ATP-PC System (Alactic system)
Provides energy through coupled reactions, to resynthesise ADP back into ATP.
PC (phospho creatine) is a high energy compound which stores potential energy.
When ATP levels drop and ADP increases, the release of the enzyme Creatine Kinaseoccurs which breaks down the PC bond (as an exothermic reaction) this energy cannot be used for muscle work but is coupled to resynthesise from ADP to ATP.
this system can work aerobically however it does not need oxygen so can work anaerobically and it takes place in the sarcoplasm of the muscle cells.
can supply energy for 3-10 seconds (100m Sprint)
Lactic Acid Sytem
The break down of glucose to provide energy, through coupled reactions to resythesise ADP back into ATP.
Glucose is supplied directly from carbs or glycogen. the carbohydrated is located in the liver and muscles and are a ready fuel source.
a decrease in PC activates the enyzme glycogen phosphorylase to break down glycogen during the process glycolysis.
takes place in the sarcoplasm of muscle cells and is anaerobic.
during glycolysis the enzyme phosphoructokinase (PFK) initiates the breakdown of glucose into pyruvic acid but if there is a lack of oxygen, pyruvic acid is turned into lactic acid by the enzyme lactate dehydrogenase.
provides energy during the first 2-3mins of high intensity short duration work. if the activity is flat out the la system may only last up to 30secs
Lactic acid continued
the main limitation is the onset of blood lactate (OBLA)
the build up of lactic acid, it inhibits the enzymes involved in glycolysis and thus prevents the breakdown of glucose and brings on muscle fatigue.