Energy is required for a person to play sports or perform any physical activity. Understanding the Energy systems that are responsible for the sport or physical activity can help increase efficiency and performance. There are 3 main types of energy systems.
Anaerobic A-Lactic (ATP PC)
The Anaerobic A-lactic, also known as the Adenosine Triphosphate (ATP-PC) energy system which contains the Phosphocreatine (PC) stores of muscle cells that is able to sustain very short period of activity. This energy system does not rely on oxygen to act as fuel.
Examples of ATP-PC being utilized are activities that involves short and power bursts (e.g. 100 Meters sprint, power-lifting etc.). It usually up to 10 to 15 seconds and requires a 2-minute rest to replenish. That is why, it is recommended to have at least 2 minutes of rest between sets for strength and power exercises during training for the ATP to replenish, and to prevent going into the Aerobic system.
Since ATP-PC is the primary energy fuel for the first 5 to 10 seconds, to train the Anaerobic A-lactic energy system (Speed), perform with max effort for around the duration of 5 - 10 seconds when training. Training can be performed with an interval work to rest ratio of 1:7 up to 1:11. Basically, it means that if you are performing the exercise for every 1 min, your rest 7 mins. Resting less such as 1:7 focuses more on the alactic endurance, while resting more such as 1:11 focuses more on the alactic power output.
Anaerobic Lactic (Glycolysis)
The Anaerobic Lactic energy system, also known as Glycolysis, supplies energy to activities (moderate to high intensity) that lasts from approximately 10 seconds to 2 minutes. Similar to the ATP-PC Energy system, glycolysis also does not rely on oxygen.
Examples of this energy system being used are activities such as the 400m, 800m etc.
However, lactic acid will be produced which will be built up into the bloodstream and muscle cells. Have you ever tried cycling all full speed non-stop, at one point, you will feel your muscles starting to burn as you become more and more fatigue. That is Lactic Acid accumulating.
The Anaerobic lactic system takes over as the primary fuel from 10 second onward to 45 seconds, hence, max effort should be performed during this period to train this energy system. Maximum effort above 1 minute should be avoided, as that would be going into the aerobic system. In this phase, interval training would be done with the work to rest ratio of 1:3 to 1:6. Resting less such as 1:3 focuses more on the lactic endurance, while resting more such as 1:6 focuses more on the lactic power output.
The Aerobic Energy system supplies energy for activities that are low in intensity, lasting from approximately 2 minutes to a couple of hours. This energy system is different than the other 2 as it utilizes oxygen to sustain.
The Aerobic energy system is usually used in long and continuous events such as the marathon, long distance swimming etc. This energy system becomes the primary fuel after 1 min onward. Training is usually done with long runs and shorter recovery time. Interval training can also be done with a work to rest ratio of 2:1, focusing on the endurance aspect. Interval training is especially good for intermittent sports whereby you need to constantly run-stop-run-stop, such as basketball.
However, most of the sports do not actually rely just on one energy system. Usually, there will be a mix of all the different energy systems, which 1 or 2 serving as the predominant energy system.