That sounds like heat exhaustion, or heatstroke, a sign of which is orthostatic pulse and blood pressure change, which is different than fatigue or when your glycogen stores in your liver and muscles are depleted.

Indeed, and it probably is. I don't know all the details, I just know when I'm done I say I've bonked. "Glycogen Bonk". "Heat Bonk". "Dehydration Bonk". "Unknown Bonk".

Today was likely a heat-bonk. Because I was feeling awesome an hour into the workout, did a great VO2 effort, and baam 20 minutes later I'm laying on a table on the side of the road asleep in the shade with people barbequing all around me, which was kind of awkward. Took 45 minutes to get up the backside of GMR to my car, whereas I generally go up that hill anywhere from 22-28 minutes. This heat sucks. I want fall/winter back.

Be careful out there. Look into glycerol:

http://www.cptips.com/glycerl.htm

I know what you mean, but you are not bonking in the usual sense of the word. When you bonk, you just run out of fuel. It is a supreme effort just to get the pedals to go around, but your body in general ,is ok. What we are expierncing up here right now is a mild to moderate form of heat stroke. I've been keeping my rides and runs down to an hour, and a ridicolusly low HR. Even with that, I feel completely drained of electrolytes, and dehydrated. It's been between a 100 and 104 here for over a week and a half, and no let up in sight. I've been going to the coast for 3 days a week, just to get in some mileage. Never thought I would love the June gloom, and actually travel there to get under it....

Over the years, I have noted that around 20-30 min before I have that extreme blood and liver glycogen depletion, I notice that I get a bit lightheaded (ie lack of blood sugar flow to the brain... I guess). My concentration decreases, and I start making poor decisions. This is a sign that food, coke and gels are needed, or I will be forced to stop within a half hour.

Riding home some years ago I noticed that I couldn't make out road signs or any words at all any more. Then I got sleepy and just laid down on the grass for a while.

That is usually a dead giveaway for me.

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kiwipat

per ardua ad astra

Start making poor decisions ? Is that how you ended up with a Cervelo ? You stumbled into a bike shop looking for food and ended up buying a bike.

Its late. The only reason I popped on by is I thought the Subject was "When do you think BOINKING is imminent". Now that I would have plenty of answers - bonking though, not so much.

Monty, was that you truck and pop up I saw parked at the pool (Carlsbad) a couple of days ago. Can't remember what day it was, maybe Tuesday night?

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Mike Plumb, TriPower MultiSports
Professional Running, Cycling and Multisport Coaching, F.I.S.T. Certified
http://www.tripower.org

you know a bonk is coming when you have brief periods when you're not sure where you are.....even though you're on a route you've ridden countless times. you know you've bonked when you get back to your car and realize you've been sitting there for ten minutes with the keys in your hand not sure what to do. then when your brain comes back around, there's that tired to the bone feeling when all you want to do is just breathe and not much else. just one of these trips to bonkville will make you pay attention to your workout nutrition in the future.

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70.3 is the cousin to OD........ Ironman has no relatives! -Simon Lessing

Invariably, I start thinking about food (like a bagel with peanut butter). I know it is a matter of minutes before I will start slowing down. What you got wasn't a bonk, as others have said.

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"Go yell at an M&M"

Two related questions:

1) Roughly how many calories before (true) bonkage? I have heard a rough figure of~2000 calories for glycogen stores, but have gone ~2800 cals with only ~300 calories of gels/drinks without experiencing anything I would call a real bonk. I'm curious how much more reserves I have beyond that. I'm sure it depends on weight (I'm 200#) and pace. Does anyone have a good estimate for calories of glycogen per lb of body weight or muscle mass?

2) On a hot race day, I staggered around feeling drunk for ~20 minutes after an Olympic race. I couldn't walk a straight line, felt disoriented (not just tired) and almost couldn't stand. This wasn't bonking -- was it heat exhaustion or dehydration or what? Just wondering whether I should focus on drinking more or cooling off more next time.

when i'm out of food and i'm thinking of eating grass on the side of the road!

dan...

I do quite a bit of longer rides (would like to ride RAMM in 5ish years).

Based upon my output, I have a pretty good sense of how long I'll last at a given pace...and then adjust my intake accordingly.

To answer your question, I feel a rather obvious spike in "feeling good" followed by the death drop in output....usually within 10 minutes. The "feelin good" stage is now my trigger to think about my intake and make adjustments.

I find that if I'm going hard, like lots of efforts in the upper tempo, threshold, and VO2 range, I can put out around 2000kj of energy before I bonk if I'm not taking in any calories and I weigh about 70-72kg. This is of course what people are usually referring to when they say "bonk", but again, I just say I've bonked whenever I'm totally spent, for whatever reason it may be and will usually just put an adjective in front of it...dehydration-bonk, glycogen-bonk, heat-bonk, unknown-bonk, etc.

Same thing happened to me today on my 35 mile "lunch ride". I was good for the first 30 minutes, fine for the next 30 minutes and then I went into limp home mode. Damn it is hard to put out any power in 104 degee temps.

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Here's a strange one. When I am getting near the end of my rope, one of my ears "clogs" up almost like there is water in it. It happens everytime near the end of long races IF I haven't paid attention to my calories. It's the perfect warning system but myself and my doctor have no clue as to what is actually going on in my skull.

I have a hard time with easy things:

Remembering when I last ate/drank

Calculating pace in my head

Remembering the last split

Calcuating a finish time

Remembering who I am (well, this last one means I'm already in the bonk zone)