As I use TrainerRoad for cycling training and listen to its podcast, I have become more curious about VO2 Max. What are my genetics, what is my ultimate potential?
In general, I like looking at data from TrainerRoad, Strava, Wattsboard, and Stravistix, even though I neither race nor plan to race, unless it’s to be part of a team as a domestique. At best, I want to hit the magical mark of 4 watts per kilogram (I’m currently between 3.5 and 4) and be a potentially good Category 3 racer.
Unfortunately, VO2 Max tests, which measure how much of incoming oxygen your body can process (think of it as oxygen efficiency), are quite expensive at $100+. Thus, when I had a chance to try Revvo‘s simulation of VO2 Max for free in San Francisco, I just thought, why not?
Revvo claims 97% accuracy (P value please!) of the real thing, and since most power meters are +-2%, that seems reasonably good.
I was pleasantly pleased with the results as my performance was better than expected. Then, suspicion crept in and I kept reading to think about whether I should believe in them.
The two things I’ll point out are my measured VO2 Max at 61 and FTP (threshold) at 259 watts. 61 is 1 percentile for my age group. Wow! How badass am I? Even if we give Revvo a 5% error (versus claimed 3%) buffer, I’d still be at, worst case, around 58, which is really good. Unless I go pay for an official test, I don’t have much more to dispute, but imagining I can be in the top 1% of anything physically seems unreal.
The FTP test result, is a bit different. Revvo claims that my FTP/kg ratio is already 4. However, since I actively train and use a power meter, I think my actual FTP is perhaps 235. I say perhaps because my indoor FTP with TrainerRoad is 225, and even that is tricky. I always fail my FTP tests and just use that setting for my workouts. 225 works well (kicks my butt) for me except for oddly enough, VO2 Max workouts, which I’ve been reducing by 3-5% of FTP to complete them properly.
There are a few things that suggest my real FTP could be higher than my TrainerRoad one.
1) Indoor trainer power for many people is lower than outdoors. That may sound like I’m making an excuse to feel better (which I would love to do), but I can easily do 250 watts outdoors for a few minutes compared to indoors. For example, take this workout from 9 months ago in which I climbed at 271 watts (4.3 w/kg) for 4.5 minutes. I assume (when I first started using TrainerRoad, I didn’t have a power meter, so I don’t have an apples to apples comparison from one year ago) I am stronger right now, but I don’t think can do that indoors. I’ve read different explanations for this. Some of this could be due to heat (air flow is not as good indoors even with fans), some of this could be due to the type of power you have to use on an indoor trainer versus outdoor roads.
2) My mental endurance is kind of weak. Going through longer TrainerRoad workouts, I really do get lazy and have to fight to avoid stops mid-way through 8, 10, 12, 20 minute bursts. Therefore, as Revvo suggests, perhaps I’m capable of doing much more.
3) I use a Powertap G3 power meter, which measures power at the wheel. Most power meters are pedal or crank based, which means they measure power at the source (your legs and feet). When power is measured at the wheel, this is the real-world power that’s driving the biycle. The difference is power that is lost through that transition from the frame to the drivechain. From different opinions I’ve read, this difference could be 5-10% or around 10 watts.
4) The positioning on my bike right now is quite aero. I’m probably slightly small for the frame (which is an aero-oriented bike already), and this likely means I’m stretched out even more horizontally than normal. How this impacts FTP is that it’s harder to breathe, which affects power. The Revvo bike, however, is more upright and with geometry more comparable to a normal or endurance focused road bike. Therefore, I could be losing significant power due to my position. I’ve been setting aside money to get a new properly fitted (perhaps 49CM) super duper (Specialized Tarmac? Roubaix? Canyon Ultimate SLX?) disc brake road bike, and have set 4W/kg as a performance requirement before looking at a new purchase seriously.
I mentioned some of this to Siva, Revvo’s CEO. He agreed that the power would more likely come out during an extended climbing session such as on Mt. Diabo (which I’ve never done). Revvo’s equipment is built on the Wahoo Kickr.
One thing I confirmed that I had long suspected is that my maximum heart rate is lower than the predicted rate for my age. My predicted max heart rate is 183 bpm. I always felt there could be something wrong with me because I would want to die cycling a little above 170. My friend David’s heart rate (he’s the same age) is mid-180’s. Revvo measured my max at 173. Cycling outdoors, I felt like I could sustain 165 reasonably well, but thinking that my true max was 180+ made me feel that I was just lazy.
I wanted to look more at VO2 Max as a meaure of performance and found this breakdown:
This chart suggests that I have a lower bound Cat 2 VO2 Max. If I adjust the FTP results for watts/kg, it suggests a 4w/kg power to weight ratio and about 250 watts.
So if we consider my indoor training FTP, wheel-based vs pedal based power measurement differences, and sitting position, is it possible I’m much closer to 250 and 4w/kg than I think? It’s possible. We’ll know more once I start to do more outdoor runs on my own (Strava KOM time!), but I prefer to keep training for the next couple of months to make sure that I’m at that level.