Posted: 2 weeks ago
Replies: 2 Admin
A fellow club member recently shared this video from Dr Iñigo San-Millán who is a doctor of endocrinology and metabolism as well as the coach of Tour de France winner and phenom Tadej Pogachar. In it he makes the case for the importance of Zone 2 base training, which I think has fallen out of favour somewhat in the last decade or so.
Like many other time crunched cyclists with other obligations, I have limited time to ride every week so I've been following the Sweet Spot training plans as recommended by TrainerRoad and many coaches (does TrainingPeaks favour Sweet Spot training as well? I haven't used it), with Base plans that progressively increase time spent just below 1 hour FTP. The theory being your fat-burning capacity is increased at the same time.
This seems to directly challenge that approach and argues that actually that time is better spent at maximum fat oxidization - the upper end of Zone 2, defined here as under 2.0 mmol/L - in order to improve the mitochondrial efficiency in your slow twitch muscle fibres. Not only does this increase your body's ability to break down, transport, and absorb fat in your slow twitch muscle fibres, it also improves the ability for those mitochondria to absorb lactate produced by glucose use (which there is always some, even in zone 2).
How to find your Zone 2 without access to blood lactate testing? The "conversation test" seems to be quite accurate, for me it seems to be a little below the transition from nose to mouth breathing but that will vary considerably from person to person. I would be very interested to get a metabolic lactate test done as a baseline as I'm currently in a barely above untrained state.
For me, I can feel when my power is slightly too high and getting into Zone 3 and my heart rate starts rising. This is what Dr San-Millán calls power to HR "decoupling" and is discussed more in the second video. This is also important for figuring out your duration, which is going to depend on your level of fitness. An untrained cyclist might need to start with 30 minutes where a pro is doing 3-4 hour or more Zone 2 rides. Ideally I think if you want to see improvements, you would want to do a zone 2 session long enough that you just start to see your heart rate decoupling (rising) compared to your steady state power output. Like anything else, you want to just nudge out of that comfort zone to trigger adaptations.
I've done a few of these sessions now and one immediately obvious benefit is you don't feel smashed after the workout and feel quite fresh the next day as well, which I think will make it easier to increase volume. I seem to be sleeping better too.
In previous years, I have often smashed myself on rides to "get the most out of it" with the result being I can't or don't want to ride for one or more days afterwards. This is counter-productive. In the videos Dr San-Millán points out that this kind of training will result in rapid increases in fitness - 50% gain in 6-8 weeks is not uncommon - but that your fitness will plateau without the increased mitochondrial efficiency that Zone 2 training provides. This has certainly been my experience struggling to get my FTP over 2.8 W/kg in previous years.
This isn't to say that high intensity training isn't important as well. The doctor says "you don't win races in Zone 2 or Zone 3" and that's true, and highlights the importance of identifying what you are training for. He recommends at least 3 or 4 Zone 2 rides per week (duration determined above), with some intensity intervals at the end of 1-2 of the sessions, then a long group ride or race on the weekend where you can do what you want or go all-out.
I want to do some casual club races, group rides, and a few granfondos this year, and I'm seriously rethinking the amount and structure of Zone 4 training I'm going to do. I'll post updates in this topic with the results as the year progresses.
Another interesting bit of data from a longer interview and deep dive into bioenergetics with Dr Iñigo San-Millán and Dr Peter Attia.
The top graph shows a ramp test (starting at 100W and increasing 35W every 10 min) and the blood lactate level measured in a professional athlete (PA), moderately active healthy individual (MA) and individuals with metabolic syndrome disease (MtS).
You can see individuals with MtS are already near the top of Zone 2 (less than 2.0 mmol/L) in warm-up, and any sort of effort pushes them out of Zone 2.
The really interesting part is the MA vs PA graphs.
You can see the lactate levels in professional athletes is super low all the way up to around 300 W. How is this possible? Are they really just burning fat?
No! The reason their blood lactate level is low at such high power output is because that lactate is being used as fuel by the mitochondria in their slow twitch muscle fibres. This is one of the great benefits of Zone 2 training, lactate is an excellent fuel source if the mitochondria are developed, and one of the reasons professionals can ride so hard for so long.
The second graph shows fat oxidization, which is the much slower process of fat being broken down, transported, and used by slow twitch muscle mitochondria. Zone 2 can also be defined as the range of peak fat oxidization. Blood lactate levels rise when your mitochondria cannot absorb and use any more lactate so it gets dumped in the blood - and that signals your body to stop breaking down and transporting those fatty acids. The more your mitochondria can use that lactate, the longer you can continue to activate the fat oxidization mechanism - it's win-win.
Note: I'm not a doctor and have no training in metabolism or biology, I just find this stuff fascinating.
The paper is available here if you really want to nerd out:
This is an interesting video that questions TrainerRoad and other's emphasis on Sweet Spot training and the very real burnout that many people experience when trying to follow a high volume tempo/threshold plan:
The comments are quite interesting, and I discovered TrainerRoad does offer a new beta polarized training plan
I'm probably going to try the mid volume (7h/week) polarized plan after the Tour de Zwift is over and see how that goes. From the TR description:
The Polarized Base blocks are designed to establish your aerobic base fitness with an emphasis on shifting training intensity to the ends of the spectrum and feature all-new polarized, high-intensity workouts. Following the traditionally referenced three-zone model for Polarized Training, these plans reside within a polarized training intensity distribution between 80/20 and 95/5.
If you want to increase your training volume, you can add an extra low-intensity workout. Doing so will further increase the plan’s polarization. After you complete the Base Phase, you can progress onto Polarized Build. These are experimental plans, meaning that this is the first version of these plans. These plans are still in their beta phase of production and will be improved upon as more data is collected.
I'll probably take that suggestion to "add an extra low-intensity workout" and add another 1 hour Zone 2 session per week as time permits, and reduce or replace the 2 hour Sunday ride with something shorter as I really don't like spending that much time on the stationary per session.