Part two: The importance of gas analysis testing in endurance training.
Before I get stuck into this topic, I want you all to know that I do offer a fitness testing service, of the metabolic gas analysis kind, which straight away places me in a position of bias towards the exact title of this here blog! I want to put that out there first and foremost. However, I am 100% led by research findings and scientific evidence in my physiotherapy practice, and this blog is no different.
I really feel we should revisit a point made in last week’s blog before we dive into physiological limitations, respiratory capacity v’s capability and metabolic efficiencies! That is the simple act of enjoying your training. I touched on exploring the question of “why” you are training and also looking at your training as an opportunity to better your mental and physical health alongside performing well in your target events.
I listened to a friend’s podcast this morning (‘Flip the Script’ is really worth lending your ear to by the way) - Conor O’Keeffe talked about how easy it is for us to move out of the present tense when we are training on a bike or out for a run and start thinking about the future race that you have signed up to and whether you are on target in terms of your fitness and readiness for the race. He likened it to brewing a cup of coffee, “we’ve got to start enjoying the process of brewing in order to truly enjoy the sipping”. Same goes for Ironman or any event, long or short distance. The event is the coffee and the months of training, the brewing.
In the first blog, one piece of advice from a previous IM finisher was to “not underestimate the journey”. I’m guessing this is precisely what he/she meant. So, let’s remember this, especially when we work with metrics such as tidal volumes, breathing frequencies and VO2Max. I don’t intend to get knee-deep in exercise physiology here, but rather keep it readable and practical, so here goes.
Fitness test Vs Fitness assessment
A ‘Fitness Test’ will give you a fitness score/report but the data will also identify how you ended up with this score, and what physiological limitations prevented you from scoring better.
A ‘Fitness Assessment’, much like an FTP “test” on a bike or a bleep test, will give you a fitness score only.
Both have their merits and there are appropriate reasons to use both.
Fitness testing is important in endurance training programmes because it reveals the limitations that are hampering the athlete’s progress. Let’s discuss a typical VO2Max ramp test protocol using a gas analysis testing device. This test involves wearing a facemask that measures O2 intake and CO2 output, the client initially starts off on the bike/treadmill/rower at a very low intensity. The intensity is increased by a certain amount every minute until exhaustion. The information that can be gleaned from this type of test is fascinating and hugely important to know, especially for those who are not seeing improvements in their objectives and those who are lost in the sea of information and misinformation around training principles and metrics.
This may be a good time to tag in the very recent podcast video recording on Zoom between the head exercise physiologist and physio of PNOE gas analysis, Daniel Crumback, and myself. We discuss the use of these metabolic gas analysis tests with my own clients and also discuss ‘before and after’ data from my own personal tests.
My personal case study was discussed on the podcast because it really hits home the importance of testing for endurance training. I’ll talk about it here and if anyone wants to hear and see more, you can click on the link here. (If you want to bypass the intro and other bits and pieces, then skip to minute 17 to get to the juicy data discussion)
My training patterns changed after the birth of our daughter in August ’18. With less time available, I swapped out the long bike rides and replaced them with short harder sessions. My most frequent run was a hard five or six kms into the hills around our house. I raced sprint triathlons and middle-distance adventure racing. This type of training continued into 2020 (without the races of course). So my physiology was set up for short, fast, intense exercise and this is exactly what you see in the data from a VO2Max ramp treadmill test performed on the 11th of September 2020.
