Time for our Workout Of The Month. Each month we take a look at a different exercise and break it down by movement, how to do it, and discuss some of the positive versus negative impact that it can have to you and your level of fitness. Some workout’s of the month breakdown how to do a common exercise, others feature a specific exercise. This month is part two of a series exploring anaerobic versus aerobic exercise. Last month was aerobic exercise. This month we explore anaerobic metabolism and how it pertains to fitness.

What Is Anaerobic Exercise?

Anaerobic is activity created without the presence of oxygen. Oxygen is almost a necessity for most activities lasting longer than thirty seconds – however, a number of activities only last a number of seconds and don’t need oxygen. These type of activities are anaerobic – or without oxygen. Just like with aerobic exercise, the primary source of energy is still from adenosine triphosphate, or ATP – the cellular structure necessary for muscle contraction. For aerobic exercise, the ATP generating pathway is an oxidative pathway. There are two pathways for energy for anaerobic exercise:

The ATP-CP Pathway:

In this pathway, ATP is joined together with creatine phosphate (popularly used as a supplement in the gym with the theory that the more creatine phosphate available, the faster ATP will regenerate). This ATP-CP pathway provides energy for high-intensity, short duration bouts of exercise or activity lasting for up to about ten seconds of activity. Enzymes in your body cause the phosphates to be released to provide energy. The muscles then use the breaking of the phosphate bonds for energy. Pretty simple, eh? This pathway is the first to be activated, regardless of the type of physical activity you’re doing. It’s the most available source of energy, however, it only has a small amount of ATP and CP available within the cells of the body so it’s also the quickest to run out.

Type Of Anaerobic Exercise For The ATP-CP Pathway:

High intensity short duration activity such as heavy weight training lasting approximately up to ten seconds. This type of pathway will supply energy for the heaviest most powerful lifts – but only for a few repetitions before the pathway is depleted.

Glycolysis Pathway:

The next pathway for anaerobic exercise is the glycolysis pathway. This system uses the breakdown of carbohydrates to produce ATP. In this system one glucose molecule will produce two ATP. Although this type of activity produces more energy than the ATP-CP pathway it’s only limited to about thirty to fifty seconds of activity.

Type Of Anaerobic Exercise For The Glycolysis Pathway:

This is probably where most exercise occurs in the gym. Here’s you’ll find your moderate activity of people pushing weights for about eight to twelve reps before the body expends its energy. At that point, weight will have to be lightened. After about that point the muscle become fatigued and the workload has to be lessened before the body converts to a longer lasting, aerobic exercise.

Food Sources For Anaerobic Activity

The main sources for anaerbic activity come from sugars that have been stored up in the muscles and creatine-phosphates that have been stored up in the body – and now you know why people use creatine supplementation. The theory is that there will be more available creatine in the body to replenish used energy sources. Eventually, as sugar stores and creatine supplies are used up, performance will be impaired. In other words, good luck going through bouts of sprinting for hours on end with the same levels of intensity.

Energy Differences Between Anaerobic Exercise vs. Aerobic Exercise

As you can see, the amounts of energy created by each energy pathway differ greatly. The ATP-CP pathway generates one ATP, the glycolysis generates two ATP, and the aerobic pathway creates about thirty-six ATP.

Generally, the aerobic activity is much more sustainable for longer periods versus the anaerobic activity which is used for strength training, power training, sprinting, and weight training lasting of reps for about less than fifty seconds with a heart rate that runs at 86% to 90% of your max heart rate (220 minus your age).

Hopefully you can use this information to help you structure your workouts accordingly. Just remember, all types of activity start out being anaerobic before converting to aerobic activity.

Questions about anaerobic or aerobic metobolism? Let us help you – leave a comment.


Clark, M., Corn, R., Lucett, S. NASM Essentials Of Personal Training. National Academy Of Sports Medicine. Baltimore: Lippincott Williams & Wilkins. 2008. Print. 51-51. 432.