The Secret to Maximizing Zone 2 Training Results
It is an adage in sports performance that most people’s easy days are too hard and their hard days are too easy. What if I told you that your cardio workouts are too hard and that if you took it a little easier you would make much bigger gains and would actually burn fat while doing it? The science behind these facts is very well established.
Benefits of Zone 2 Training
Improved Metabolic Efficiency: This training zone optimizes the body’s fat burning metabolism, which is beneficial for long-term energy sustainability and weight management.
Enhanced Aerobic Capacity: Regular Zone 2 training increases your cardiac output and oxygen consumption, which are pivotal for endurance and increased VO2 max.
Mitochondrial Development: Zone 2 workouts stimulate the production of new mitochondria, enhancing the muscles' energy-producing capabilities.
Identifying Your Zone 2
To train effectively in Zone 2, it’s crucial to know your heart rate (HR) range. Subtract your age from 220 to estimate your max heart rate, then calculate 60-70% of this number to find your Zone 2. Some experts and training methodologies extend the upper limit to 75% for fitter individuals. The most accurate way to know your heart rate zones is to get metabolic testing through an organization such as the CU Sports Medicine and Performance Center. But that testing requires some time, effort, and money. Two other free and quick “tests” can help you identify zone 2:
You should be able to speak full sentences comfortably without gasping for breath.
If you can breathe comfortably through your nose during the activity, it’s a good sign you’re in Zone 2.
Using a Continuous Glucose Monitoring for Zone 2
Exercising with a continuous glucose monitor, such as the Freestyle Libre 3, can allow athletes to precisely identify when they are leaving zone 2 and entering zone 3. The science behind this is amazing, yet straightforward. During zone 2 exercise, muscles use both glucose and fats as energy sources. At the beginning of the session, glucose levels may decrease due to increased energy use by muscles. However, the body generally is able to maintain a relatively stable glucose level while in zone 2 by using fat for fuel and also releasing more glycogen into the bloodstream as it is needed. As exercise intensity increases (moving from Zone 2 to Zone 3), the body begins to rely more and more heavily on glucose rather than fats as fuel. In many cases, this causes a rise in glucose levels as the stress of exertion causes the body to release stress hormones, such as cortisol and adrenaline. Patients watching a glucose monitor during exercise can often identify a precise heart rate at which their blood glucose starts to rise during exercise, particularly if exercising in a fasted state. That is the exact point when they are decreasing the percentage of fuel that is coming from their fat stores, which indicates the HR at which they are leaving zone 2 and entering zone 3.
Metabolic Testing and Fat Burning
This is the most accurate method to find your VO2 max, resting metabolic rate, and your training zones. It is also the best way to measure fat oxidation rates (fat burning for fuel) during exercise. This testing involves analyzing the respiratory exchange ratio (RER), which is the ratio of carbon dioxide produced to oxygen consumed. Metabolic testing requires specialized equipment that measures gas exchange through breath analysis.
Optimal Time Allocation in Zone 2
For athletes and individuals looking to improve their fitness, I recommend dedicating about 70-80% of your cardiovascular training to Zone 2 and trying to strictly stay in zone 2 for that whole period. This is why bike trainers and treadmills are so useful for zone 2 training. If you drop out of zone 2, or allow your HR to climb into zone 3, you are losing a lot of zone 2 benefits from that point on in the workout. If you are training in zone 2 and push it into zone 3 for a period of time (such as outside on a bike and encountering a hill climb), it likely takes your cellular metabolism about 30 minutes back at a steady zone 2 HR for your cells to get back into a true zone 2, fat burning state.
Conclusion
Zone 2 training can truly elevate performance, but it is not just for elite athletes; it's a foundational element for anyone interested in improving their cardiovascular health and metabolic efficiency. By focusing the majority of your training in this critical zone and monitoring your heart rate to ensure you’re staying in the target range, you can achieve remarkable health and performance gains.
