It happened again this morning, the scientists behind the scenes at Garmin confirmed (once again I might add!) that I am indeed “superior”! But friends and regular followers will of course already know that 😉
In seriousness though, what can we learn from VO2 Max on our fitness watch? In fact what is it anyway and does it make a jot of difference to us…
“VO2 Max” represents the maximum amount of oxygen that can be utilised by a working muscles to support the production of “energy” aerobically. As such it gives an insight to aerobic fitness. For Endurance athletes (such as runners & cyclists) you will already appreciate that your aerobic fitness will be one of the most significant influencers to your performance. Therefore, this number (which is expressed in millilitres of oxygen per minute per kilogram of bodyweight at “maximum” (aerobic) performance should be very important. If it goes up you are getting more aerobically fit. It may however be more valuable as a comparative measure against your previous readings rather than as a comparison against others. Being “superior” may well be meaningless!
The big caveat of course is that the number suggested by our sports watch is only a very approximate estimate. To calculate VO2 Max correctly you would need to visit a sports lab. Whilst our heart rate is also an approximation, as measured by sports watch (chest strap being infinitely better than wrist), when it comes to VO2 Max I suggest we really are drifting in to the land of very vague assumptions. To the point possible, where other than for motivation, it is probably next to useless as a training metric. Mostly because it is not actually measuring the amount of oxygen being consumed but rather inferring this based on Heart Rate.
Sports watches aside, it is worth looking a little deeper into what VO2 Max is all about. If you have read some of my other posts on this site, you will be familiar with Energy Systems and how they broadly work. You will understand that once our working muscles demand more energy than can be supplied aerobically, we begin to rely on our Anaerobic energy system. This comes with the downside of producing Lactic Acid and rapidly (seconds or a couple of minutes) our body can’t remove this from our blood. As a defence mechanism (to stop us seriously damaging our organs) our nervous system forces us to slow down. In very simplistic terms, once we cross that “threshold” then The End is close! This we term our Lactate Threshold and much of our training as Endurance Athletes is about increasing where that threshold occurs in our performance curve… In other words enabling us to produce more energy aerobically, clear surplus Lactic from our blood quicker and tolerate higher concentrations of it before we have to slow down.
You will probably be ahead of me here in concluding that (to all intents and material purposes) LTHR and VO2 Max are different sides of the same coin. This is partially, and sufficiently, correct for now. However with the former (LTHR) we are using Heart Rate directly rather than using it as input into a further calculation. Therefore I would suggest that as a training marker it is more useful.
Putting aside the accuracy of the number, can we take action to improve our VO2 Max? Well of course, and as a way of ‘visualising’ aerobic fitness, VO2 Max is actually very helpful. The simple question then, what factors are going to influence the maximum amount of oxygen a muscle can use?
Firstly if the oxygen is not physically available (present at the muscle) it certainly can’t be used. Therefore it is reasonable to assume that we want the greatest volume of “oxygen rich” blood turning up at the working muscle every second, minute or whatever other time unit pleases you. To achieve this we want to increase cardiac stroke volume (the amount of blood the heart shifts per beat in blunt terms!) and we increase this by training the heart muscle to squeeze more powerfully, and the way we do that is through long spells of low intensity work (you will have seen “Z2”, “Easy Running”, “Long Slow Run” and so on…). I will bore you with more details on how that works another time… But for today we are thinking about VO2 Max.
Secondly we need to ensure that we are carrying as much oxygen as possible in our oxygenated blood. Haemoglobin in our blood is responsible for doing this, so firstly making sure that our diet is facilitating the creation of Haemoglobin is a super easy place to start. We can then get more sophisticated (and expensive!) using altitude training… But other than at an Elite level, or if competing at a mountainous event when you live somewhere flat, altitude training is probably largely irrelevant. But it is a consideration for races such as Triathlon Alpe Du’Heuz and others.
Once we are on top of getting as much Oxygen to the muscle per minute, we then need to make sure it is getting used. (Remember – VO2 Max is the max volume CONSUMED not just delivered). For this we need to focus on muscle adaption to be able to efficiently receive the oxygen and use it to facilitate aerobic respiration (the production of energy in the muscle in the presence of oxygen). How? Simple, you stimulate your muscles to need to operate around the “threshold” of where they just haven’t quite got enough oxygen and tip into anaerobic respiration. You know about this (albeit you may have been unclear as to why you were doing it), but these are Lactate Threshold sessions; “long Z4 Cruise Intervals”, “Hill repeats” (in part!), “Tempo Runs”, “Progression Runs”, “Pyramids” (to an extent)… the list goes on. But does NOT include “sprint intervals”, “Minute on / minute off”, Maximal Repeats” or anything else that is very short bursts of something super intense. These later sessions do something quite different for you!
Final point for you to consider; your muscles can’t (meaningfully) adapt to using more oxygen unless the oxygen is physically there. Obvious right? Therefore this is why in the early stages of building fitness (Base Building as it is sometimes called), and with people that are lacking in fitness (perhaps returning after injury), most of my coaching focuses HUGELY (but not exclusively) on low intensity and controlled low heart rate work… Then as we progress and start to get into developing muscle output (be that faster and / or further), the emphasis changes to more upper aerobic and threshold (Z4) sessions. Makes sense right? But this cane be a very hard training regime for people to adopt. Low intensity Z2 Base work (call it what you will), feels easy. You don’t get to the end of 45minutes feeling like you have turned yourself side out! It doesn’t give you amazing data on your Strava feed and you have to do A LOT of it to get the real benefit. It doesn’t play well with the classic competitive person that wants the buzz and feelings associated with a “monster hard” session.. To compound this further, investing time into Z4 lactate threshold work before maximising your base fitness does not deliver great results!
The very activities that make you feel like you are working hard and “killing it” or striving for self harm because “no pain no gain” are actually not making you a better athlete at all. Not unless you have already developed (and tested to prove ) you have a maximal aerobic base.
Where does all of this get us dear reader? Is being “superior” according to my watch helpful? Of course who wouldn’t want to be called “excellent” or “superior”!!! It is motivational and strokes my ego nicely. But remember that is only a vague estimate if it was calculated from your wrist based (again estimated) heart rate – almost certainly as a specific number it will be wrong. So don’t fall into the trap of believing your own PR hype 😉
On the other hand, you can now look at the colourful representation on your watch face in a different way. You will understand what it *actually* means and why it is important. But above all else you will now have a better idea about how to improve your aerobic fitness in a methodical and rational way.n
