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Lactic Acid and Performance

guss

guss

MuscleHead
Aug 11, 2010
380
179
#1
Plenty of research has swirled around about lactic acid in recent years and now scientists have debunked many of the myths that lactic impairs performance. In fact, now it is believed that lactic acid actually provides another fuel source for working muscles.

Lactic acid may still be behind the burning sensation during intense exercise but new research has confirmed that delayed onset muscle soreness is from the are microscopic tears and trauma to the muscles and inflammation.

Lactic acid was always seen as a by-product of metabolizing glucose for energy and a waste product that caused a burning sensation in the muscles. Now it is seen as another important fuel source in the body. Lactic acid is formed from glucose, and used by working muscles for energy. Now it is thought that muscle cells convert glucose or glycogen to lactic acid. Then lactic acid is absorbed converted to a fuel by mitochondria in muscle cells. By training at a high intensity (lactate threshold training) it is thought that the body creates additional proteins that help absorb and convert lactic acid to energy.
 
AWARE72

AWARE72

MuscleHead
Oct 17, 2010
323
18
#2
Plenty of research has swirled around about lactic acid in recent years and now scientists have debunked many of the myths that lactic impairs performance. In fact, now it is believed that lactic acid actually provides another fuel source for working muscles.

Lactic acid may still be behind the burning sensation during intense exercise but new research has confirmed that delayed onset muscle soreness is from the are microscopic tears and trauma to the muscles and inflammation.

Lactic acid was always seen as a by-product of metabolizing glucose for energy and a waste product that caused a burning sensation in the muscles. Now it is seen as another important fuel source in the body. Lactic acid is formed from glucose, and used by working muscles for energy. Now it is thought that muscle cells convert glucose or glycogen to lactic acid. Then lactic acid is absorbed converted to a fuel by mitochondria in muscle cells. By training at a high intensity (lactate threshold training) it is thought that the body creates additional proteins that help absorb and convert lactic acid to energy.
Yes and lactic acid is then converted to pyruvates and then two pyruvates make glucose, which is then store in the muscle as glucogen. The muscle then uses glucogen and converts to ATP which is your energy source....

Here is a good read on the The Cori Cycle
 
DanButcher

DanButcher

Member
Sep 9, 2010
66
2
#3
So how is lactic acid formed when following a keto diet? Seems like it would be less of an issue due to lack of carbs no?
 
E

eknight

Member
Mar 28, 2013
70
7
#4
I'm not purposefully trying to be disputatious here, but I was taught in all of my bio and A/P classes that the body doesn't actually produce lactic acid (C3H6O3),but instead lactate (C3H5O3),which can not donate the H+ needed to even cause acidosis. Further, it's my understanding that the production of two pyruvates from the final step of gluose breakdown causes absorbtion of two H+'s creating lactate. Because of this, lactate is not the cause of acidosis, but rather, it works as a buffer, being a consequence of acidosis. What am I missing here?

Edit- this article from the AJP validates the above: http://ajpregu.physiology.org/content/289/3/R891.short

"Many physiologists and medical scientists use the term lactic acidosis because of an entrenched sloppy nomenclature within the literature and not an inherent misunderstanding of the mechanism of lactate– production. Nonetheless, in dispelling the myth of lactic acidosis, Robergs et al. (27) take a force-feeding approach and an overt rejection of constructs in general. We feel that this is not warranted and, in fact, is inconsistent within their review. For example, Robergs et al. (27) define a construct as an “unproven, nonfactual interpretation that has mistakenly been accepted as fact.” While constructs may help our understanding of difficult concepts, it should be recognized that usually they are simply qualitative interpretations, which may or may not be accurate, and, for some, they may or may not enhance understanding. In debunking the construct of lactic acid production, Robergs et al. (27) themselves use a number of other constructs that are also not founded on fact to support their arguments. These include the construct of metabolic intracellular nonbicarbonate proton buffering and the construct of cotransport of lactate– and H+. With respect to the latter, consideration of the physical chemistry of water reveals that it is highly improbable that H+ is physically transported and that movement of lactate− alone from one side of a membrane to the other is sufficient to produce the measured H+ responses. Indeed, as long ago as 1920, Jacobs (14) demonstrated that H+ ions do not cross the cell membrane. And yes, pH is also a construct, albeit founded on fact and it can be useful.

In conclusion, it is useful and instructive to accurately follow the path of protons in metabolic pathways. We agree with the data as summarized by others (18, 27, 28) that lactic acid is not produced in muscle and that it is not present in meaningful concentrations. There is merit in providing a useful summary of the underlying biochemical reactions involved in energy production within muscle and in identifying the correct species of metabolic substrates and products. However, failure to apply the entirety of physicochemical principles leads to the incorrect and misleading conclusion that lactate– is unrelated to the metabolic acidosis of exercise. We do contend, therefore, that the accumulation of lactate– within skeletal muscle directly contributes to intracellular acidosis, by virtue of the fact that it is a strong acid anion that fundamentally alters the behavior of water. With respect to acid-base balance, it is inappropriate to consider each biochemical reaction independently, and it is similarly inappropriate to try to link them temporally or in biochemical sequence. Acid-base balance changes instantaneously; therefore, a more complete understanding of the acidosis of exercise considers the simultaneous biochemical, transport, and proton buffering reactions, as well as their instantaneous and simultaneous physicochemical interactions with water, at any point in time. As stated by Norman Jones in 1980 (16): “The simple biochemical relationships above yield only a shortsighted view of proton release because the ionic state of the reactants is ignored. As they may exist in either acidic or basic forms, the net charges need to be taken into account. Reference to a biochemistry text (20) will show that the equations may be written more accurately and the source of protons is not what it seemed at first.”
 
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