LACTIC ACID/DELAYED ONSET MUSCLE SORENESS

Contrary to what many believe, post workout muscle "burn" which occurs 24-48 hours after exercise is not the result of lactic acid buildup, but Delayed Onset Muscle Soreness or DOMS.  DOMS is the natural process the body undergoes in building more muscle.  This explains why we utilize a Hard/Easy sequence in our training and workout routines.  Muscles require recovery time to heal and build.

The buildup of lactic acid has long been associated with an athlete shutting down, or "hitting the wall" in the case of the distance runner.  Lactic acid is produced and builds up during a workout when muscles are unable to get enough oxygen to convert food to energy.  This buildup can create a sharp slowdown in performance.  It is important to note however, lactic acid is gone from your muscles within an hour of exercise.  Studies show that lactic acid actually fuels mitochondria (the cell's power producers) and helps convert energy into useful forms.  An increase in mitochondria allows an athlete to burn more lactic acid and thus allows muscles to work harder and longer.  Endurance training, running longer distances and times, is the key ingredient in increasing mitochondria mass and lessening the impact of lactic acid buildup.

In short, the reason trained athletes can perform harder for longer periods of time is because intense training causes their muscles to adapt to more readily and efficiently absorb lactic acid.  Endurance training, the "long run," has a place in our training plan.  While the result may be DOMS, the soreness is a general indication of the effectiveness of the exercise.