Sunday 01.02.11

From Metabolic Conditioning by Greg Glassman (CFJ issue #10)
 There are several metabolic pathways that provide the energy to our bodies, all intertwined and weaved together to form a complicated system, so complicated that they are still discovering pathways. For ease of explanation (and comprehension for me), we will break it down three major metabolic pathways.. These are known as the phosphagen pathway, the glycolytic pathway, and the oxidative pathway. In everything we do, all these pathways are involved in someway, but depending on duration or intensity, determines which pathway is mostly at work.

The first, the phosphagen, dominates the highest-powered activities, those that last less than about ten seconds. Think of a max effort Clean and Jerk or dunking a basketball. The second pathway, the glycolytic, dominates moderate-powered activities, those that last up to several minutes. The 100m, 200m, 400m, and 800m Sprints largely rely on this pathway. The third pathway, the oxidative, dominates low-powered activities, those that last in excess of several minutes. 1500m+ running, swimming, rowing, biking cover those. Interestingly, sitting in a class listening to a lecture, or sitting on the couch watching TV also requires the use of the oxidative pathway.

Complete fitness requires competency and training in each of these three pathways or engines. Balancing the effects of these three pathways is essential to the training we provide at The Compound. Favoring one or two of the pathways at the detriment to any of the others and not recognizing the impact of excessive training in the oxidative pathway are common faults in fitness.  Metabolic Conditioning, or “Metcons” as we refer to it, along with dedicated strength and power workouts, work to train all three pathways and make up The Compound’s version of “cardio”. To understand how this works, we must discuss the interaction of the three major pathways in training.

Of the three metabolic pathways the first two, the phosphagen and the glycolytic, are “anaerobic” and the third, the oxidative, is “aerobic.” Or in simpler terms, just remember that efforts at moderate to high power and lasting less than several minutes are anaerobic and efforts at low power and lasting in excess of several minutes are aerobic. (Again, sprints at 100, 200, 400, and 800 meters are largely anaerobic and events like 1,500 meters, the mile, 2,000 meters, and 5,000 meters are largely aerobic).

Aerobic training benefits cardiovascular function and decreases body fat – all good. Aerobic conditioning allows us to engage in low power extended efforts efficiently (cardio/respiratory endurance). This is critical to many sports. However, there is a cost to training a majority of your time in aerobic conditioning. Athletes training mainly in aerobic efforts witness decreases in muscle mass, strength, speed, and power. It is not uncommon to find marathoners with a vertical leap of only several inches or the inability to lift an 45 lbs bar above their head for multiple repetitions! Furthermore, aerobic activity has a pronounced tendency to decrease anaerobic capacity.

Anaerobic activity on the other hand also benefits cardiovascular function and decreases body fat! In fact, anaerobic exercise is superior to aerobic exercise for fat loss! (Check out Clarence Bass’ article on our favorite Mr. Tabata: Anaerobic activity does, however, improve power, speed, strength, muscle mass and stamina. Anaerobic conditioning allows us to exert a great deal of force for brief time intervals. But on top of all that, anaerobic conditioning does not negatively affect aerobic capacity. In fact, properly structured, anaerobic activity can be used to develop a very high level of aerobic fitness without the muscle erosion common with slower long distance efforts! Look at what the guys at CrossFit Endurance are doing and you’ll see that this method works.

The key to developing the cardiovascular system without an unacceptable loss of strength, speed, and power, and muscle mass is interval training.  Interval training mixes periods of work and rest in timed intervals. We can control the dominant metabolic pathway we want to improve by varying the duration of the work and rest interval and number of repetitions. The Compound's training consists of hitting all the metabolic pathways through 1) Interval training (so we get the cardiovascular benefit of endurance work without the attendant loss of strength, speed, and power), 2) Maximal weight lifting efforts (to increase absolute strength, muscle endurance) and 3) Long distance efforts (to train the skill necessary to survive long bouts).

When preparing for a specific event, you must adjust the pathway you train accordingly.....but only slightly.  For example, for the upcoming Shamrock’N half marathon you will need to shift your focus towards the oxidative.  But properly structured, maintaining balance between the three major pathway, this shift should not have any unfavorable effect to your overall fitness.

For a nice overview of Aerobic vs. Anaerobic check out the CFE FAQ section. cc


  1. 5K run at the track by the prison...29:38 PR!!
    Its been a goal of mine to get a sub 30 min time and I made it!!

  2. Congratulations Matt! Those victories are so, so sweet aren't they??

  3. Way to go Matt !! Wahooey!!

  4. Thanks folks. In the words of " Steffanie"