LACTIC ACID

LACTIC ACID

            Many athletes use the feeling of “burning” in their muscles to set the rhythm of their workouts without really

knowing why. We shall briefly describe the cause of this feeling here and explain how it should be understood.Among other things, the metabolism of energy produces cellular oxidation; this mechanism releases hydrogen ionsfrom the nutritional substrate due to the action of the enzymes that regulate the process.

           These hydrogen ions are picked up by the coenzyme NAD+. In short, the substrate loses ions as it oxidizes, and

these are gained by the coenzyme, which is reduced to NADH while the other H+ is released into the cellular liquid.

Another receptor, called FAD, acts in a similar manner, bonding with two hydrogen atoms to form FADH2.

As both FADH2 and NADH are transported around the respiratory chain, two hydrogen ions bond with one atom

of oxygen to form water.

           Also, adenosine triphosphate (ATP) is the primary fuel burned by the muscle in short, intense bursts of effort (like

those required by muscle training). The process by which FADHS and NADH are transferred to the molecular oxygen

is called phosphorylation.

In very intense exercises, a deficit of O2 occurs, causing an imbalance between the release of H and its capture by

O2. The hydrogen ions accumulate and bond with the pyruvic acid present in the muscle to form lactic acid (not

to be confused with lactate, a salt), which is in fact a waste product but is recycled back into pyruvic acid by the

body for further use.

          This lactic acid spreads through the bloodstream, moving away from the place where it was created. However, when

an intense effort continues for some time, the system fails to generate ATP as fast as it is needed, and the resulting

accumulation of lactic acid inhibits the functioning of some of the enzymes necessary for muscular contraction,

which slows down or stops.

           The effort involved in a “leg press” series of 3 maximum repetitions (to “failure”) would be enormously intense,

but would take little time. However, if we were to try 15 maximum repetitions of the same exercise, we would

experience a burning sensation and panting, indicating an accumulation and deficient synthesis of the lactic acid.

Having reached this point, you should bring your breathing under control and actively rest the area concerned by

massaging or moving the muscles to stimulate irrigation and the normalization of the body’s systems.

Credit: Encyclopedia of Muscle Exercises