ride and had to stop and lay out on the pavement. The group leaves from a down town staging point and rides out and back on the same route.

I felt okay while laying down, but every time I stood up I got light headed. One try in particular I "flopped down" instead of easing myself back down to the pavement. The onlookers were sounding like they were talking in a barrel from a distance.

Thankfully I had plenty of company. Opinions varied from "he bonked" to "his blood pressure got too high" to "he is dehydrated."

After around a pint of Gatorade, a pint of water, and an energy gel my equlibrium came back and I rode back towards town for several miles. One of the cyclists who stopped and then rode on came back in his truck and gave me a lift back to my vehicle.

Looking back on it, while I had sipped water all afternoon knowing I was going on the ride, I had not eaten since lunch. Also, just before I stopped and had to lay out I put forth an extra measure of exertion to outrun a dog. Fortunately, I dd not have to stop until he had given up the chase!

So I'm curious about "what are the degrees of bonked?" And, "Is there a classic slate of symptoms?"

I want to plan as to avoid a replay of this afternoon.

Thanks in advance,
Rick

Carbonfiberboy 

How much do you think you drank, total, that day before the ride? At what time did the ride start? How many miles/week have you been averaging for the past 3 weeks? How fast do you usually ride on the flats on this ride? Do you lift weights? Had you eaten or drunk anything with calories near or after the start of the ride? What was the temperature? Were you nauseous? Why did you stop?

Not BP too high. Maybe too low. Maybe low blood sugar. Maybe both. Maybe low sodium. Not a "bonk."

Never drink water all afternoon before a ride. If you want to be sure you are hydrated, drink water with electrolytes the day before.

Keith S

Sounds like your blood sugar was low, which is why after the gatorade and gel you felt better. Always try to have something to eat 1 to 2 hours before your ride.

BookFinder 

Thanks to both of you for the feedback.

I ride this route regularly and rode it on Thursday of last week and never bobbled. The only factors that were different today (now yesterday) was a slightly faster pace (15 mph vs my usual 13 mph fitness and easy conversation pace), and I did the sprint to outrun the dog. The sprint was at least a half-mile and I think that was the "tipping point."

After becoming satisfied the dog was no longer a threat, I felt a need to rest and take a drink of water, and opted to stop and speak to two other cyclists who were stopped at one of the turns. After I stopped and unclipped my head began to spin.

Low blood sugar is a cause that I had not thought of previously through this evening. Before I go out this coming Thursday I'll make sure I prep properly.

Is there a particular "water with electrolytes" that either of you would recommend? (Or, a suggestion for a mix that I can put together on my own?)

Thanks again.

chewybrian 

+1. The symptoms you describe, plus the fact that you say you had not eaten for a while, would lead me to think low sugar. It's no fun, but you handled it right, getting some sugar and taking it easy.

Carbonfiberboy 

I have thrown the knuckle-bones. Your near-fainting spell was the result of post exercise hypotension (google). This was caused or made more severe by low blood sugar and possibly low plasma sodium levels. If you had kept riding, you may have eventually experienced the more normal symptoms of low blood sugar - hunger, weakness, visual hallucinations, but you wouldn't have fainted.

HEED from Hammer Nutrition is good. NUUN is good. Hammer's Endurolytes are good. I use Cytomax 'cause it's cheap, but it's not much for electrolytes. However, hydrating the day before gives your body 24 hours to get its electrolyte profile squared away.

Google as above, and google "hyponatremia".

cyclehen

Don't let anyone diagnose you over the internet. Get checked out by your doctor to rule out any potentially serious problems. My father had a serious heart valve problem discovered after an episode of dizziness that resolved on its own. Being unable to get up after a 12 mile ride doesn't scream bonk to me.

BookFinder 

I made a stop at Academy Sports locally today and saw the HEED on the shelf. Thanks for the recommendations -- I'll look into it.

Re, diagnosis over the internet -- I agree. In fact, I already have a physical on the schedule for September 10. Recalling that I made this exact same ride Thursday last week without a problem, I'm not in a panic. However, I'll make sure to eat and hydrate right, and then take it easy the next time I am out.

FGI, I am not a racer and really don't get into even the good natured competition for the club rides. Rather, my riding purposes are about equally split between modest fitness goals and comradery. After thinking and reading on it I attribute this incident to getting there physically unprepared, but I'll all the same make it a point to raise the issue during the physical.

