Metabolic Pathways-Rest Day


CrossFit’s last fitness standard covers the three metabolic pathways/systems or ‘engines’ that provide energy for all human action and activity.

  • Phosphagen pathway – dominates the highest powered activities which require maximum power output and effort. Each effort within this pathway last anywhere between 1-10 seconds in duration. 1/3/5 rep heavy max lifts are examples of this pathway.
  • Glycolytic pathway – dominates moderate powered activities that last up to several minutes in duration of effort. Tabata intervals; max reps of push ups in 2mins; ‘metcon’ type WODs, are great examples.
  • Oxidative pathway – dominates low powered activity which last in excess of several minutes. 5K run or row; long distance swimming etc.

The total fitness that CrossFit is after, aka GPP or general physical preparedness, is exactly what we are promoting and developing. This requires us to be adept and competent in each of these three pathways. Depending on how we choose to utilize each pathway within a workout will determine the type of stimulus and effect we are attempting to illicit.

Many of us, especially non-CrossFitter’s, favor one or two to of these pathways and strictly stay within that system for the majority of our training. What this inevitably does is blunt our goal in achieving the general ‘total’ fitness we are after. If we train too long in one pathway, then we are technically specializing, vice attempting to become good at all three and gradually raising our bell curve across the board (does ‘increasing work capacity’ sound familiar?). Doing nothing but lift heavy weight will make us strong & powerful, but will decrease our endurance/stamina capacity; running solely long distances will degrade our strength and explosiveness; working strictly on bodyweight calisthenics at the expense of other modalities will ensure that we are one dimensional.

Knowing & understanding these pathways is the key to achieving competency in the 10 general physical skills we covered last week. By varying these systems, we improve and increase our strengths across the board which in turn will improve and increase our capacity to prepare for the unknown & unknowable. In this case, it is better to be a jack-of-all trades rather than a master at one…at least when it comes to our definition of fitness.

The sole motivational drive for these three pathways is simply to ensure we are broad and general in our quest to achieve our goals. The more we vary and change how often we train in these pathways, the more well rounded we become.


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