More refined sugar consumption = more lactic (lactate) acid production??

Short answer is that high refined sugar consumption can impede your liver's ability to deal with blood lactate, but you are unlikely to experience this if you are very active.

When you are talking about refined sugar you are referring to sucrose (or possibly high-fructose corn syrup, HFCS). Sucrose is 50:50 glucose and fructose, and HFCS is usually presented with a similar ratio.

The relevant mechanism is that fructose is metabolised by liver cells (hepatocytes) and although there is a pathway by which glucose can be produced from fructose, most fructose ends up as fatty acids (see link). Carbohydrates coming from bread, rice, pasta and all the usual suspects are almost entirely glucose, and glucose can enter the blood and go straight to the working muscles.

[Link; the metabolism of glucose and fructose in liver hepatocytes]

http://physrev.physiology.org/content/physrev/90/1/23/F2.medium.gif

High fructose consumption can result in inflammation of the liver and eventually non-alcoholic fatty liver disease. A liver in this state has a reduced ability to extract lactate from the blood and convert it back to glucose. This presents a rate-limiting factor. If lactate can only be removed from the bloodstream at a certain rate (by the liver) then lactate can only be added to the blood at a certain rate (by working muscles). This means your power output will be reduced i.e. a lower AT.

However, if you are young, active and healthy I think it is pretty unlikely that you will have liver inflammation to the extent that it affects performance. You would need to ask your doctor for a liver panel to check the markers for liver damage.

As for forcing your body to "find and consume more aerobic based energy sources", that's the goal of standard training (high mileage, long runs, threshold runs, you know them all I'm sure). You can use fasted and low-carb methods to help do this but it's certainly not necessary.

I'll stop writing now. Hope there is something in there that is helpful.

thanks for your great response.

the sugars I am talking about is in addition to the more simple sugars from my normal carb sources. corn syrup, yes! fructose.. most likely. cakes, chocolate, brownies, ice cream... not too much candy but some.

some more background: I am 41, my past: was jr nat team, national college champ, and raced professional for triathlon. 20 years in that sport. no, I didnt race the brownlees (I did race simon lessing, spencer smith) all while eating terribly. have not trained / raced seriously for some time but last year did an uphill TT race on the bike. a 75 minute effort at LT and I was not holding up well.. was tying up (swimming term) every time I tried to hold my LT, I couldn't and had to keep backing off. was ridiculous and packed with lactic acid. training was ok leading up to it. lots of hill repeats and some longer sustained efforts. diet was torrid, per usual. one race out of the blue, with moderate training, no real indication, I know. but training was much better than that day would indicate.

wondering if I have done permanent liver damage after years of crap food like you said?

I had a liver panel before and no crazy numbers so I should be good. I have recently (last year) discovered i have high uric acid levels (gout) and am taking meds to stay in the normal range. not sure how this may change things lactic acid wise? or how diet plays in?

I chalk a lot of it to, I am not the athlete I was, nor is the training. would like to be competitve as a geezer though, if I were to go that route.

Why are you responding to yourself?

More likely to have an impact on insulin production and regulation, and blood glucose levels?

If you are a triathlete then you surely know Joe Friel. If you have not already done so you could read about his experiences. As a master he overhauled his diet and reckons he saw improvements to his performance as a result.

As I said before I think it is pretty unlikely you have done liver damage if you have been highly active. Non-alcoholic fatty liver disease is usually seen in sedentary fatties who eat crap, not serious athletes.

true, but sedentary fatties aren't concerned with sports performance. and we want any edge.. joe friel wrote the periodization bible for tri geeks. I know him more than you could possibly imagine..

what do you mean "aerobic based energy sources"? the choice between aerobic or anaerobic use of the glycolysis end-product pyruvate (and thus lactate production) is based upon oxygen availability, not presence or absence of substrate.

sugar fiend galore wrote:

is it foolish to think that by having less sugar to burn, your body is forced to find and consume more aerobic based energy sources (fat/protein via O2)?

ymcmb wrote:

what do you mean "aerobic based energy sources"? the choice between aerobic or anaerobic use of the glycolysis end-product pyruvate (and thus lactate production) is based upon oxygen availability, not presence or absence of substrate.

sugar fiend galore wrote:

is it foolish to think that by having less sugar to burn, your body is forced to find and consume more aerobic based energy sources (fat/protein via O2)?

I think it's pretty clear he is referring to non-glycolysis pathways i.e. fat and protein metabolism. The former producing no lactate and the latter very little if any.

