What is Fitness? Part 3: Competency in 3 Metabolic Pathways


In our previous articles we have summarized CrossFit’s first 2 standards to evaluate fitness – the 10 General Physical Skills and capability at random physical tasks.


Here we will discuss the 3rd and final standard in more detail: competency in the 3 metabolic pathways.


Metabolic Conditioning

Biking, running, swimming, rowing, and jumping are understood as “metabolic conditioning,” often referred to as “cardio.”


All cardiovascular efforts can be categorized as one of the 3 metabolic pathways.  These pathways are the Phosphagen pathway, the Glycolytic pathway and the Oxidative pathway.


The Phosphagen pathway dominates the highest-powered activities, those lasting up to about 10 seconds.  The Glycolytic pathway dominates moderate-powered activities, those lasting up to several minutes.  The Oxidative pathway dominates low-powered activities, lasting in excess of several minutes.


[graphic] “energy systems”


The first two metabolic systems, Phosphagen and Glycolytic, are considered “Anaerobic” while the third, Oxidative, is considered “Aerobic.”


Highly and moderately powered efforts lasting up to a few minutes are anaerobic, while low powered efforts lasting more than several minutes are aerobic.  Good examples of these can be seen in Track meets.  The 100m, 200m, 400m, and 800m events are largely anaerobic, while the 1,500m, mile, 2,000m, and 3,000m are largely aerobic.


Anaerobic Training

Anaerobic training – high and moderately powered, quick efforts – is unique in its capacity to dramatically improve power, speed, strength, and muscle mass.  It also greatly benefits cardiovascular function and decreases body fat, even better than aerobic training.


In fact, anaerobic training will also help develop aerobic capacity, where the inverse unfortunately is not true.  Many endurance athletes recently have implemented anaerobic (sprint/explosive) training, and seen immense improvements in their performances.  Greater muscular development and comfort at a higher heart rate will make endurance events simpler.


Aerobic Training

Aerobic training, lower powered longer lasting efforts, benefits cardiovascular function and decreases body fat.  It helps vastly improve 2 of the 10 General Physical Skills, Cardiovascular/Respiratory Endurance and Stamina, and is beneficial to many sports.


Unfortunately as a sole focus, aerobic training is inferior to anaerobic training for an individual concerned with total conditioning and optimal health.  This is evident at any elite level track meets.  Pay attention to the physiques of the sprint athletes and the distance athletes.  The difference you’ll notice is a direct result of training at those distances.


Balance & Training

Well rounded, overall fitness, which CrossFit promotes and develops, requires competency and training in each of these pathways.


Balancing the effects and adaptations of these determines the metabolic conditioning or cardiovascular training that we implement in CrossFit.  It is important to be able to run 2 miles at a consistent and strong pace, while also being able to sprint 100m at a full effort.  Each have their own benefits and place in a person’s metabolic abilities.


The more you train with a constant variance, the more well rounded, and optimally fit, you will become.

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