Lactic Acid; not a cause of 'the burn', soreness or waste product.

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   Chris Fryposted 14 years ago

   Lactoc acid (lactate) is widely believed to be responsible for the 'burn' felt when performing strenuous exercise. This however is a fallacy, and the burn is actually the result of an accumulation of hydrogen ions leading to increased acidity (lower muscle pH).
   
   Neither is lactic acid a waste product; it is merely a metabolic byproduct and can be used in the Cori Cycle to fuel further work.
   
   Lactic acid is also presumed to be the cause of soreness felt the next day after intense training. Again, this is simply untrue. Lactic acid is removed from the body within 1 hour of the cessation of exercise, and the soreness felt the next day is due to micro-tears in the muscle fibres (see Delayed Onset of Muscle Soreness).

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2. 70

   Larry Fieldsposted 14 years ago

   Chris Fry wrote:
   "Lactoc acid (lactate) is widely believed to be responsible for the 'burn' felt when performing strenuous exercise. This however is a fallacy, and the burn is actually the result of an accumulation of hydrogen ions leading to increased acidity (lower muscle pH)."
   
   That's spelled "lactic acid", by the way. So, where do all of those pesky H+ ions come from, if not from the lactic acid generated by intense anaerobic muscle activity? The reversible reaction that I have in the back of my mind is the following:
   
   lactic acid = lactate anion + hydrogen cation
   
   Sorry, my computer skills aren't sufficient to type the standard chemistry symbols in this box.

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   1. 60

      Chris Fryposted 14 years agoin reply to this

      I know, simple spelling mistake - see my hub and you will understand I have nearly finished my 2nd of 3yrs of a Bachelor of Science degree.
      
      Firstly, it is important to note that lactic acid is produced whether exercise is being performed or not.
      
      Furthermore Im not stating that hydrogen ions aren't formed from lactic acid - they are (lactic acid does dissociate into lactate and a hydrogen ion). I'm stating that many people widely believe (wrongly) lactic acid to be the cause of the burn, which is not true. This is because lactate is a metabolic precursor for gluconeogenesis, and it is the accumulation of said hydrogen ions which affect the muscle pH, causing the burn.

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