What is The Hype About With Zone 2?
Zone 2 cardio focuses on maintaining a controlled heart rate while accumulating aerobic training volume over time. Popular sports-science figures like Iñigo San Millán and Peter Attia have popularized Zone 2 methodology as a key element to the athletic progression. Typically performed at around 60–70% of VO2 max, Zone 2 training is often described as a conversational pace where breathing remains controlled enough to comfortably breathe through the nose or hold a conversation during the workout. Coming from the high-intensity scope of CrossFit, Zone 2 may not seem beneficial to fitness, but Zone 2 training helps assist the body in converting fat to fuel, builds the aerobic base, and it assists in active recovery.
Zone 2 and The Fat Burning Process
Assessing the body’s exercies metabolic processes, we utilize fat (lipids) as our energy source until we approach efforts that exceed around 80% of our maximum heart rate. Past this point, efforts become anaerobic, and carbohydrates become our primary energy source. This phenomenon of lipid to carbohydrate oxidation is described as the “crossover concept.” It is further confirmed by the respiratory exchange ratio (RER). A ratio near 0.7 is indicative of the Zone 2 conversational efforts, while a ratio around 1.0 assumes that the efforts are becoming anaerobic.
Why Zone 2 Builds the Aerobic Base
Research from ADInstruments notes that an RER of 1.0 is commonly associated with the anaerobic threshold, where carbohydrate utilization and lactic acid build up increase significantly. Lactic acid builds up during the anaerobic process when oxygen becomes limited. Therefore, increasing your Zone 2 capacity increases your threshold to tolerate higher intensities before significant lactic acid accumulation begins, allowing you to sustain harder efforts while remaining primarily aerobic for longer periods of time.
How to Increase Your Zone 2 Capacity
The best way to increase your Zone 2 capacity is through consistent, low-to-moderate intensity aerobic training performed at a sustainable pace. Your local CrossFit gym will have equipment great for Zone 2 training. These include rowers, skiergs, stationary bikes, and fan bikes. Sessions can last anywhere from 30 to 90 minutes, two to four times weekly. These duration and frequency is dependent on goals and fitness level.
Why Zone 2 Helps With Active Recovery
Zone 2 is a great active recovery implement, especially for soreness. Zone 2 can help reduce soreness because the low-intensity movement increases circulation and oxygen delivery to recovering muscles without adding significant additional fatigue. Improved blood flow helps transport nutrients needed for recovery while assisting in the removal of metabolic byproducts and inflammation associated with hard training.
