I’m new to intervals and fitness in general. I am overweight and completely unfit 40 year old male.
I bought a smart trainer and am using Zwift to get in shape and lose some weight in combination with a more healthy diet.
I did a few sessions on Zwift and am now starting with a training plan based on my FTP. I did an FTP test in Zwift which resulted in something around 170w which shows how badly out of shape I am…
Anyway, my last workout session on Zwift was a tempo session which wanted me to do some intervals in Z3 (145w).
When I examine the details of that session in intervals, it shows that my heart rate was 95% in the recovery zone (0-135bpm). It’s true, my HR never really went high but it surely didn’t feel like a recovery heart rate. At most moment I wouldn’t be able to have a conversation.
Then, when I go into the activity power, 35% is in the VO2 max zone, 17% in Threshold and only 10% in tempo.
What I don’t understand is that for tempo, intervals.icu says 76-90% 98-117w which is weird because intervals.icu says my FTP is 170.
Can someone shed some lights on these metrics? Especially my heart rate… I don’t understand why it says it was a recovery HR while it sure doesn’t felt like it…
Also the descrepency between activity power and HR… How can my power be in VO2 Max while my HR is still in recovery…
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There’s a lot to this question that are others are probably more knowledgeable about, but I don’t see you mentioning heart rate during your FTP test.
With your FTP test you have established your power zone’s, which Zwift uses to create plans and sessions, but probably your heart rate zone’s aren’t established yet.
If you go into settings in Intervals you can set up your zone’s for both power and heart rate (and pace for some sports as well).
Although power and heart rate are definitely related and can be tested in the same test it’s impossible to derive one from the other.
You will need to check the settings in Zwift and Intervals to make sure they are the same.
There is all kind of things that make me suspicious in this story. Starting with
Seems like an FTP of 170W doesn’t fit with the above, unless you are really overweight. What would that FTP be in W/kg? If you are around 1.7 or higher, things don’t look to bad
. Some weight control and regular exercise will do wonders.
What you need from your FTP test is the 20m max Power and the avg HR that was measured during those 20m.
That will give you a good starting point, because FTP can be estimated at 95% of that Power and the HR plateau that you should have reached is close enough to LTHR at this stage.
Make sure to update those 2 values in Zwift and in Intervals. Watch out to select HR zones based on LTHR and not on HRmax!
And some solid advice for beginners: take it easy and start developing your aerobic base iso jumping to High intensity workouts. Give your body a chance to adapt to your new lifestyle without risking injury.
As above, which FTP test did you do on zwift?
Ramp test don’t give Threshold HR.
You need to do a 20min threshold test, then look at avg HR.
Some say use avg for the 20min some say use 95% of Avg HR to get
Threshold HR. be in the ball park
Also bare in mind Zift use slightly diff % of FTP for their zones.
Zwift Zones
0 - 60 % Gray
61-75% Blue
76-89% Green
90-104% Yellow
105-118% Orange
118% Red
Interval zones
% of FTP
<55
55-75
75-91
91-105
106-120
121
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Some good applicable advice here!
All in all, just stick with your plan.
The more (relatively) unfit you are, the larger the gains will be when you start. Which is stimulating you to keep working out.
Seems like an FTP of 170W doesn’t fit with the above, unless you are really overweight. What would that FTP be in W/kg? If you are around 1.7 or higher, things don’t look to bad
. Some weight control and regular exercise will do wonders.
It’s more in the line of 1.3-1.4 W/kg.
What you need from your FTP test is the 20m max Power and the avg HR that was measured during those 20m.
I did the shorter FTP test in Zwift. From Interval.icu it shows those 20min as 174 W with an average HR of 146 and max HR of 165.
174W for 20-min will be about 160-165W for estimated FTP. The average power for 20 minutes needs to be multiplied by 92-95% depending on your training history.
How did it feel? Not as hard, hard, really hard, maximal effort?
It felt the hardest thing I did on Zwift so far.
I had to pace myself as I could not sustain my power so had to drop once in a while. It felt like I could’nt go harder and was really happy those 20min were over 
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I’ve only been training with power and heart rate since 2017, but thinking back, trying to judge what I was really capable of doing for 20mins was very hard.
Six years on, I usually have a decent idea of my capabilities and often “negative split” efforts, starting slightly conservatively and gradually increasing effort if I think I can maintain that power until the end of the test or virtual time trial.
My suggestion would be to think about trying a ramp test in Zwift, perhaps even the lite version, if your turbo trainer is smart.
The standard ramp test starts at 100W and increases power by 20W every minute, while if I recall correctly, the lite version starts at 50W and increases by 10W every minute.
You simply select a middle sprocket and your bike’s small chainring, stay seated and let the turbo increase resistance until you can no longer maintain approximately 70rpm.
Zwift takes your best one minute of power and gives you an FTP estimate based on 75% of that figure.
The lite ramp test maxes out at 250W, but if you really do have an FTP of 170W, you will be at the point of giving up around the 230W minute.
Ramp tests can be a bit hit or miss for some riders (they often flattered me in the past), but they are useful for a ballpark when starting out with training by power.