The main finding that I want to draw your attention to here are the two lines that cross over each other and then go their separate ways. The lighter blue coloured line is my carbohydrate usage as a fuel source during the test and the darker blue line along the bottom is fat usage. The Pink section of the test is the warm up and the speed was a very easy 5.1km/hr or 11:46minutes per km. You can already see carbohydrate usage begin to rise within the warm-up period of the test and with each ramp increment representing 1.3km/hr, you can see that by the time I reached 13.2km/hr or 4:33min per km, I was not using fat as a fuel source at all. This is what is called poor low-end metabolic efficiency. It is also something you do not want happening if you are working towards a long distance endurance event, such is the Ironman and 70.3. For these types of events, the goal is to be efficient at fat burning so that you can maintain moderate to high exercise intensity for longer periods. It’s not all about developing a fat burning engine, capillaries that carry oxygenated blood to the moving muscles will grow when the athlete trains in an accurate zone 2 heart rate range. It is safe to say that my capillary count was not impressive because I rarely trained in zone 2 in the couple of years before Roisín was born and not once after she joined us! Same can be said for mitochondrial density and function. Mitochondria also increase in content with zone 2 training. Mitochondria are the powerhouses of our cells where energy is made, so it goes without saying that the more mitochondria you have (density) and the better that mitochondria work (efficiency) the better you perform in endurance events. Research is showing that mitochondrial efficiency is mostly improved with high zone 5 interval work while their density is increased with high training volume in zone 2. It is a completely different story if your goal is to run 100meters, but that’s for another day’s discussion.
These are my accurate zones that were identified from the treadmill test on the 9th Sept:
Zone 2: Heart rate range : 102-112
Zone 3: HR range : 112-148
Zone 4: HR range : 148-160
Zone 5: HR range : 160-185
I then set my mind on carrying out the appropriate training in order to improve my low end metabolic efficiency. I picked a 9km run on flat terrain and for the purpose of the “injury prevention” blog that is coming next, I gradually introduced the volume of kilometers over a few weeks! In order for me to stay in zone 2, I was jogging at a average pace of 6:50min per km. These were morning runs (2-3 per week) of over 45mins and I preceded them with black coffee only and had breakfast afterwards. The details around nutrition will also be covered in a later blog. I was also including four to five intervals of zone 5 sprints for 30secs within the zone 2 session, as zone 5 intervals will also grow capillaries and improve mitochondrial function. This will improve both low end and high end metabolic efficiency, where high end means higher intensity exercise.
I worked away on this plan which also included one or two turbo-training sessions on the bike per week with the same approach. I didn’t know my zones for the bike and please note, we can not use our running zones for cycling and vice versa because they can be significantly different due to how mechanically efficient you could be on a bike compared to running. So I used the rate of perceived exertion chart to try and stay in zone 2 as best I could for these sessions. The RPE scale is a nice tool to use if you do not have any interest in monitoring heart rate, power, or fitness testing. By the end of the 9th week, I recorded a run around the same 9km route but this time the average pace was 6min per km and staying predominantly in zone 2.
Time for a re-test: 8 weeks is a good time to re-test especially for someone with potential to change their physiology as much as I did. If you would like to see a home-made/clinic-made movie of the retest, there it is below. Warning the quality is not cinema standard! I somehow managed to complete the test with Roisín running around the clinic causing havoc.
I retested myself on the 15th of Jan 2021 using the same protocol and here are the new training zones pulled from the data
Zone 2: 137-151
Zone 3: 151-158
Zone 4: 158-170
Zone 5: 170-189
And this is how the data looked on the graphs
Very easy to see the change in fat burning ability here with the darker line (fat usage) staying with the light-coloured line (carb usage) for longer into the ramp test before the final crossover point occurs at a heart rate of 150 beats per minute.
The training recommendation based on this significant positive change was to continue to work in zone 2 with zone 5 intervals for the rest of January and all of February. My new zone 2 range meant I could push the boat out some more. I recorded a recent run at a pace of 5:21min per km with average heart rate of 141 around the same 9km route. Happy days.
The next paragraph gets a little deeper, perhaps deeper than knee deep, into certain respiratory metrics. For those of you who are interested, keep going.
