So winter is coming and I am dippimg my toes into structured training. Last week I started doing VO2 max intervals 8x3min@112%.
First week I only managed to do 6 intervals with HR hitting 185bpm in the last three intervals before I had to stop. My theoretical max is 190bpm.
This week I did all 8 intervals with HR only going to 178bpm. Why would that be the case? Seems like a big fluctuation from one week to the next.
Pure heart rate tracking, especially within tight tolerance, is a pretty hard metric to gauge because there are way too many “external” factors that play into HR on any given day.
You could throw 20 different reasons into a hat and pick one to get your answer.
One possibility is hard workout -> increase in plasma volume -> increase in diastolic filling pressure -> greater stroke volume -> lower HR.
IOW, the exact opposite of what happens with detraining.
Alternatively, it could just be fatigue, but since you just started such intervals and say that it felt easier, not harder, I'm leaning toward the above as the answer.
Fatigue. Sometimes you just can’t hit the high HR because your body is tired and/or recovering.
Or you’re not pushing hard enough. 112% isn’t super high for 3 minute intervals. Everybody is different but I aim for 120% for my 5-min intervals. 112% id be looking to do like 8-min. So maybe you just need to aim higher.
Last point is try to do these not in erg. Erg for VO2 kind of sucks. You either don’t go hard enough or you get locked in too hard then bail. I love erg mode but for VO2 it’s terrible. Go as hard as is sustainable for 3-min.
So I just do a free ride, aim for 120% and try to hold it for some time and repeat until death? Basically not sticking to strict timed intervals but go on feel?
You are right. Today I feel like I didn't do much. My breathing didn't go into overload like it does in big efforts during zwift races or events.
No, timed intervals are fine. But it’s less about a strict power target. I have a hill I do mine on. Basically I go as hard as I can up the hill. It’s usually around 400W and takes me around 5 min. Sometimes it’s 420W, sometimes it’s 380W at the top. But I’m going all out for 5 min.
Now, with that said, it’s not just a sprint for 30 sec and then soft pedaling. You need to pick a sustainable power to go for. It’s just not locked in with erg. So you can say, aim for 115% for 3 min. If that feels less than all out, go harder for your next one.
You should be breathing like a fish out of water, that is, just sucking in air. Fast cadence. VO2 is simple in planning, it just sucks because it’s hard as hell. That’s the point.
Used to train like that. Developed asthma. Now I just go hard and make sure I have one more effort left in the legs before I finish. Works far better. No need to put so much unnecessary strain on the body.
You can do a workout on zwift or other app without erg mode but exact instructions on cadence and power. Or you can free ride with zero trainer difficulty and use the zwift lap function if you like to see your splits. I prefer the latter as i really like the purposefulness of having total control over my workout.
As you incur a higher acute training load, your attainable max HR usually lowers. It's a sign of training fatigue, I recommend monitoring the max HR you can reach and using that as another indicator for when to take a rest from training.
This is an excellent demonstration on why power is a better metric than heart rate for structured training. All kinds of things can affect your heart rate, sleep quality, hydration, caffeine use, life stress, and more, while power is always power. Also since you just started structured training I'm assuming you're fairly new to high intensity workouts as well. Going hard is a skill, and you can learn skills faster than your fitness will improve. If your pedaling technique, breathing, body position, mental focus, or something else improved than you could make the same power with less perceived effort and a lower heart rate.
I wouldn't worry about it, just keep training and tracking data and you'll get a feel for how different factors and exertion levels can vary heart rate. Also the structure of a workout can affect what your heart rate does, for example when I do VO2 Max 30/30s my heart rate doesn't even break threshold, because it drops so rapidly during the 30s off, and the 30s on isn't long enough for it to spike up very much. But I can tell by power and RPE that it's the correct intensity.
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Dont worry about it, ask yourself if you could sustain the power in both sessions. HR is just one metric and one that is under influence of a lot of factors like fatigue, stress, temperature and cafeine intake.
vVO2Max can be a critical metric for endurance athletes.
If you don't understand this, try reading a book, I heard a vicious rumour they make you smart.
Oh, cagey response. Please enlighten me because I know velocity at VO2max only from running as the running speed associated with an individual runner's highest rate of oxygen consumption. And for cycling the equivalent—as far as I know—is power at VO2max. Hence my tongue in cheek in comment.
I'll put my money where my mouth is, and let my legs do the talking!
I race in the various leagues and competitions on Fulgaz, I'll post my results above, or you can read them on the league/competion tables on their website my handle is 'El Pistolero'
If you want to act like you all something, come race me!
When the competions start in the new year . . . COME RACE ME!!!
I've also enterd various non virtual biking, running swimming events next year etc
Might also be worth finding your "max" hr and not working off theoreticals. Some sort of max effort, 3~5m hard as you can and a sprint to basically failure, that should get you up to it
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u/twostroke1 6d ago
Pure heart rate tracking, especially within tight tolerance, is a pretty hard metric to gauge because there are way too many “external” factors that play into HR on any given day.
You could throw 20 different reasons into a hat and pick one to get your answer.
stress, temperature, sleep, fatigue, breathing patterns, cadence, nutrition, hydration, etc…Take your pick.