I often joke that I fear the oxidative cycle. (In fact, I want a t-shirt that quotes me.) So, why might I say this? For two main reasons: I’m a terrible endurance athlete, and more importantly, I believe the most effective fitness gains occur in the anaerobic system.
Our bodies have three metabolic pathways that can be broken down into two cardiovascular systems: Aerobic (oxidative pathway) and anaerobic (phosphagen and glycolytic pathways). Each of these energy systems have their own special characteristics. Aerobic training allows athletes to work at lower intensity levels over extended periods of time, decreasing body fat while also increasing cardiovascular endurance and stamina. Many long-distance runners and ultra-endurance athletes fall into this category of training. Aerobic workouts are commonly referred to as “cardio”. Anaerobic training allows us to exert great effort over short durations. During this intense time period, our bodies improve in power, speed, strength, and muscle mass, while also burning fat.
On the surface, it might appear that the 2 cardiovascular systems are the same, but actually, they differ drastically. For example, aerobic activity has a pronounced tendency to decrease anaerobic capacity. Athletes who train this way extensively experience decreases in muscle mass, strength, speed and power. Conversely, anaerobic conditioning promotes power, speed, muscle mass, strength and fat loss. Moreover, when implemented properly, anaerobic conditioning can be used to develop a very high level of aerobic fitness without the muscle wasting effects.
The high intensity is where all the work is done and where if performed correctly, all of the “benefits” are made, while the lower intensity is there to stimulate recovery and have you catch your breath.
As CrossFitters, our ultimate fitness goal is general physical preparedness (GPP). This desired outcome combines power, strength, speed, and muscle mass along with a strong cardiovascular capacity to quickly move large loads over long distances. In order to reach this ultimate goal, we must train the two metabolic pathways that most effectively support the growth of GPP. These pathways, the phosphagen and glycolytic, support sprint and mid-distance activities lasting 10-30 seconds and 30-120 seconds, respectively. Many of us are familiar with some well-known CrossFit benchmarks (think “Murph’) that take most athletes more than 40 minutes to complete and are grueling endurance WODs. However, constantly training these long endurance WODs that target only the oxidative pathway does little to benefit our overall goal of GPP.
Targeting the phosphagen and glycolytic pathways (anaerobic) enables athletes to increase not only power and speed while burning fat, but also overall endurance. So, rather than having our athletes complete “Murph” every week, we primarily target these two pathways with shorter, more intense workouts in order to get the “most bang for our buck” in terms of training time and improved work capacity.
By constantly varying functional movements of the three main fitness activities of CrossFit (gymnastics, weightlifting, metabolic conditioning) and performing these movements at high intensity, we effectively target these pathways and build both our anaerobic AND aerobic capacities – forging better CrossFitters in the process.
If anyone wants an “I fear the oxidative cycle.” t-shirt, let me know.