Hyperventilating (taking too many breaths per minute) at a low intensity running speed is quite commonly picked up with testing. This breathing pattern tends to result in lower-than-normal lung volumes (air intake). When monitoring these metrics in the data after the test, the tidal volumes or litres of air per breath do not increase appropriately as the running speed incrementally increases. This type of breathing pattern can lead to early fatigue of the diaphragm (our main breathing muscle), causing something called the metaboreflex to kick in which will slow the athlete down.
The metaboreflex is a survival mechanism, it causes a redirection of oxygenated blood to the diaphragm and a reduction of blood supply to the working muscles, which limits performance.
That is an example of a respiratory limitation to exercise performance and can only be detected using gas analysis testing. In this example, there is certain information we need to know in order to accurately diagnose the limitation. Is this a respiratory capacity, or a capability issue? To do this, the client’s lung capacity is measured using a spirometer before the fitness test. This is your standard spirometry assessment where you blow as hard as you can and as much as you can into the spirometer device. It measures your lung volume (how much air you can fit in your lungs) and your ability to push out air quickly. If these pre-fitness test measurements are within the predicted norms for your age, height, gender and ethnicity, but your actual fitness test values do not reach at least 75% of your predicted norm, then we can conclude that you have a lung capability issue. This essentially means that you have good lung volumes at your disposal but you are not using the volume sufficiently when exercising. On the contrary, if your spirometry scores are below their predicted normal, this is called a respiratory capacity issue and can be improved through specific respiratory training. An example of respiratory training would be to work on taking deeper breaths and improve your ability to push air out quickly from your lungs. Known diseases that affect lung capacity are taken into consideration.
With better awareness of the type of respiratory limitation comes better tailored advice around training.
I want to wrap up this week’s blog but before doing so, here are some interesting results from the same survey that was used in the first blog.
Are you aware of a portable gas analysis device called PNOE that can be used to calculate your VO2Max, resting metabolic rate, training zones, preferred fuel source and exercise limitations?
80% of the 91 respondents were not aware of such technology.
Would you be interested in getting a VO2Max test to identify your training zones and fitness limitations at an affordable cost? Example of limitation: At heart rate of 160-170, lung volumes significantly reduce showing a respiratory limitation at this training zone. You will be given specific advice to address these limitations following your test and a retest will be carried out in 8 weeks to reassess these limitations and set new training zones
You can read more on the fitness testing service and take a look at a sample report that is emailed to you following your test along with a zoom call from myself to discuss the data and make training recommendations. Hit the button at the bottom, and if interested in this sort of stuff and want to be kept in the loop, sign up to the newsletter below.
Many thanks for reading, for now we got to keep on keepin’ on.
Physiotherapist and Nutritionist
www.thebikefitphysio.com & www.lifefitphysio.ie
P.S. Conor’s blog is called “Flip the Script”. His take on life is refreshing in that he speaks from his own learnings while remaining incredibly humble. He has morphed into an ultra-distance runner over the last three years and has a few projects up his sleeve for when restrictions eventually lift. He’s the guy that ran around his patio for 24hours in aid of Pieta House!
P.P.S Blood flow restriction and altitude training both share a commonality in that they cause reduced oxygen availability (hypoxia) which results in greater capillary and mitochondrial growth. This is because hypoxia is one of the key determinants for capillary growth. It is also worth noting here that both capillary supply and mitochondrial density are really important for pushing up your lactate threshold (point at which lactate does not accumulate) and critical power (tolerable duration of severe-intensity exercise) through delivering more oxygen and removing substrates that cause fatigue. That goes out to those of you who are into hard training sessions, only. I for one experienced first hand the benefit of capillary growth and its positive influence on lactate threshold performance when I took on the first race in the Kayathlon virtual racing series yesterday morning, a 5km run, as fast as you can!! Managed to complete the 5k in 18:50mins, bettering a previous PB set a few years back at the Ballincollig park run of 19:55. As mentioned earlier and in the podcast, I had not been doing any threshold (intense) training in the past 12 weeks and more. Bloody couldn’t get over how comfortable I felt on the run. The science works!