The Three Main Physiological Systems

In our last blog we introduced the limiters to Elite Athletic Performance. Now we can delve a little deeper into why they each matter to being able to maximize your training. We can break the limiters down to either a supply or utilization limitation. You are the owner of the most complex piece of technology you will ever have, your body.


Your respiratory system is made up of your lungs and the inspiratory and expiratory muscles. They are solely responsible for being able to take in oxygen (O2) and expel carbon dioxide (CO2). This entire gas exchange is primarily done by the lungs. As you breathe in the lungs take in O2 and through a series of alveoli in your lungs is able to dissipate the O2 into your blood cells.

Why is this important?

Primarily we want to understand that oxygen is an integral part of being able to perform your best on race day. Without being able to appropriately utilize the air we breathe we will be at a distinct disadvantage from those that are able to utilize their O2 more efficiently. If you are able to breathe out during spirometry testing a volume of say 8lt/breath and only are capable of achieving exhalation of say 4lt/breath during testing then you aren’t even using 50% of your respiratory capacity. This would severely limit your athletic performance.


Our cardiovascular system is made up of the heart, blood vessels (arteries, veins and capillaries) and the blood. The blood contains vital nutrients and O2 brought in by the Respiratory system. The veins and blood within carry these essential nutrients to all parts of your body and then returns with waste products like carbon dioxide (CO2) so they can be removed.

Why is this important?

Muscular contraction is the end game with athletic performance. The longer you can sustain muscular contractions the better your chances of wining the race. The capillaries are responsible for final delivery of O2 to your muscles which assist in contraction. Proper training can increase the number of capillaries available at the muscle and such can influence oxygen delivery and utilization.


Your metabolism is the process which refers to a breakdown of nutrients and compounds your cells are able to utilize for energy. Your body secretes enzymes to break down food you consume into sugars, proteins and fats. The cells in your body are then able to use these in the different energy systems to fuel (create ATP) athletic performance. You may typically hear things like anaerobic and aerobic when discussing fuel systems. We will delve a little deeper into fuel systems and why anaerobic and aerobic isn’t exactly correct, in the next blog.

Why is this important?

Your mitochondrial density is the most important part and structure of the muscle specific to muscle metabolism. Think of it as having a bunch of nuclear power plants in your body (and by a bunch I mean Millions) which drives creation of ATP. The number of mitochondria within the muscle is vital to the creation of energy that will fuel your performance.

The ability of the human body to supply oxygen and nutrients from the lungs and through the blood to the muscle for utilization is the difference between winning and losing the race. Your body is a complex network where these systems must interact in order to produce maximum energy for athletic effort. It is much more complex than “push harder” or “train more”. While all of these systems are 100% trainable, knowing where your limitation(s) exist has t be the first step. Without appropriate testing you could very well be training a compensator rather than a limiter to the detriment of overall performance.

If you have ever hit a plateau in your training then you have most likely been training a compensator. Stay tuned for more on how we can better focus on limiters to maximize our training and performance.

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