A few weeks back we looked at the overview of energy systems and explained how the body produces energy to meet the demands of a particular environment. This article will look closely at the ATP-PC energy system (Alactic-Phosphocreatine). The ATP-PC system provides a very short explosive power surge.
The ATP-PC system does not need oxygen and is therefore classes as anaerobic work. It is responsible for creating high amounts of force and provides energy to the highest threshold of fibres.
Although the ATP-PC system provides high force, this can only be maintained for around 6-15 seconds. This short time shows how quickly this ATP (Adenosine Triphosphate) depletes in the muscles. As a result, longer periods of reset is required between work. An example of this is within Olympic weightlifting or Powerlifting, whereby athletes can take 5 minutes between lifts to allow the muscular system and nervous system to recover.
(Phosphocreatine + ADP) -> (Creatine Phosphokinase) -> (Creatine + ATP)
The process of creating ATP is complex. The Glycolysis process occurs when phosphocreatine transfers phosphate to ADP. The ATP can be used for muscular contraction.
The storage of the ATP lasts between 2-4 seconds. The resynthesise of ATP will continue for 4-6 seconds until the creatine phosphate within the muscles is depleted.
Training of the ATP-PC system can be achieved by performing short periods of high power work, followed by longer rest periods. A study by Holmyard et al (1994) looked at a group of subjects that performed 6 second sprints with rest periods of between 150-180 seconds. The results of the study showed that there was an 81% recovery in peak power with a 1 minute rest period compared to a 92% peak power output recovery with a 3 minute rest period.
It is important to note that the ATP-PC energy system does not product lactate, however the anaerobic lactic system is at work at the same time. The ATP-PC can produce higher levels of fatigue due to it’s effects on the nervous system. The muscle fibre size and contractile ability must be increased to train the ATP-PC system. Examples include:
- Assault Bike: 15 rounds of 10 seconds Max Effort every 2 minutes.
- Running: 15 x 60 metres with 1 minute recovery.