Don’t Forget to Get Glycolytic, Y’all


Remember the metabolic pathways? Yeah, that’s the graph one. The Cliff’s Notes is simply that human bodies operate in one or more of the three following energy pathways at any given time: phosphagen, glycolytic, oxidative.

A true GPP program will, according to CrossFit, develop capacity across all three energy systems. In addition to the metabolic pathways model, the program will cover the basics of the 10 general physical skills, provide a capacity to excel in the hopper model and develop a fitness that repels measurable sickness.

To be honest, it’s this section of the CrossFit ethos that first got my attention. There was purpose. To this day I think it’s beautiful logic.

With regards to the metabolic pathways model, I fear, however, that many programs are missing the glycolytic pathway, at least more so than they think. Now, before I continue, I want to throw a caveat out there that the human body often operates in a combination of energy systems. In addition, part of what determines the energy system in use is the athlete. For example, one can make a 400-meter run glycolytic in an all-out effort, while another athlete may not have the physical fitness to make it anything other than an aerobic one. Nonetheless, I think many programs are missing this middle pathway.

Even the most met-con-biased gyms tend to capture the phosphagen (90 to 100 percent effort between 0 and 15 seconds) pathway, if even by default, in strength days/sessions. The oxidative pathway (0 to 65 percent effort from several minutes and beyond) is often talked down upon in the CrossFit community, but the truth of the matter is that those 10- and 15-minute AMRAPs are mostly aerobic. Guilty as charged!

Now, sure, a set of unbroken pull-ups inside of longer workouts may have glycolytic elements, but I’m speaking to true glycolytic efforts. “Fran,” for example, may be CrossFit’s easiest example of a glycolytic effort if — and that’s a big if — the athlete makes it so. However, unless it’s scaled to be a largely unbroken sprint, Fran can become mostly aerobic, as well.

Aerobic Fran will get plenty of people fitter, don’t get me wrong. But it may not always capture the essence of a true glycolytic effort.

I’d argue that mixing energy systems is harder than it looks but provides an opportunity to capture some performance that’s potentially left on the table. If you’re a coach or programmer, how can you guarantee that you’re capturing that pesky glycolytic pathway with all of your athletes, beginners included?

— Logan Gelbrich