Machka 

Here ... these are reasonable descriptions of the progression a person goes through as their blood sugar level drops. And bonking is simply that your blood sugar level is dropping.

https://www.hypoglycemia.asn.au/artic...t_is_hypo.html
https://diabetes.niddk.nih.gov/dm/pubs/hypoglycemia/
https://www.emedicinehealth.com/low_b...a/page3_em.htm

Usually the irritability one is the one that lets me and everyone around me know I need to eat something long before any weakness or anything comes along.

BookFinder 

Thanks. I spent more than an hour reading at those links and finally created a folder and saved them.

eshvanu

If you wake up with EMT's giving you oxygen and an IV, that's considered an uber-bonk!


I always eat 1-2 hours before a long ride. For my daily commute (10 miles one-way), I make sure I eat breakfast even if I'm out-the-door only 20-30 minutes after eating.

I find I need to drink more water every day than before I started riding again in mid-May. I do my best to drink at close to 100 oz of water, and usually a couple glasses of fruit juices and a glass of gatorade, every day I ride. I sweat a lot while riding, since I'm a Clyde, and the extra water seems to help keep my hydrated.

Dion Rides

Have you been tested for diabetes?

This was definetely low-blood sugar but I would check it out with the doctor. Next time, eat!

benajah

Bonking is when you muscles run out of glycogen, not blood running out of sugar.
Sounds like there was something else going on cause 12 miles is nowhere near far enough to bonk, takes at least 2 hours. Probably best to go see a doc if it keeps up. Could have been anything.
Were you hung over? That will do it every time. I did the Chicago Accenture triathlon really hung over and it took me a week to recover.
Dehydration could be it, a heart issue, or simply having a bad day. Could be anything.

benajah

Generally, at least for me a bonk begins with it feeling like I am going up a slight grade on what is actually flat ground, then I just cannot seem to generate any real power, then my heart rate drops and breathing slows for a given grade and speed of and finally my legs just give plain out.
The biggest sign that it is a bonk as opposed to something else is that "heavy legs" feeling. Not worn out legs, just heavy. It really sneaks up on you slowly, hard to notice, and that is how it gets you.

prathmann

I agree with Carbonfiberboy that the dizziness and fainting are primarily a result of a sudden drop in bloodpressure rather than a typical bonking episode. I experience this quite predictably if I rest for a short time after exercising and then try to get up at all quickly. The first time it happened I got the classic rapid narrowing of my field of vision just before everything went black and I plopped back down again. Since then I've learned to recognize the symptom and sit back down (or even lie down) immediately and then get up much more slowly.

BookFinder 

Okay, now for an update.

Last Friday morning I went for (fasting) blood work and today they called. They checked for blood sugar, thyroid, B-12 deficiency, cholesterol -- basically everything, and everything is normal. So that is good news. My thought at this point is to write this one off as unprepared in terms of both food and hydration.

However, as the last step in this adventure, next week on Friday I have a complete physical on the slate. I have a feeling he is going to look at me and say, "You are doing fine for a man your age" ... whatever that means.

Thanks again to all for the feedback and insights.

Via edit -- I totally forgot this. A week ago today I went to a cardiology appointment that was already on the schedule. No problems there, either.

But hey! If I end up like a guy I read about one time who got great checkups only to fall over dead the next week, it was nice bantering it back and forth with you all...

LJ325

I read this thread when it was first posted - I'm glad to hear everything came back within normal limits. Your suspicion of food / water deficiency is probably correct. Better luck next time. Stay safe.

Richard Cranium

It's worth noting that the term "bonk" isn't hardy scientific -and is often misused to describe any situation where some one no longer feels like exercising.

The original meaning of the term - at least as I understood it from about 20 years ago -was to mean -
"a substantial and rapid drop in blood glucose levels due to sustained intense exercise." In medical terms this is known as exercise-induced hypoglycemia.

However, the term "bonking" has now come to mean any situation where the activity of a person results in fainting, severe fatigue or other negative symptoms such as cramping or digestive upset.

The only way to really know how serious a "bonk" is would be to know the vital signs of the person experiencing the bonk. The "pure bonk" is only experienced by well-trained, iron-willed athletes while training and racing. And it is always dangerous.

The everyday "bonk syndrome" of recreational cyclists may or may not be serious - that will always depend on a variety of factors combining to compromise the person's health.

C_Heath

go to the doctor.

too many answers above.

hearing people talking in a barrell is not bonking.

BookFinder 

Thanks, but please note I've already been to the doctor. The cardio doctor, the GP doctor for blood work, and I'm going back next week for the physical.

Sea Green Sky

Benajah is correct. And it will take much more than 12 miles for your muscles run out of glycogen.