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it shows that my heart rate was 95% in the recovery zone (0-135bpm). It’s true, my HR never really went high but it surely didn’t feel like a recovery heart rate. At most moment I wouldn’t be able to have a conversation.
As the others had said check what values you have recorded for your FTP and max HR in both zwift and intervals.
What is you max HR? If you recovery HR zone is up to 135 that is saying your max HR is around 220 which is very high and very rare.
Not 220 - your age, not some random spike, but the maximum value your have seen after a hard effort which has seen your HR climb and climb, until you can’t ride anymore and want to vomit (that type of hard effort).
For me the 5 zone HR are roughly the equivalent of the first 5 zones of 6 zone power model, if I have spent some time at that power zone (a couple of minutes or more).
Conversation is:
zone 1 normal
zone 2 normal, but a little measured, with a few pauses, other people will noticed a difference.
zone 3 measured, a lot shorter sentences, more pauses.
zone 4 a few words at time
zone 5 grunts
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I was coming here to say exactly the same thing. 220 minus your age is a load of crap. (Like BMI it was meant for population averages and not many people are the average person).
I’m 53. 220 - 53 = 167. That’s pretty much a zone 3 effort for me. Usually my racing average HR is in the 170s with low 190s on a maximum effort. I take 197 as my working max which I hit a few times a year.
Lactate threshold (MLSS/LT2/FTP) of 4mmoL is also a population average.
Looks like you’re at the far extreme of the population avg because a HRmax of 197 at age 53 is rather uncommon. Not saying it’s impossible, rather exceptional.
Unfortunately it doesn’t mean I’m an exceptional cyclist. 
But my point was that Max heart rate should be a measurement, not a guess.
Is your max HR something that can be trained and lost? So for example, since I’m out of shape, will my max HR be below average but once i train more, my max HR will also increase? Or is max HR just something personal that wont change with training?
Let’s put it this way. Within 4 months of starting regular cycling (pushing myself, that is) I saw a heart rate of 196.
That was 2018 (I was 77kg, now I cycle about 8000 miles/year and weigh 67kg)
Highest working max is 197 but I have seen “freak” readings above 200 a couple of times.
During normal “working very hard” e.g. climby sprints on Zwift I will still routinely see 190s but only 197ish a few times a year. Things like temperature also come into it. One of the times I saw >200 was a very hot day on an outdoor ride. I kind of discount those as outliers though and take 197 as my working max. So - no it hasn’t really changed after the first few months.
HRmax is not trainable. It’s mostly genetic. It will decline with age but it is well known that people who regularly exercise keep their HRmax more stable while aging.
Important remarque is that a non-trained individual will have troubles to get a true HRmax, because this type of effort is something that you have to learn to sustain. A beginner will most of the time give up long before reaching HRmax because the pain and feeling is something they have never experienced before. Unless you once were chased by an escaped lion perhaps… Then again, you probably weren’t wearing a HR chest strap at that moment 
It’s also not recommended to test HRmax for a non-trained person. You’re way better of setting your zones based on a LTHR estimate iso risking a heart problem. There is more then enough time to learn how to handle those extreme feelings once you get in better shape.
As a beginner, your AeT is much more valuable to know or estimate. It’s the point where your breathing starts to pick-up. Do lots of exercise with AeT as an upper limit to improve your cardiovascular health. It may seem like a ridiculously low intensity at first, but if you do it consistently, you will improve fast and safe. Mix it up with some sparse efforts at higher intensity (doesn’t have to be specific) after 4-6 weeks. And only start doing structured tempo and threshold intervals after about 12 weeks of regular training. The biggest advantage for ‘unfit’ individuals is that they improve fast. Performance will rapidly increase just by exercising consistently. Take advantage of that by making it visible with charts, it’s extremely good motivation!
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Getting fitter means being able to train for longer, close to your maxHR.
As @MedTechCD has said, it’s not trainable, but it does serve to measure levels of power against maxHR. MaxHR in fit people, doesn’t decay by one beat per year like the population average of 220-age.
I would say the description of “less fit people give up before hitting max” is a good description. A strong base is required, to be able to build on top of that.
All out efforts, to feed the power duration curve (and the pace curve for those not using power) is always a good thing to do. During a 5-6m all out effort, if paced well, should see your heart rate hit max, or within a beat of it.
Great that you want to improve your fitness!!! Welcome to the club.
Regardless of your heart rate and FTP, you need to start easy. The best rule is to use the Rate of Perceived Effort** — RPE. You should aim for an RPE of 2-3 (light activity: easy to breathe and carry a conversation). Start with 30 minutes 4-5 times a week for a month, then increase to 45 minutes and so on.
The core of endurance is a strong base phase that teaches your body to go long and use fat.
This will also give you time to learn about your body and the different tools like FTP, Heart Rate and Vo2 max… etc.
I hope this helps.
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I haven’t looked into any studies that might have been used in the answer. But in this podcast Best 60-Minute Workouts, Raising Max Heart Rate, and More - Ask a Cycling Coach 405 - YouTube they suggest max HR can be “trained”.