Re: links re lactic acid, lactate and carbohydrates

[Guest guest]

Thanks, Barbara. I will try to digest this in the next bit of time. I

am very slow putting so many different concepts into my brain. For the

moment the connection I am making is maybe I can reduce my lactate load

by reducing my carb intake. Overly simplistic, I am sure, but that is

where I am. Again, thanks Barbara!

Regards

Sunny

> http://tkdtutor.com/11Training/LacticAcid.htm

>

> http://www.cytosport.com/science/lacticacid.html

>

> http://members.shaw.ca/bodybuilding/Muscles/Lactic_Acid.html

>

>

> Did a little searching this afternoon and these links and others

> helped me

> understand the connection between glucose and lactic acid. Note that

> most of

> the experts on these sites are talking about normal metabolism in

> athletes,

> but the basics were very helpful and there is some mention of excess

> lactic

> acid or lactic acidosis and one mention of mitochondria. (pasted

> below) 

>

> Most of these articles were authored by university professors, either

> biochemistry or exercise physiology and the information all seemed to

> jive.

> So I think they are reasonably accurate.

>

> Several sites were trying to dispel " myths " among athletes about

> lactic

> acid.

>

> There's quite a bit about pyruvate too and its role.

>

> I also learned there is something called the Cori cycle whereby lactic

> acid/lactate is recycled by the liver into glycogen via

> gluconeogenesis.

> This was one of those aha! moments because I know that

> gluconeogenesis is

> impaired in people with CPT deficiency. But the " backward " Cori cycle

> also

> allows for the utilization of carbs without a large surge of insulin.

> Very

> interesting.

>

>

> Some highlights:

>

> The body produces lactic acid whenever it breaks down carbohydrates

> for

> energy.

> The faster you break down glucose and glycogen the greater the

> formation of

> lactic acid. At rest and submaximal exercise, the body relies mainly

> on fats

> for fuel. However, when you reach 50% of maximum capacity, the

> threshold

> intensity for most recreational exercise programs, the body " crosses

> over "

> and uses increasingly more carbohydrates to fuel exercise. The more

> you use

> carbohydrates as fuel, the more lactic acid you produce.

> --------------

>

> Approximately 75% of the lactic acid made during exercise is used as

> fuel.

> The remaining 25% is converted to glucose in the kidney and liver. The

> removal of accumulated lactic acid helps avert excessively high

> levels, and

> the conversion of lactate into glucose helps maintain sufficient

> levels of

> blood glucose, which is important during prolonged exercise.

> -------------------------

>

> Lactic acid starts to accumulate in the muscles once you start

> operating

> above your anaerobic threshold. This is normally somewhere between

> 85% and

> 90% of your maximum heart rate (MHR).

>

> If your lactate threshold (LT) is reached at a low exercise

> intensity, it

> often means that the " oxidative energy systems " in your muscles are

> not

> working very well. If they were performing at a high level they would

> use

> oxygen to break lactate down to carbon dioxide and water, preventing

> lactate

> from pouring into the blood.

>

> If your LT is low it may mean that:

>

> ---you are not getting enough oxygen inside your muscle cells

> ---you do not have adequate concentrations of the enzymes necessary to

> oxidize pyruvate at high rates

> ---you do not have enough mitochondria in your muscle cells

> ---your muscles, heart, and other tissues are not very good at

> extracting

> lactate from the blood.

> -----------------------------

>

> Why this backward path for liver glycogen formation? Lactate is

> removed much

> more rapidly from the circulatory system than glucose, which

> expedites the

> disposal of dietary carbohydrate without a tremendous insulin surge

> and

> stimulation of fat storage.

> -----------------------------------

>

>

>

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