When you are just about to start your workout and you think I don’t feel very energetic today this could have implications on how you are going to perform, or is it just a figure of speech that we tend to use after a hard day at the office or a late night? To find out the answer to this question today we are going to have a look at the body’s energy systems, which put simply is divided into aerobic and anaerobic, aerobic being when oxygen is used and anaerobic being without oxygen.
The reason why we should all have some knowledge of this is because different exercises require you to use certain energy systems and depending on your goal this will vary the intensity and duration of your workout. We need to train both systems so that we make the most efficient use we possibly can of the appropriate system that is being used at any given time during our workout program or in the performance of our chosen sport.
Whilst the two main energy systems turn on at the same time, one’s prominence over the other depends on the activity being performed.
Aerobic System
As mentioned above this systems requires oxygen, it is a lower intensity type of exercise excellent for improving cardiovascular fitness which in turn is important in the recovery process for exercises of all intensities, another words the more you train this system the quicker your recovery becomes when doing activities that use the other energy systems which we will look at shortly. The aerobic energy system kicks in at 1 min and is still being utilised at 60 minutes plus, those of you who participate in fun runs, half marathons and so on need to train this system.
Other characteristics include the following:
- Does not result in fatigue producing waste products such as lactic acid
- Heart and lungs are critical in this system
- Takes longer to overload than the anaerobic system
- Can be continuous or interval training
Some examples of aerobic activities include walking, jogging, running, rowing, biking, and swimming. Note that high repetition low weight with minimal rest training will also work this system
Anaerobic System
The anaerobic system, is defined as the muscle’s ability to generate energy without the immediate use of oxygen. The anaerobic system comes into play when the energy demand is greater than can be supplied by using the aerobic system. The two main components or pathways of the anaerobic system are the phosphagen system which we will call anaerobic alactic, and the glycolysis system the anaerobic lactic.
The anaerobic alactic provides the majority of energy when you do bursts of high speed or resistance movements lasting 10 seconds and as such is used during short bursts of intense exercise such as sprinting or lifting a heavy weight for 3-4 repetitions. The first 2-3 seconds are supplied by stored energy within the muscle called Adenosine Triphosphate (ATP), the remaining 6-8 seconds are fueled by the breakdown of creatine phosphate, a molecule found in skeletal muscle and also found in the brain providing energy for neurons.
The anaerobic lactic system provides energy when exercise is maintained beyond 10 seconds and up to 60 seconds. The difference in this system is that it produces a by product lactic acid hence the name, the biggest drawback here being that this causes fatigue and the lactic acid needs to be removed which can take some time. You can aid the removal by stretching after the work out and also by drinking lots of water. Rule of thumb for water is 1 litre per 25kg of body weight per day plus 1litre for every hour of exercise.
Another limiting factor of this system is the time it takes for our body to replenish its energy stores. Bringing us to one of the often neglected areas, the recovery period between sets, this is essential particularly when training the phosphate system. Research shows that it can take up to 180 seconds to fully replenish the muscles ATP stores, my experience shows that this can be halved the more training you do in this systems. As I have said in past blogs the body is an amazing system that with use adapts and improves, on the other hand it will quickly do away with areas that are not needed so don’t relent on your training folks.
Some examples of anaerobic activities include sprints, resistance training, power lifting, jumping and high intensity interval training.
Let’s summarise some of the main points in the table below:
| System | Power | Capacity | Fuel used |
| Anaerobic alactic(no oxygen) | Very high | Very low1~10 seconds | Creatine PhosphateStored ATP |
| Anaerobic lactic(no oxygen) | High | Low10~60 seconds | Blood GlucoseMuscle and Liver Glycogen |
| Aerobic(with oxygen) | Low | Very highI min.~60 min plus | Blood GlucoseMuscle and Liver GlycogenFat (Body’s largest energy store) |
The other training variables that need to be taken into consideration here are sets, repetitions, weight/distance and the work/recovery ratio to be used to give you time to recover sufficiently to have the energy for the next set, something that I will cover the next time we talk about this topic.
It’s a difficult topic which I have tried to explain so that you can gain knowledge that will help you achieve your fitness goal, please also consult your sports coach or personal trainer for further clarification, questions and comments are also welcome.
Zol
Fitness Moves