This is the first in a series of blog post based around conditioning in CrossFit. Conditioning has become one of those words that gets thrown around a lot and is a very broad term that needs to be broken down in order to fully understand its components. This first blog post will break it down, and subsequent posts will go into more detail about how we develop it.
Conditioning is generally a term used to describe a training piece that is intended to develop either your aerobic or anaerobic capacity, and the key to designing programmes that develop conditioning is an understanding of the body’s energy systems. The primary function of all the body’s energy systems is to resynthesise ATP. ATP is essential for muscle contraction, and is finite, meaning it will run out if the body doesn’t reproduce it.
The aerobic energy system is the body’s primary source of energy, and uses readily available oxygen to resynthesise ATP within cells. This is a great continuous source of energy but it is a bit slow, so can only be used during low to moderate intensity exercise. What do we class as low intensity exercise? Any exercise that is below your lactate threshold, typically around 70% of your max heart rate, and is relatively long in duration. In CrossFit terms, think 10k row, triathlon style events or long runs.
The anaerobic energy system plays a big role in most CrossFit workouts, and can be split into the lactic or glycolytic energy system and ATP-PC system. For the time being we will focus only on the lactic energy system. This energy system uses blood glucose, and glucose stored in muscle cells to resynthesise ATP through a process called glycolysis. No oxygen is required making ATP production much faster, however oxygen is required to remove the waste product of glycolysis – pyruvic acid. Oxygen reacts with pyruvic acid to again resynthesise ATP and provide more energy, a by product of this second reaction is lactic acid, a build up of which can significantly impair muscle function. So it is the job of oxygen to break down lactic acid and reduce the decrement in muscle function, easier said than done! As ATP is resynthesised faster through the lactic energy system it can fuel workouts that are performed at a much higher intensity than the aerobic energy system, again in CrossFit terms think Fran or Grace.
Now it’s important not to think of these energy systems as stand-alone sources of energy. Your 15-minute AMRAP is too long to be performed using purely the lactic energy system, but your likely to be working at an intensity higher than 70% of you max heart rate. Energy systems are constantly interacting, as one becomes exhausted another takes over, therefore it is important not to focus solely on one or the other. To be a well-rounded CrossFit athlete you need to have well developed aerobic and anaerobic energy systems. Over the course of the next couple of articles we will first look at how to effectively develop each energy system, and then look at how we prioritise, integrate and maintain each energy system over the course of a season.
In summary –