I’m a zone 2 disciple and have stuck to 80% of my volume in Z2 pretty religiously. But recently I was looking at a pro’s power zones, and his zone 2 went up to like 270W! That’s basically my FTP and I am using a lot of muscle to achieve that. So I understand and accept that this person’s cardiovascular system is that much more developed than mine, and that this power output doesn’t substantially stress them, but at the same time, they are also a skinny dude like me who is doing a lot of serious muscular work for 4-6 hours, whereas my zone 2 is work but it’s not that muscularly demanding. I’m just growing skeptical that a pro’s Zone 2 scales physiologically with a non-pro’s zone 2. Or do training zones scale well across fitness levels, both in terms of cardiovascular and muscular training stress?
Below threshold, they do. Above threshold, it’s quite a bit more individual.
While your physical size is the same, the professional athlete’s VO2max is likely markedly higher, and other genetic factors related to muscle fiber composition are likely very different. He is just able to utilize a lot more oxygen and create a lot more ATP aerobically than us mere mortals. While hard to believe, that athlete putting out 270W probably feels like you do putting out 170W.
It is not hard to believe that he feels like he is putting out 170W in terms of cardiovascular response, perceived effort etc. What I am skeptical of is the idea that his muscles are responding as if he were putting out 170W when he is riding 270 W. If he had substantially more muscle mass, maybe, but he doesn’t. He’s still doing the same work with (I think) similar muscles when I do FTP, but he’s just not getting as tired from it (and thus it’s his endurance zone). My point is that these zones are derived from physiological cardiovascular markers like blood lactate, not muscle fatigue. So aren’t the pros getting a better muscular workout from their zone 2 work, even scaled for cardiovascular fitness?
Those zones aren’t derived from physiological markers like lactate unless you’re specifically using a three-zone model derived off of LT1 and LT2, which are simply inflection points in a lactate generation curve. There aren’t raw lacate numbers that everyone is in in zone 1 or zone 3 or zone 6. The Coggan zones are derived from percentages of Functional Threshold Power, which is loosely related to LT2, but isn’t defined by having much to do with lacate per se… it gets squishy in there.
As to your question about a better muscular workout… not really. In general terms, the pro is doing more work than you are because they are able to hold a higher power. The kJ expenditure will be markedly higher, but that just means they’re utilizing more energy, need higher fuel intake and generate more ATP aerobically, as mentioned above.
Muscular work is all based on stimulus relative to your specific baseline. So for the athlete above, riding around at 270W isn’t providing a massive muscular stimulus just as you riding around at 170W isn’t either. Both are lower-end aerobic efforts, and that athlete is just conditioned to be able to do that level of work aerobically: they won’t feel more soreness or DOMS than you do from riding at a zone 2 intensity, and they’re not doing more physical damage to their muscles because they are already adapted to do that level of work.
It really does have more to do with energy production at the cellular level (aerobic oxidation) and that athlete’s ability to utilize more oxygen to produce more energy to perform more work from the muscles. But at the core, they’re just maintaining that ability to do that work aerobically, not specifically making those muscles capable of more force generation (i.e. stronger).
Thanks for your response. As a professional biologist, and someone who feels muscle limited, not cardio/breathing-limited when riding at threshold, I have to accept that this difference is at the cellular/mitochondrial level, not at the organ (hearts/lungs) level. I could probably hold a broken conversation with you at threshold, and when I was a competitive runner, I would always feel like it was my lungs not my legs that were the limiting factor. But with cycling, my legs are definitely the limiting factor. I know this because I can reliably improve my threshold power by increasing my cadence, which shifts some of the load from my legs to my cardio system.
Same here a few years ago (came from competitive running as you did). Ditto to @Kurt.braeckel response. I will add anecdotally that I overcame those muscular limiters by not strictly sticking to <LT1. I introduced low tempo (in my case, in the form of Steve Neal style tempo). I’m now a pretty decent “diesel” rider, whereas early on I was relying on natural talent from running (basically, I could climb, but got dropped when the pace turned up on rollers and flat roads). These days, I turn those screws on other riders (to a point, of course…LOL).
My endurance riding remained mid-Zone 2 (Coggan), but you can and should incorporate some low-tempo into your “80%”.
Regarding that 270W number. ISM has a well-know study on metabolic flexibility. You can see some actual LT1 and FatOx/CHO values from world tour riders in that paper. There is a bit of variability but one very important take home for me was that you simply cannot base LT1, etc. off of FTP. Example: it is not uncommon for a WT cyclist to have an FTP of ~400W. That same rider might have an LT1 around 270W. That’s .68 IF. If you talk to most self-coached amateurs, they are going to use .75 IF as an approximation for LT1 (right or wrong), unless they have measured it or they are coached.
Yes, I experienced this when I started riding competitively a long time ago from a running background into triathlon (and now road racing).
When I started doing triathlons, I was capable of running sub-5 min mile, 17 min 5Ks… I could also squat 2x my bodyweight… but my FTP on the bike was 230W. It had little to do with raw leg strength OR my cardiovascular fitness. Simply, from a neuromuscular perspective, I wasn’t able to put that kind of power down. Like a lot of people, I was quad-intensive with my pedal stroke and my body didn’t know how to recruit the right muscles and fire them appropriately to generate power for longer durations. I’ve always skewed a bit anaerobic - I have above average “snap” and a pretty good sprint for my size/age, but I’ve gotten a lot better aerobically the past season or two.
Like you, I still can ride at higher intensity at a higher cadence. My cardiovascular fitness still trumps my leg strength to this day, but that’s not tremendously uncommon. It’s difficult to translate leg strength into FTP. Squats and such will increase force/torque generation, but not the ability to sustain that for “about an hour”.
It really is at that mitochondrial level and learning to recruit the right muscle fibers (and more of them) to get maximal aerobic work capability and that takes a long time. Obviously, higher O2 utilization capacity on the bike helps and is largely genetic, but it is trainable. The peripheral gains you can get from LSD training take quite a bit of time; boosting stroke volume (and also just getting used to riding at maximal O2 uptake) is possible in a somewhat shorter period, but maximal gains take more time. Muscle fiber type matters as well, and that can shift… with time.
So it’s all about being patient and doing the right kind of training. Train your brain and body to ride at threshold; probably more importantly, get those peripheral adaptations by riding long and slow.
Thanks Kurt and Timothy for your thought provoking and encouraging replies. I’ll keep at it!
I just saw this article today from Inscyd. While not exactly z2, it was interesting:
In this video, Wout van Aert mentions that his FatMax intensity is about 350 watts
mentions in the video, when he trains at FatMax, he usually does it for about 20 minutes before switching back to endurance intensity. Which is probably more in the ballpark of 230 – 240w.
WHY FATMAX INTENSITY IS TOO HIGH
To maintain an exercise intensity for multiple hours, you need to have enough energy in your muscles. The image below is an example of an athlete with a FatMax (green line) intensity of 290w. At this intensity, he/she also burns more than 90 grams of carbohydrates
So even in Z2, a pro is likely going to burning a TON more calories and carbs if they’re on the upper end of their z2…
Personal note… My fatmax of 239w… I’m also burning 89g of carbs… Lol
Shows how much better developed the pros fat oxidation is compared to the rest of us.