Does lactic acid cause muscle soreness or inhibit muscle contractions?

  Actually lactic acid is a good part to muscle contraction as opposed to a bad component as commonly thought of.  It is actually used for energy by the muscles for ontraction/movements in a positive way.  However, its accompanying friend called hydrogen (H+) is the true culprit.  H+ creates the acid base and causes one to have that burning sensation that we commonly associate with lactic acid. 

  High levels of H+ causes us to have that burning in the lungs after sprints, stops the muscles from contracting and all the other uncomfortable feelings that one associates with muscle discomfort.  Lactic acid separates into 2 separate parts, hydrogen and lactate.  Hydrogen (H+) is acidic and gives you that burning sensation in your body (muscles/lungs).   Unfortunately, this is physiologically how the body works and one cannot change the reaction to this. You can build up a higher buffer content of the body to be able to go longer and with stand the discomfort for longer periods but at some point, even highly trained athletes have a breaking point and the muscles will not be able to contract, period!

  Lactic acid is really two separate chemicals one being lactate and the other being H+.  The lactate does not cause muscle soreness, does not cause your muscles too fatigue and does not stay in your muscles for longer than sixty minutes after exercise.

 Muscle soreness is from a variety of anatomical stresses to the body such as: microscopic tears to the muscle fibers, inflammation and edema (swelling) to the muscles because this usually is slow to happen the soreness usually takes 24-48 hrs to set in.  This is why it is typical for a trainee not to feel muscle discomfort/soreness for a day or two after a workout.   Just as if one hit a part of their body, say their leg accidentally, the area does not become immediately swollen, red and bruised.  Usually within hours or days the most severe of the swelling and blood pooling of bruising will set in after, even if ice is  used to reduce the swelling immediately.   Lactic acid has a strong acid base which ionizes and releases hydrogen ions.(225)  This increase in hydrogen ions can impair muscle performance in at least two ways. 

  First, it can reduce the muscle’s ability to produce adosine triphosphate (ATP) chemicals for anaerobic and aerobic production.  Second, hydrogen ions compete with calcium ions for binding to another muscle chemical called troponin for muscle contractions which will inhibit the muscle contraction process.(225) 

So, if you want to avoid muscle soreness some steps to alleviate the potential for severity would be: working out regularly, keeping the intensity not too severe and accepting that the earth is round and soreness can and does happen from exercises this will keep you on the healthy road and moving away from an early retirement from the grave yard!

By:  J.D. Reber

Reference: 

Powers, K, Scott. Edward, T, Howley. Exercise Physiology, Theory and application to Fitness and Performance. 5th Edition  2004