# Lactic acid



## Bigtallfatbloke (12 Jul 2007)

..horrible stuff ...is there a diet or something that can be followed to reduce this stuff and the pain?

Or is it just acase of 'getting used to it' like so many things on a bike?


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## chris42 (12 Jul 2007)

get used to how your body deals with it is how I understand it


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## Blue (12 Jul 2007)

Training isn't supposed to be a way of getting 'used to it' as such - it pushes up the threshold at which lactic acid kicks in.

In my running days I used to think of it as a coal burning fire in the muscle producing power - lactic being the ash which will clog a fire if not cleared. However, if you can get the fire to burn more fiercely there is less ash - so train harder.

I'm not a scientist so my analogy is simplistic. 

However, a science paper by Dr Louis Passfield of the Uni of Glamorgan reported in the July C+ stated that lactic is a partly broken-down carbo molecule that can be used to produce energy and that the pain is caused by nerve endings being stimulated - the article didn't say how to deal with the problem though!


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## Oldlegs (14 Jul 2007)

Lactic acid is produced when muscles cannot get enough oxygen to completely "burn" glucose. As your cardio vascular system improves with training the supply of oxgen goes up = less lactic acid but then you can go faster = more lactic acid. Bit of a Catch 22 really.


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## Fab Foodie (14 Jul 2007)

Oldlegs said:


> Lactic acid is produced when muscles cannot get enough oxygen to completely "burn" glucose. As your cardio vascular system improves with training the supply of oxgen goes up = less lactic acid but then you can go faster = more lactic acid. Bit of a Catch 22 really.



I'd go with that. It also means that (IIRC) only half the energy available per molecule of glucose is released, so burning glucose anaerobically (without oxygen) is inefficient, BUT useful to be able to do for very short high power work. The question was however, what then happens to the lactic acid when sufficient O2 becomes available again (and the burning sensation disappears). The C+ article suggests that when the LA is further oxidised (burnt) it yields the rest of it's energy and that energy is available to do useful work...thus all the potential energy lost when burning glucose anaerobically is regained when sufficient O2 returns. Thus in the long-run, no great disadvantage.


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## Gasman (15 Jul 2007)

> what then happens to the lactic acid when sufficient O2 becomes available again (and the burning sensation disappears). The C+ article suggests that when the LA is further oxidised (burnt) it yields the rest of it's energy and that energy is available to do useful work



More or less. The initial part of glucose metabolism (glycolysis) yields 2 molecules of pyruvate and 2 of ATP (adenosine triphosphate, a cellular energy carrier). The pyruvate is then fed into the citric acid (Kreb's) cycle and electron transport chain which breaks it down further to yield yet more ATP. (I can't remember exactly how much but I'm pretty sure it's more than another 2 molecules).

In the absence of oxygen, the Kreb's cycle won't work and pyruvate stacks up which would stop further glycolysis. The pyruvate is therefore converted to lactate. This yields no further energy but it removes the pyruvate 'block' and regenerates NAD (nicotinamide-adenine dinucleotide, a hydrogen ion carrier) allowing glycolysis to continue.

When oxygen is restored, the lactate is re-converted to pyruvate which then continues on its way through the aerobic pathways.

Although glycolysis releases very little of the energy content of glucose it can release energy faster than the full oxidative pathway at the expense of a lactate build up, hence the reason why you can only sprint for a short period.


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## Keith Oates (16 Jul 2007)

Well that was informative. I try on some rides or commutes to go hard until it's presence is just felt and keep in that state for a while. I don't know if it does any good but it keeps me happy!!!!


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## domtyler (16 Jul 2007)

Sir sir, can I go to the toilet please?


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