Energy Systems Part One: Aerobic Energy System

Since indoor cycling’s main focus is on cardiovascular conditioning, we need to use our knowledge of the body’s energy systems to our advantage. In three separate blog posts, I will review these energy systems and how we can focus on them during an indoor cycling class.

Have you heard of Metabolic Training? Well, it’s the term used to describe workouts based on the body’s energy systems. So, we are talking about metabolic training with each post, but I did not want to start with too much terminology right of the bat!

Let’s go back to basics. Our body is an amazing system for generating the energy that allows us to move. Adenosine Triphosphate (ATP) is a substance the body uses to store and move energy. Your cells break down ATP when they require energy. Depending on the energy system, ATP is either formed from the breakdown of glucose with oxygen (aerobic) or without oxygen (anaerobic). This first post will focus on the aerobic energy system.

I like to think of the aerobic energy system (sometimes called aerobic respiration) as the endurance system. Definitely something that is important for us within an indoor cycling class. Our bodies tend to tap into the aerobic energy system after three minutes of exercise (the systems used in the first few minutes will be more the subject of my next posts) and use it as the primary means of energy over the long haul.

The aerobic energy system is able to generate large amounts of ATP but is also relatively sluggish compared to other energy systems. It takes a while to kick in. This is because it involves many steps and continuously requires oxygen and other nutrients. As long as oxygen is available, a muscle cell will continue to use the aerobic energy system as much as possible to contract and relax muscle fibers. Thus, prolonged exercise where the demand on your body does not exceed the ability of this system to provide energy will use the aerobic energy system almost exclusively. In fact, in well-conditioned individuals (like yourself!), the aerobic energy system alone will provide the energy to continue for many hours at a low to moderate intensity!

So how do we apply our knowledge of the aerobic energy system to our drills? Well, let’s look at the appropriate work to rest ratio, which is the time it takes our bodies to recovery from aerobic work. For aerobic work, we must design sessions with the ratios 1:1 (equal parts work and rest) to 1:0.5 (work double the amount of the time we rest).

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