As the festive season is well and truly upon us, it goes without saying that most of us, even with the best of intentions, will end up over-indulging on food and drink. So in anticipation of the new years’ “rush” I thought I’d finish the year with a fitness training article. Here’s the lowdown on the body’s aerobic and anaerobic energy systems – what they are, how they work and which is best way to workout for you. Merry Christmas everyone!
Aerobic and anaerobic are simply terms used to describe how the cells within the body produce energy and refer to energy systems. Every movement we make requires energy to be created and there are three main ways that this is done: one with oxygen – aerobic, and two without oxygen – anaerobic.
Aerobic refers to the body producing energy with the use of oxygen. Continuous steady state exercise is performed aerobically. When it comes to aerobic exercise, you would usually think of spending anywhere from 20-90 minutes performing an exercise – this could be on an exercise bike, treadmill or cross trainer or even simply walking and jogging.
The aerobic energy system utilises fats, carbohydrates and sometimes proteins to produce adenosine triphosphate (known as ATP – see my earlier blog post on EPOC here) for energy use. It produces far more ATP than either of the anaerobic energy systems but at a much slower rate, therefore it cannot fuel intense exercise (such as HIIT) that demands the fast production of ATP.
Anaerobic refers to the body producing energy without oxygen. This is typically exercise that is performed at a higher intensity. There are two ways that the body can produce energy anaerobically:
- The ATP-PC system, which consists of adenosine triphosphate (ATP) and phosphocreatine (PC). This provides immediate energy through the breakdown of these stored high energy phosphates. If this energy system is ‘fully stocked’ it will provide energy for maximal intensity short duration exercise for around 10-15 seconds. It provides you with the most power because it produces ATP more quickly than any other system. Because of this it fuels all very high intensity activities but it burns out very quickly. (See also my earlier blog post on EPOC here).
- The Anaerobic Glycolytic system produces a lot of power, but not quite as much or as quickly as the ATP-PC system. However it has larger fuel supplies (essentially a bigger fuel tank) and doesn’t burn all its fuel as quickly as the ATP-PC system, nor does it fatigue as quickly. It is the anaerobic glycolytic system that is associated with the feeling of burning in your muscles due to the build-up of lactate and other metabolites.
Which is the best?
During exercise, energy will be derived from all three of these systems, but the emphasis will change depending on the intensity of the exercise relative to your fitness levels.
Aerobic vs anaerobic training refers to which energy system you are trying to improve during your training session - its structure and intensity will be very different depending on which one you are trying to improve.
Aerobic training will typically fall in the range of 60 – 80% of your estimated maximum heart rate and can be performed continuously for prolonged periods of time. Anaerobic training will fall between 80 – 90% of your estimated maximum heart rate.
- Aerobic training is good for building endurance and improving your cardiovascular and respiratory function. This means that your heart and lungs become stronger and more efficient, enabling you to train harder and longer as your fitness levels improve.
- Anaerobic training is performed at a harder intensity than aerobic exercise, typically between 80 – 90% of your maximum heart rate. It is used by athletes in non-endurance sports to promote strength, speed and power and by body builders to build muscle mass. Muscle energy systems trained using anaerobic exercise develop differently compared to aerobic exercise, leading to greater performance in short duration high intensity activities. It is a great way of really improving your fitness levels once a baseline aerobic level of fitness is achieved.
Have a wonderful Christmas, try not to eat too much, and look forward to a fit and healthy you in the new year!