Comments on Emotions for Engineers: Take Care of The Black Box - Exercise for Health, ...

Hi Crazylady, I'm glad the post helped. There is s...

2008-08-21T18:17:00.000-07:00

Hi Crazylady, I'm glad the post helped. There is so much misinformation out there about exercise and diet. I'm pretty sure that i am not 100% right either, but i do believe it's a good working model, even though I may not have all the science right.

Dave, Thanks for the followup post. In addition to the muscular adaptation there is the neural adaptation that is especially strong when first starting to workout. It can contribute to a 20% to 40% increase in strength without any change in cross-sectional area of the muscle. I haven't gotten far enough to really understand the mitochondrial impacts.

Cheers,
e4e

Here's another question: the purpose of "training"...

2008-08-21T08:45:00.000-07:00

Here's another question: the purpose of "training" is presumably to cause muscle adaptation, e.g. increase the number of mitochondria, thus increasing both peak power output and endurance. But is there any adaptation occurring in the training regime before muscle exhaustion? And if not, then does the amount of stored glycogen matter for training?

This is a different question than athletic performance, e.g. if you want to win the gold medal in power-lifting or swimming, you probably want energy stores to be maximized. Maybe this is the point of the metabolic diet you mentioned (lots of material there - still haven't had a chance to read through the details).

Fascinating post! I find the whole subject area so...

2008-08-21T06:41:00.000-07:00

Fascinating post! I find the whole subject area so confusing but your post has really helped me. I'm lately starting to understand more why I can gain weight when I expect to lose and lose when I'm sure I have gained.
I hope to learn a lot more about this. Surely this kind of information should be taught in schools!

Yeah, I was wondering about that. I still wonder i...

2008-08-18T15:27:00.000-07:00

Yeah, I was wondering about that. I still wonder if they've studied this long enough to know whether there is further adaptation that cranks up gluconeogenesis to fill up glycogen reserves. So I sent Dr. Phinney the question. I'll let you know what I hear.

I eat pretty low-carb, probably average under 20g per day. Maybe the workouts I do (slow burn) don't get me to the bonk, but I've yet to experience it since going low-carb. I'm signing up for judo which looks pretty intense, so it will be a good experiment.

I suspect there is a level of activity that would require you to replenish with dietary carbs just because the rate of gluconeogenesis couldn't possibly keep up. Michael Phelps' Olympic schedule is probably an example of this.

Thanks Dave, That's a great paper. In the conclusi...

2008-08-18T15:03:00.000-07:00

Thanks Dave, That's a great paper. In the conclusion, it talks about keotgenic diets not being appropriate for anaerobic activities such as weight lifting. That is the source of my bench press bonk at the gym the other day.

From the paper.
"Therapeutic use of ketogenic diets should not require constraint of most forms of physical labor or recreational activity, with the one caveat that anaerobic (ie, weight lifting or sprint) performance is limited by the low muscle glycogen levels induced by a ketogenic diet, and this would strongly discourage its use under most conditions of competitive athletics."

Cheers,
e4e

Thanks for the links, I'll check them out. Here's ...

2008-08-18T10:29:00.000-07:00

Thanks for the links, I'll check them out. Here's another related paper that coincidentally was cited on Dr. Eades' blog:

http://www.nutritionandmetabolism.com/content/1/1/2

Thanks for the comment Dave. From my experience, w...

2008-08-16T11:02:00.000-07:00

Thanks for the comment Dave. From my experience, when I lift weights or do high intensity exercise while I'm low carbing, I tend to run out of energy at some point and bonk. I don't know if it's due to low carb or low calories. I sometimes do an energy bar an hour or so before I workout hard. That seems to help, although I don't know if it's a placebo effect or real.

Some folks swear by the anabolic or metabolic diet, which looks like a cyclic ketogenic diet. High calories, low carb during the week, then a carbo load on Saturday and Sunday. Anabolic diet fans claim it's not actually ketogenic.

Here are a few links: http://stronglifts.com/anabolic-diet/ and
http://www.metabolicdiet.com/maurodipasquale.htm" (DiPasquale's website)

Here's a discussion thread that has been going for over three years on t-nation.
http://www.t-nation.com/tmagnum/readTopic.do?id=658379 (T-Nation anabolic diet thread).

I believe the claim is that it stimulates the gluconeogenesis pathway.

It would definitely be bad to bonk with a saber tooth tiger chasing you. On the other hand it would likely be a very short effort and you would succeed or fail quickly. So I wonder how much topping off of glycogen would be evolutionarily advantageous.

Cheers, e4e

Good post, though I wonder about the relationship ...

2008-08-16T09:59:00.000-07:00

Good post, though I wonder about the relationship between dietary carbohydrate and the "bonk" you describe. I've been trying to track down whether or not gluconeogenesis will replenish glycogen stores in the absence of dietary carbs, given enough dietary protein. There's excess capacity, I believe, above the baseline requirements for glucose. The question is just whether the metabolic pathway actually goes there. Since metabolism books seem to always be written in the context of modern carbohydrate-heavy diets, it's been hard to track down.

From an evolutionary standpoint, it would seem advantageous to have this ability. I would guess that making a large animal lunch/avoiding becoming lunch to a large animal would have constituted intense physical activity. If sources of dietary carbohydrate were scarce (perhaps during Ice Ages), having a metabolic process to keep glycogen topped off would have been advantageous. A more modern example would be the Inuit following their traditional hunter-gatherer lifestyle.

I would guess that this mechanism does exist in some mammals, such as large predators. The rate of energy delivery from glucose is higher than that from fat, so for brief high-intensity activity, such as running down and killing prey, a carnivore with the ability to maximize glycogen stores in the absence of a source of dietary carbohydrate would have an advantage.