Reduction of Lactic Acid in Blood and Muscle

When lactic acid, the product of glycolysis (the anaerobic phase of carbohydrate metabolism), accumulates to high levels in blood and muscle, fatigue sets in. Therefore, full recovery from exercise in which maximal amounts of lactic acid have accumulated involves the reduction of lactic acid levels from both the blood and skeletal muscles that were active during the preceding exercise period.

Several important questions related to this process need answering are (1) how long does it take to remove the accumulated lactic acid (2) what factors influence the speed of lactic acid reduction, (3) what happens to the lactic acid, and (4) what is the relationship between the removal of lactic acid during recovery and the slow-recovery phase.

Speed of Lactic Acid Reduction

Lactic acid is removed from the blood and muscles during recovery exhausting exercise. In general, 25 minutes of rest-recovery are required to remove half of the accumulated lactic acid. The exercise in this case consisted of five 1-minute bouts of pedaling on a bicycle ergometer. Five-minute rest periods were allowed between work bouts. During the recovery period, the subjects (all males) rested while seated on the bicycle (rest recovery). At least 1 hour of recovery was required to remove most of the accumulated lactic acid. The same amount of time was also required following running of rest-recovery are required following maximal exercise to remove half of the accumulated lactic acid. This means that about 95% of the lactic acid will be removed in 1 hour and 15 minutes of rest-recovery from maximal exercise.

The lactic acid concentrations in this example represent average maximal values for both muscle and blood. During submaximal, but heavy, exercise, in which the accumulation of lactic acid is not as great, less time is required its removal during recovery.

To be continued…

Daryl Conant, M.Ed.