Known 2

Known Two Training

Zone 2 training (exercising at a conversational pace) is having a moment in the social media world, and that's not a bad thing. The more interest athletes have in exercise physiology the better, especially when the theme is generally the benefits of slowing down. That said, there are a few aspects of this discourse to which I'd like to contribute. 

To open let's talk about the origin story for this type of training. Paavo Nurmi was a Finnish endurance runner who set 22 world records and won nine Olympic gold medals. He used an approach that featured a vast majority of training done at low intensities, including many hours of walking, and a much smaller percentage of hard efforts. Nurmi's domination of distance running spanned almost the whole decade of the 1920's.

Though it has been used by endurance athletes for over a hundred years, I'm seeing podcasts suggest modern influencers invented the approach. Nuurmi knew about it and 30 years later Arthur Lydiard formalized it in his practice and writing. Building endurance with a high percentage of work at easy intensities is long established. I hope podcasters continue to talk and post about it but please don't pretend you invented it. 

Who Are We Talking About Here?

When it comes to podcasts, articles, and expert guidance on the topic of endurance sport, one of the most important questions your critically thinking mind can ask is "Who are we talking about here?". The vast majority of such material never mentions the age or ability level of the athlete their guidance is relevant to. As you can imagine, the training methods for a 30 year old are not the same as for a 60 year old. If you are a recreational masters athlete, let's say over 50 in this case, the chances are pretty good the expert is not talking about you. That said, you have to figure that out for yourself. Some of the info may well apply but it is a matter of degrees. One of the most glaring examples of this is pre-set training plans. Rarely does a training plan state the age range it is aimed at. I strongly urge great care here. Who was this training plan written for? The answer to that question is never "Any athlete, male or female, between the ages of 18 and 80."

Pay attention also to studies quoted by presenters. Often exercise physiology studies are done on highly trained young athletes but somehow the conclusions of the study are being applied to everyone. If someone trains 24 hours a week for years, their physiology is not the same as one that exercises casually two or three hours a week. Furthermore, the promised benefits may only come from a high volume of training and we don't all have that kind of time to realise such benefits. Beyond simple volume we can look at capacity as well. To say, for example, endurance athletes should lift heavy weights, is to ignore the skill, balance, and foundational strength deficits of some less experienced or older athletes. Yes, some endurance athletes should lift heavy weights. Others should simply lift weights because they likely aren't at all and any introduction of resistance training will benefit them.

How Much Zone Two?

When an expert talks about how much zone two training an athlete should do I rarely hear them give caveats regarding the profile of this individual. Maybe these experts need to have a simple, declarative rule for all in order to deliver the authoritative presentation that builds their reputation. Again, who are we talking about here when we talk about zone 2 benefits? Is it a triathlete? A decathlete? Or maybe it's someone who goes to the gym a couple times a week? I can tell you decathletes don't do a lot of zone 2 training. Furthermore, someone that has been going to the gym for a while and has a decent fitness base will also get greater general benefits from a ratio closer to 50/50 than 80/20 if working out just a few times a week. As we'll discuss below, a heavy percentage of zone 2 is the best strategy for endurance athletes but it's not the best strategy for every individual out there. 

High intensity training (zones 4 and 5) is highly effective for the right people and in the right dose. Firstly, know that before doing high intensity you need to have a moderate base of cardio-respiratory and muscular-skeletal fitness. But when you are ready, higher efforts will deliver great results in a short time. You'll get greater increases in cardiac output (VO2Max) and specific strength and power, and still get gains in the energy burning metabolism as well. There is one big catch, though: the high level of adaptation is in response to the high level of stress and that means more recovery is required. You simply can't do high intensity exercise day after day or you'll over-train your system. For a non-endurance athlete that loves to exercise, they can add in extra workouts to their week as long as they are an easy intensity. For endurance athletes, finding this balance of easy and hard is a never-ending challenge.

Besides balancing our energy there are very important adaptations that zone two training delivers and they are critical to endurance athletes. The more time you spend in zone two the more efficient the body becomes at delivering oxygen to the muscles (due to an increase in capillaries) and the more efficient the mitochondria become at using that oxygen to burn fat for energy (due to an increase in the enzymes). Endurance athletes will burn both fat and carbohydrate while training and racing. The better they are at metabolizing each energy source, the longer their performance level will be maintained. Unless you are at a very low intensity, you can't race long distances only fueled by fat. Fat is still a critical energy source, though, as it lowers the amount of carbohydrate you need to consume while active. Metabolic flexibility, the ability of the body to switch from one fuel source to another, is very important to develop and a training approach that combines easy and hard training in a ratio of around 80:20 has been shown through history to be the most effective method for endurance athletes.

Summary

A focus on zone 2 training has been the principle method used by endurance athletes for over a century because it helps develop our body's ability to metabolise fat along with many other endurance related health markers. The easier intensity also means the athlete can amass a higher volume of training which leads to greater endurance fitness gains. Endurance athletes should also include some high intensity exercise as it boosts fitness in ways complimentary to zone 2 but, keep in mind, that high intensity also requires more recovery time so be careful with how much you do. 

Here's a little more on the physiology of zone 2