The production of lactate from pyruvate does not create an acidic condition. The conversion reaction of pyruvate to lactate actually CONSUMES hydrogen ions. What produces hydrogen ions is ATP hydrolysis (breakdown.) The reason you become acidic at high intensity is because you have massive ATP hydrolysis rates, and produce more H+ than can be quenched by buffers. You also happen to produce lactate at high intensity, but it is an independent reaction from hydrogen ion production. And lactate does not contribute to fatigue.

So, if you consume less carbohydrate, you may produce less lactate, but you'll still produce an acidic condition from ATP breakdown, and that will contribute to fatigue.

Rod Munch wrote:

And lactate does not contribute to fatigue.

You sound like you know your stuff. Are you sure that lactate does not contribute to fatigue? I was under the impression that there is a feedback mechanism for blood lactate. Do you know if I am mistaken?

Good post, thanks.

Thanks. It's fairly well known (but not well disseminated in textbooks and public forums) that lactate does not contribute to fatigue. Lactate is converted to pyruvate or glucose and used as fuel. It just happens that protons (hydrogen ions) are also produced when we produce lots of lactate (intense exercise), so lactate always gets a bad rap. Take a look at this article for some great info on the subject:

http://www.ncbi.nlm.nih.gov/pubmed/15308499

It's not impossible that years of bad eating have led to plaque buildup in your coronary arteries, which hurts performance. If the fire's hot enough anything will burn, but the furnace will still go to shit.

Athletosclerosis wrote:

It's not impossible that years of bad eating have led to plaque buildup in your coronary arteries, which hurts performance. If the fire's hot enough anything will burn, but the furnace will still go to shit.

Explain how sugar causes plaque buildup. Explain how plaque buildup affects athletic performance.

Do you think you body distinguishes "refined" sugars from any other source of carbohydrate when it comes time to metabolize stored glycogen?

odo wrote:

Explain how sugar causes plaque buildup. Explain how plaque buildup affects athletic performance.

Q1: Adverse effects on HDL, LDL, and triglycerides, plus blood pressure

Q2: Coronary artery disease limits the blood supply to your heart, impairing performance to some degree. Eventually this will cause heart pain and exhaustion when you exercise, if you're lucky.

Athletosclerosis wrote:

odo wrote:

Explain how sugar causes plaque buildup. Explain how plaque buildup affects athletic performance.

Q1: Adverse effects on HDL, LDL, and triglycerides, plus blood pressure

http://archinte.jamanetwork.com/article.aspx?articleid=1819573http://www.heart.org/HEARTORG/GettingHealthy/NutritionCenter/HealthyEating/Added-Sugars-Add-to-Your-Risk-of-Dying-from-Heart-Disease_UCM_460319_Article.jsp

Q2: Coronary artery disease limits the blood supply to your heart, impairing performance to some degree. Eventually this will cause heart pain and exhaustion when you exercise, if you're lucky.

The first link doesn't support your statement. Considering that, do I even need to look at the 2nd link?

Where are the links supporting q2?

Rod Munch wrote:

Thanks. It's fairly well known (but not well disseminated in textbooks and public forums) that lactate does not contribute to fatigue. Lactate is converted to pyruvate or glucose and used as fuel. It just happens that protons (hydrogen ions) are also produced when we produce lots of lactate (intense exercise), so lactate always gets a bad rap. Take a look at this article for some great info on the subject:

http://www.ncbi.nlm.nih.gov/pubmed/15308499

My question was poorly worded. I know the biochemistry and realise that lactate does not cause fatigue in the manner often taught in the classroom in recent decades. I was referring to teleoanticipation/central governor models whereby the brain monitors blood chemistry and neural information, and power output is moderated and energy is meted out as per the expected remaining duration of the event.

Lactate is the end product of glycolysis (blood sugar to lactate) and glycogenolysis (muscle glycogen to lactate).

Lactate is an essential pathway in carbohydrate metabolism, it has nothing whatsoever to do with fatigue, because it is an essential energy source.

glycobabble wrote:

Lactate is the end product of glycolysis (blood sugar to lactate) and glycogenolysis (muscle glycogen to lactate).

Lactate is an essential pathway in carbohydrate metabolism, it has nothing whatsoever to do with fatigue, because it is an essential energy source.

I would argue that pyruvate is the end product of glycolysis (and glycogenolysis). Whether pyruvate goes to lactate depends on several factors.