10/26/2023
About two years ago I thought to myself that we need to find a better way to define training zones. Since then, I have assessed every model under the sun. There are 3 zone models that from a metabolic perspective probably make the most sense because there are then metabolic anchors that form the break points. Then there are even 5 and 7 zone models. Which are best, and which are most accurate, the answer probably is best stated as none of them. There is limitations to all of them.
Some set training zones based on max heart rate, while others use lactate measures, while referencing heart rate, while still others use gas analysis. The important point to understand regardless of the method is how the zones are used and implemented in training.
Take for example the recently published paper from the Aker Daelhie Team in Norway. They published a slightly different training zone model than I am used to seeing out of Norway. I believe in light of the popularity of Zone 2 Training it is important to parse out how the proponents of a system of training utilize the zones.
In this system there is significant overlap in Zone 1 and 2 in terms of lactate levels with Zone 1 being < 1.5 mm and Zone 2 being 1-2 mm, with the maximum heart rate ranges being what I consider a consistent range with how most training zones are delineated. The implication from this range of lactate is that it is highly variable and not the same between individuals. From the published paper we can see this Zone 2 does not fit with what some may consider Zone 2. It fits how I would describe an Endurance Training Zone not to exceed 70-75% of maximal heart rate. We need to realize that lactates may vary greatly on a daily basis, and can’t be viewed be as hard and fast anchor for a specific training zone.
So, if one wants to use and reference the proposed training zones system of Aker Daehlie one should also be aware of the following statement made regarding their definition of Zone 2 in the published document.
“Zone 2:
Semi-hard long sessions with a heart rate at around 140-155 bpm and with lactate up to 2 mmol/L, is considered intensity 2 training. Scholar’s debate over the importance of this training. In our experience, this training costs more than it is worth, and should therefore not be prioritized. I2 can work well to learn/automate correct technique. Again, evaluate cost vs benefit! Typical length of a session is 1 to 3 hours of continuous activity.”
The Zones 3-4-5 are close to how many would describe training in those ranges. However, in this case Zone 3 is a bit lower than how it is often described. But we also know the Aker Daehlie Team is primarily a long-distance team and we don’t know if they might use different training zone ranges for World Cup skiers or perhaps the World Cup Skiers may do more of their intensive training in Zone 4
The following is a chart is often used to illustrate how one of the best female cross-country skiers trained during her most successful years. This is from an extensive study are Marit Bjorgens training.
to 3 hours of continuous activity.
But to provide context the following are the training zones used for this athlete to define the Low Intensity (LIT), the Middle Intensity (MIT) and the High Intensity (HIT) Zones. The Low Intensity Zone is where we might expect to see it, 67-75% of maximal heart rate. However, there is a large gap, some 30 beats per minute between the Low and the Middle Intensity Zones. MIT zone being at 89-92% of maximal heart rate. So, the MIT zone would be quite different from what is described in the Aker Daehlie paper.
Another like the Zone table published by Aker Daehlie. Basically, a good theoretical model, but again I would suggest that training above 75% of maximal heart rate for endurance is unnecessary and the cost/benefit does not suggest a benefit. We also see the VT1 is probably for most athletes NOT at 80% of maximal heart rate.
Most of us consider the training zones as hard and fast, me included, but this is not the case. The following chart illustrates the possible range of metabolic and neuromuscular benefits of different training intensities. I believe the reason to use zones and monitor training is to ensure effective training adaptation. That is why I say training endurance at more than 70-75% of max heart rate does not have a positive cost/benefit. As recovery time will increase, adaptation slowed, and the time to readiness for the next hard session can be increased.
My advice
• When analyzing what others say or publish, look closely and question what their training zones are based on. You must be talking the same language to implement any changes.
• Pick a training zone that makes sense to you, if you are going to use lactate you have to do frequent spot checks, so you understand your individual daily variation.
• Use new and emerging technology, respiration, muscle oxygen only with validation of consistency and variability.
• Don’t jump from emerging trend to trend, there are lot of them out there, learn from what has worked, and assess emerging science with experience. Remaining current does not mean trend hoping to stay relevant on social media.
• Be clear on terminology. The same thing can mean very different things to different scientists and coaches.
• Use a couple of test that present meaningful data and inform training decisions collecting more data does not make for better programs.
• For most people, perhaps everyone, the percentage of maximal heart rate is as good as in method to determine training zones.
