Spoiler alert: it isn’t that simple. While training within this zone is a vital principle within successful runners training schedules, it isn’t the only training zone you need to focus on for increased performance!
So, what is Zone 2 training? Why is it so hyped and what is the importance of running largely in this lower physiological training intensity for athlete development and fitness gains?
Within “Zone” training, most coaches and their runners utilise the standard five-zone model of training intensity outlined below:
Active recovery, low effort intensity.
Moderate effort intensity (a pace you can still hold a conversation out), low-ish perceived effort, controlled ventilation (heart rate) and low blood lactate levels.
Between your aerobic threshold and anaerobic threshold, often described as “tempo” or “grey zone,” carbohydrate utilisation increases and both heart rate and lactate rates are increased.
Around your lactate threshold, focus on carbohydrate combustion, higher lactate levels and balances both the aerobic and anaerobic energy systems.
High blood lactate accumulation, high level of maximum heart rate achieved, relies on anaerobic energy and fast twitch muscle fibres. Training in this zone is very hard to sustain.
Firstly, we know that working at a moderate intensity in Zone 2 we are below the “lactate threshold” and therefore the physiological stress being generated is far less then working in zones which high lactate levels are accumulated, resulting in reduced recovery times needed between sessions and less fatigue.
Therefore, ensuring a significant amount of our running time is at ‘Zone 2’ and below the lactate threshold, enables the ability to accumulate larger overall training volume without significant recovery periods, injury or illness.
Further to this, Zone 2 training is associated with many beneficial physiological training outcomes, such as increased mitochondria density and enhanced fat metabolism (think a bigger engine), and now that we know we can spend larger amounts of times training in Zone 2 (think baking the base of a cake), it demonstrates why large fitness gains can be made!
Now that it is understood accumulating a significant amount of your weekly mileage – perhaps 70-80% – in “Zone 2” is beneficial for all runners, it’s important to understand that training at higher intensities above the lactate threshold (Zones 3-5) is just as important for peak performance and can be thought of as the ‘icing on the cake’.
Training in the upper zones (3-5) is considered high intensity training which is extremely effective in inducing large amount of physiological stress on the body which forces adaptations – some of which are different from the positive training effects that occur within Zone 2 training.
For example, training at higher intensity is associated to enhanced mitochondrial respiratory function. So, whilst training volume seems important for building mitochondrial density, the higher intensity training which is utilised approx. 20% of your weekly training may be important for tuning them up to work most efficiently.
Running in Zone 2 induces less physiological stress which helps facilitate the accumulation of a larger overall running volume.
Running volume has been found to be associated with positive adaptations to mitochondria, which is some of the key purposes for effective endurance training and development.
Higher-intensity running influences other key training adaptations and should be carefully included within our running programs as they come at a larger physiological stress.
If you have been targeted by running content on social media, you have most likely seen the hype around the secret sauce of endurance training – Zone 2 training, with many influencers describing this as the magical training method to take your performance to the next level.
We all know that committing to a half or full marathon can be daunting, but often the biggest barrier our athletes face is understanding HOW to train for the big day.
