why is lactic acid formed even when an athlete is breathing oxygen?

Answer 1

Lactic acid fermentation, as you probably know, is the product of anaerobic respiration in the muscles and other parts of the body. This typically occurs during exercise. Now, as you've implied, it is probably true that people don't stop breathing so there is oxygen entering the body but not enough to sustain intense exercise. Anaerobic respiration and lactic acid fermentation is a fast and efficient way of getting energy to the muscles, even if the consequence is lactic acid build up and a lower amount of ATP. If the muscles and other parts of the body need the energy fast, lactic acid fermentation is the key.
This is a really great website which talks about lactic acid, the good and the bad:
http://www.delano.k12.mn.us/sitepages/pid1817.php

Answer 2

Lactic acid is part of the Krebs cycle in the mitochondria. It is part of the process where the body broduces ATP and stores it in the form of Glucose. When the body is operating under mormal circumstances lactic acid is still formed because it is a necessary stage in the production of ATP. Note this normal production is in the presence of oxygen and therefore it is AEROBIC and produced 36 ATP in cellular respiration where puruvate is CONVERTED TO LACTIC ACID.

Glucose + 2 NAD+ + 2 Pi + 2 ADP → 2 pyruvate + 2 NADH + 2 ATP + 2 H2O

When the body is under stress it requires more oxygen than normally required, if it cannot aquire oxygen quick enough then it will kick into ANEROBIC respiration which is noted by the fromula below.

C6H12O6 + 2 ADP + 2 phosphate → 2 lactic acid + 2 ATP

Note that Lactic acid is now produced more since oxygen is depleted. this is how lactic acid builds up in the muscles.

Answer 3

Lactic acid is formed by the body breaking down glucose and or glycogen, used by working muscles for energy. Lactic acid used to be thought of as a by product of exercising muscles, but is now thought of as another important energy source. So exercise has to be involved, not just breathing for lactic acid to be formed.

Answer 4

Glycolysis is independent of oxygen. Glucose is broken down locally in the muscle to lactic acid faster than the oxidative respiration.

Answer 5

making ATP through the aerobic pathway is efficient but it takes way too long.. when the muscles need ATP NOW they go through fermentation even if there is oxygen. also most of the time you need the ATP urgently is when you are working out intensly and when you are working out really hard your muscles contract a lot and may put pressure on the arteries making it harder for the oxygen to get to its destination