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Author Topic: Is bonk training advisable/beneficial?  (Read 8366 times)

Offline Bill.D.Katt.

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Is bonk training advisable/beneficial?
« on: 21/01/2011 02:57:41 »
Last summer I went on a long bike ride, but carried insufficient food with me. About 10 miles from my destination I bonked. All that I can remember from those 10 miles is fading in and out of coherent thoughts/consciousness while taking back rodes to avoid traffic. Bonking is a condition when your body runs out of glycogen stores. When you bonk, your body starts burning fat, and then muscle. The September 2002 issue Bicycling magazine talked about bonk training, where an individual purposefully bonks for a short period of time in order to loose weight -fast. There is evidence suggesting that this is good for you, and evidence suggesting that this is bad for you. Since glycogen is the major food source for your brain, could this cause minor brain damage? I would like to hear the Naked Science consensus on this, good or bad for us?


 

Offline Don_1

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Is bonk training advisable/beneficial?
« Reply #1 on: 21/01/2011 11:38:13 »
Phew!!!!

You had me worried there.

Bonking has another connotation.

Allow me to explain.

Where shall I begin? Well, you see (ahem) there are 'men' and there are the other ones..... you know, (ahem) (whispers) women.

Now the man puts his w
 

Offline CliffordK

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Is bonk training advisable/beneficial?
« Reply #2 on: 21/01/2011 12:31:19 »
I'm not sure that running, or riding a bicycle in a semi-conscious state is healthy, as there could be lethal road-hazards.  Are you doing this alone?  If something goes horribly wrong, then what?

I'm seeing many notes on exercise induced hypoglycemia, and some on "bonking".
http://en.wikipedia.org/wiki/Hypoglycemia
http://en.wikipedia.org/wiki/Hitting_the_wall

Most seem to discuss how to avoid it, rather than intentionally causing it.

In diabetics, hypoglycemia can cause seizures, coma, and DEATH, although I'm not sure severe consequences occur in the non diabetic population.  One doesn't see Marathon Runners dropping like flies.

I have run 2 marathons.  I wasn't fast, and I struggled near the end.  However, when I crossed the finish line, the space blanket was very helpful as my body was in a state where it couldn't regulate temperature. 

Once a year is ok, but I don't think I'd want to do it on a regular basis.

As you know.
The brain needs sugars (glucose, and various similar sugars).
The brain can not use fat, nor can fat be used to make sugars.
Gluconeogenesis can be used to create glucose from proteins.

So, in theory, your body should be able to recover even without the intake of carbohydrates.

Anyway, if you are hitting a hypoglycemic crisis, I would encourage stopping and resting.  Eating is good, but if you recover without eating, that is ok.  If you recover over time, then you can continue, and you probably won't have altered your overall metabolism significantly, but may prevent yourself from riding head-on into a car.

Of course, make sure you do drink adequate water, and perhaps some electrolytes. 

It might not be a bad idea to also check your core body temperature as you can easily push it to over a hundred in the summer. 

    *
If you suspect a heat-related illness, stop exercising and get out of the heat. Drink water, and wet and fan your skin. If you don't feel better within 60 minutes, contact your doctor. If you develop a fever higher than 102 F (38.9 C) or become faint or confused, seek immediate medical help.
 

Offline imatfaal

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Is bonk training advisable/beneficial?
« Reply #3 on: 21/01/2011 15:48:18 »
per Don's message.  That use of Bonk explains a post a few weeks ago when Bill mentioned Bonk and I must admit my thought was "well that's admirably frank - these colonials don't mince their words!"

On the medical side - I would go along with ClffrdK.  I would get a real opinion from a medic or physiologist who knew my personal characteristics before I practised such an extreme form of exercise.  Much as I respect my fellow NSFers - the opinion you need is that of a doctor who knows your medical history
 

Offline Bill.D.Katt.

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Is bonk training advisable/beneficial?
« Reply #4 on: 21/01/2011 16:17:50 »
Haha, I wasn't even thinking of that when I wrote this post. Where I'm from you almost never hear the word in that context, but maybe it will get this topic more views.
Thanks CliffordK, that clears up quite a few questions I had.
« Last Edit: 21/01/2011 16:20:13 by Bill.D.Katt. »
 

Offline Variola

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Is bonk training advisable/beneficial?
« Reply #5 on: 21/01/2011 21:40:58 »
I am quite disappointed that this wasn't the topic I thought it was....  :)

Your body can run for a long while without fuel input, the brain can switch to using ketone bodies. made from fatty acid breakdown  instead of glucose and will maintain function like that, the rest of your body will use fatty acids for energy.
Your 'bonk' happens when your body runs out of glucose from glycogen ( gluconeogenesis) and it has to switch to using alternative fuels, fatty acids or muscle protein etc. It is fine if that depletion and switch is in sync but if it isn't that is when hitting the wall can last.
As for losing weight, it can be done this way but the risk of hypoglycemia is too great a risk, especially when cycling where you need to be realy aware of what is going on around you.
 

Offline CliffordK

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Is bonk training advisable/beneficial?
« Reply #6 on: 22/01/2011 10:43:24 »
the brain can switch to using ketone bodies. made from fatty acid breakdown  instead of glucose and will maintain function like that, the rest of your body will use fatty acids for energy.

