Lactic acid system

• the lactic acid system is also called anaerobic glycolysis
• it breaks down glucose to provide energy to resynthesise ADP into ATP
• the process uses coupled reactions

GLUCOSE:

• supplied from digestion of carbohydrates / glycogen
• readily available as an energy fuel

Anaerobic glycolysis:

The partial incomplete breakdown of glucose into pyruvic acid

Decrease in PC stores

activates enzyme phosphorylase

glycogen broken down into glucose

broken down further in glycolysis reactions

takes place in muscle sarcoplasm, does not require oxygen (anaerobic)

PFK Phosphofructokinase breaks glucose into pyruvic acid 

Pyruvic acid is further broken down into lactic acid by the enzyme lactate dehydrogenase LDH

One mole of glucose is coupled to resynthesise two moles of ATP

• slower and more complex than ATP/PC system
• still quick process < not dependent on oxygen
• provides energy to resynthesise ATP in first 2-3 mins of high intensity short duration anaerobic activity
• during flat out activity system will last up to 30 secs

OBLA Onset of Blood Lactate Accumulation

As lactic acid accumulates

pH decreases

glycolysis enzymes are inhibited

breakdown of glucose is prevented

muscle fatigue induced

Energy released from glycogen/glucose during anaerobic glycolysis is not used for muscular work.

It is used to resynthesise ADP back into ATP in a coupled reaction.