Cardiorespiratory Endurance

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Cardiorespiratory Endurance

Is defined as a measurement of how well your heart, lungs and muscles work together to keep your body active over an extended period of time.


What I want to talk about is the general population’s (including most general practitioners) idea of “Cardio” and how performing these “Cardio” exercises work to make you a healthier human.


Go walk, jog, run, hell do anything for a least 20mins a day. “Got to get your cardio in”, is an all too often blanket prescription from anyone who knows anything about fitness. From the internet Blogger to your overweight family doctor this go do anything approach, although better than nothing, is misleading and often ends up with the person back on the couch.


What do I prescribe and believe in? Well that’s easy to describe in one word.. CrossFit. But where is the cardio in CrossFit? Well it is every time your heart and respiratory rate increase above a resting state. So when and for how long are you doing cardio in a CrossFit class? Well by that definition, the whole time.


CrossFit = Cardio = Energy Systems


The science is often overlooked and unexplained, but if you really want to get into it keep reading.


There are actually 3 different energy systems that we aim to train. They are the phosphocreatine, glycolytic, and oxidative systems of energy production/utilization. It is necessary to train all three of these in order to build the most well rounded individual possible. Here is the reason why.


The phosphocreatine system (under 12 secs) is only for instantaneous, short bursts of maximal energy. A 10m sprint, high jump, throwing a ball, or 1-3RM would be examples of training or using this energy system.


The glycolytic system is the next system in line and picks up after the first 12secs to continue supplying energy for up to 30secs in duration. Think of an all out sprint on the airbike. First you hear a loud roar as the sprint starts and right at the 10sec mark it turns into a low hum as your body switches gears. Training this pathway requires a little longer weightlifting set, 30sec intervals, or sprint repeats for example.


Now we finally get to the last and longest pathway often referred to as “Cardio”. The oxidative energy system which powers our body after the other 2 systems expire. This system is used for everything else from a mile to a marathon, long CF WODs and everyday activities. This is a low intensity workout, and the pathway that by design gets most of the work as it is the default energy system used for our everyday lives.

So if it gets all of the work throughout the day, why do we want to train it in the gym too? We that is a simple answer, comfort! The training required to utilize the other 2 systems can really suck! So the answer is avoid the pain, just go a little longer on the walk, jog or run, and everything will be ok. WRONG!


Be strong for life! You never know what life might throw at you! A natural disaster where you have to sprint, jump, throw, or carry a loved one quickly to safety. A terrorist or animal attack. Even the ability to react quickly enough to catch yourself safely when you trip and fall. These are just a few examples of why train the other systems. There is also a pile of research concerning the carry over benefits for improved health markers, fat loss, and increased energy when training the phosphocreatine and glycolytic energy systems.


So where do you go from here? Hopefully you get into a CrossFit or similar class and go hard as you can on the sprint days! Let the suck factor stay high, and realize that nothing good in life is free, or easy! See you in the box.


-Coach Jeremy

author: admin