I see the root of the confusion.
http://www.ncbi.nlm.nih.gov/books/NBK28048/

Quote
In brain, glucose utilization is obligatory

The brain normally derives almost all of its energy from the aerobic oxidation of glucose, but this does not distinguish between preferential and obligatory utilization of glucose. Most tissues are largely facultative in their choice of substrates and can use them interchangeably more or less in proportion to their availability. This does not appear to be so in the brain. Except in some unusual and very special circumstances, only the aerobic utilization of glucose is capable of providing the brain with sufficient energy to maintain normal function and structure. The brain appears to have almost no flexibility in its choice of substrates in vivo. This conclusion is derived from the following evidence.

Glucose deprivation is followed rapidly by aberrations of cerebral function. Hypoglycemia, produced by excessive insulin or occurring spontaneously in hepatic insufficiency, is associated with changes in mental state ranging from mild, subjective sensory disturbances to coma, the severity depending on both the degree and the duration of the hypoglycemia.

From the same article:
Quote
The brain utilizes ketones in states of ketosis

In special circumstances, the brain may fulfill its nutritional needs partly, although not completely, with substrates other than glucose. Normally, there are no significant cerebral arteriovenous differences for d-β-hydroxybutyrate and acetoacetate, which are “ketone bodies” formed in the course of the catabolism of fatty acids by liver. Owen and coworkers [26] observed, however, that when human patients were treated for severe obesity by complete fasting for several weeks, there was considerable uptake of both substances by the brain. If one assumed that the substances were oxidized completely, their rates of utilization would have accounted for more than 50% of the total cerebral oxygen consumption, more than that accounted for by the glucose uptake.
[...]
Under normal circumstances, that is, ample glucose and few ketone bodies in the blood, the brain apparently does not oxidize ketones in any significant amounts. In prolonged starvation, the carbohydrate stores of the body are exhausted and the rate of gluconeogenesis is insufficient to provide glucose fast enough to meet the requirements of the brain; blood ketone concentrations rise as a result of the rapid fat catabolism. The brain then apparently turns to the ketone bodies as the source of its energy supply.

Cerebral utilization of ketone bodies appears to follow passively their concentrations in arterial blood [27]. In normal adults, ketone concentrations are very low in blood and cerebral utilization of ketones is negligible. In ketotic states resulting from starvation; fat-feeding or ketogenic diets; diabetes; or any other condition that accelerates the mobilization and catabolism of fat, cerebral utilization of ketones is increased more or less in direct proportion to the degree of ketosis

The question is whether or not you are experiencing ketosis in exercise induced hypoglycemia.

Since you are experiencing changes in consciousness, I would have to conclude that during heavy exercise, the blood concentrations of glucose are dropping without an adequate ketosis response.

I guess one can't believe everything one hears in school   [xx(]
 

Offline Variola

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Is bonk training advisable/beneficial?
« Reply #7 on: 23/01/2011 11:30:40 »
Well ketone response will only really keep the brain alive and functioning so you don't die, it is not the fuel of choice. This os why many people who try Atkins type diets experience mental sluggishness and confusion. But that is an aside from hitting the wall, which is where there is a delay in the body going from gluconeogenesis to lipolysis.

 

Offline Bill.D.Katt.

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Is bonk training advisable/beneficial?
« Reply #8 on: 23/01/2011 16:40:06 »
I have a friend who is diabetic who informed me that ketosis over longer periods of time can be dangerous. I'm not quite sure how different body chemistry between diabetics and non-diabetics is though. Incidentally I just read an article about the ketogenic diet, not advised for anyone because it seems to increase risk of kidney stones, the patient consumes massive fat and almost no sugars.
 

Offline Variola

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Is bonk training advisable/beneficial?
« Reply #9 on: 23/01/2011 21:58:12 »
I have a friend who is diabetic who informed me that ketosis over longer periods of time can be dangerous. I'm not quite sure how different body chemistry between diabetics and non-diabetics is though. Incidentally I just read an article about the ketogenic diet, not advised for anyone because it seems to increase risk of kidney stones, the patient consumes massive fat and almost no sugars.

Sort of! If it is not managed correctly it is damaging, hence one of the common symptoms of diabetics is ketoacidosis, but this is not the same as ketosis. The latter is a normal physiological response to fasting or prolonged exercise, after which you eat again and the balance is returned. In untreated diabetics ketosis is uncontrolled and much higher than normal due to their inability to metabolise glucose. This lowers the blood pH due to the high concentration of keto acids.
 

Offline JP

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Is bonk training advisable/beneficial?
« Reply #10 on: 24/01/2011 08:29:48 »
I've done a bit of distance running, including 4 marathons.  Like CliffordK said, you generally experience this somewhere near the end of a marathon when your body runs out of glycogen stores and switches to fat.  Usually you train and carbo-load to last as long as possible in the race before this happens because a) it slows you down a lot and b) it's an incredibly unpleasant feeling.  I only had 1 marathon of the 4 where I was well-trained and carb-loaded enough that I didn't hit the wall at all.

The September 2002 issue Bicycling magazine talked about bonk training, where an individual purposefully bonks for a short period of time in order to loose weight -fast.

This is interesting.  I've heard about training like this to get you body used to burning fat for long races like the marathon, but not for losing weight fast.  I'm a bit skeptical because, even though you're burning fat directly, I'd always heard that a calorie is a calorie.  The calories you burn before hitting the wall should be equivalent in the long run to those after.
 

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Is bonk training advisable/beneficial?
« Reply #10 on: 24/01/2011 08:29:48 »

 

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