By how much should I reduce the target power for indoors workouts?


That’s something most of you already know: training can be much harder indoors than outdoors, at least for some people :stuck_out_tongue:

Well, that’s my case.

Here are two workouts I did this week:

  • on Monday, I did a LSD-120 outdoors. 2 hours, at an average power of 219W and an average HR of 139bpm
  • on Thursday, I did a LSD-90 indoors. 1h30, at an average power of 213W and an average HR of 150bpm (!).

I can feel it: it’s way harder on the HT ! I’ve been using the same PM on both rides. I know that I won’t be able to do some workouts indoors if I continue with the power target that Xert suggests for my outdoors workouts.

Is there a way to make Xert adapt the target power for workouts depending on if they are done indoors or outdoors ? And so that it doesn’t demoralize me when I train indoors (as I will for the next 5-6 months) ? I’d like to have different fitness signatures for indoors/outdoors, with a way to estimate one from the other… If I know my curve for my indoors workouts, I’d like to be able to estimate to what it would look like for my outdoors rides… and vice versa.

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Guess most accurate would be to do a breakthrough indoors - seed the signature say 10 to 15% lower (on all parameters) or whatever is required to make it a small BT, then extract to run the algorithm and save, in advanced MPA - and use that signature as the starting point for the next 6 months? And if you ride outside, manually change the signature for that ride (up 10% or whatever you figure out from your indoor BT vs current signature)… then back again indoors…?

Not sure if there’s an easier way eg by scaling data from your powermeter - some have the possibility I believe, but doubt it’s allowed if you do virtual races

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I wonder if, after training for 6 months on the trainer with a target power lowered by, let’s say, 10%, I would be able to ride outdoors next Spring with an extra 10% target power !? I don’t know if the large HR increase is a problem with the power I have to sustain, so a kinda muscular problem, or a problem with the ventilation/breathing/oxygenation/temperature, so kinda a lung problem…

Should I try to do the same workouts I was doing outdoors, but targeting the same HR indoors, to estimate the amount of power required to match the effort as close as possible ?

Could you increase ventilation? Since I have two powerful fans blowing at me right beside the open window in a room that is not heated, I do much better indoors, feels better too. Drinking enough is also helpful.

Yes, I open my window :slight_smile: And I bought a Vacmaster last year, in addition to my old Honeywell. I noticed a difference last Winter, but apparently it’s not enough yet. I turn the Vacmaster on after 5 minutes of warm-up, otherwise I would get a cold ! And sometimes I turn the secondary fan on, mostly to my face (the Vacmaster blows on the torso).

Hi Wes, his problem is the inverse of what you suggest. If his signature is set outside then it is too high for indoors and a breakthrough would be nearly impossible. Instead the alternative is to let his signature decline or to adjust it downward then it will make a breakthrough possible to reset his signature.

Instead of biasing the trainer load try to reduce your signature. Go to advanced MPA and see how reducing your TP and HIE affect the MPA curve. If you did what was a really hard effort then you can get an idea of where your signature should be. You can adjust the signature from that then do a breakthrough to set it more realistically.

Also yes indoors can feel harder and if you do not have good cooling that alone can cause your heart rate to go up as it tries to maintain your body temperature. Also there is not as much moving around so you do not get a chance to use different muscles etc.

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Agree and that’s what I tried to say… but may not have been clear

Do an indoor all out effort to failure, trying to have a BT. It won’t be a real BT vs outdoor signature due to whatever causes indoor power to be lower, but he can still go in and get Xert to calculate a signature assuming it was a BT using steps I outlined, then use that going forward

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I fought all year long to regain a decent TP (after being too much focused on HIIT last Winter), it’s depressing to think that I’ll have to set it back by 20-30W :sob:

Another screenshot with another comparison between two “similar” workouts done outdoors and indoors:

  • two weeks ago: one Rock&Roll endurance, outdoors → average power of 216W and average HR of 138 bpm
  • yesterday: one SS@82% - 3x20 min., indoors → average power of 215W and average HR of 150bpm !

As you can see on the picture, the intervals were done at the same power (239W) in the two workouts. With about 147bpm for the R&R one, and about 159bpm for the SS one, during the intervals (3x15min vs 3x20min).

well there are so ways to get clues as to how to set the signature. A while back Armando suggested the formula for (PP-TP)/ HIE should be in the range 28-33 ish. Since PP is a fairly straight forward and anchored then the HIE and TP are the factors to vary. Also it is fairly well known that \heart rate will go up in heat. To keep things into balance you need to drop both HIE and TP to keep them in that range. As I noted that in Advanced MPA you can play with the TP and HIE numbers and see how they act for the indoor ride. You can try to get it to look more like the outdoor ride maybe.

Hum, not sure what to do about it !?
Currently, my PP is evaluated to 870W (haven’t done any workout to test it, for months). TP around 290W, HIE about 22.6kJ. The formula give me a very low result (25), to be in the range I should lower my TP by more than 40W, or lower my HIE to 20kJ. With that, with 40-50W less on my TP, I think that my workouts would be too easy. On the other side, lowering my HIE, would not change the difficulty of the workouts I mentioned above !?

I think it is one good thing you should do to get a good start. It is easy to do all out sprints, do a few and anchor the PP first. HIE (from what my current understanding ) is the rate of use for the MPA. So lower appears to use it faster So one you have a fix on PP the other two are need to move each other to achieve a similar result. ie say PP = 860 then any combo of HIE and TP that gets you in the 28-34 range should be reasonable. It is unlikely your TP has declined a lot indoors vs out but HIE may be affected by the heat, leading to depletion of MPA faster? So a starting point might be something like PP 860, TP 290 HIE 18.24 which is a ratio of 32. By lowering the HIE if using smart workout it would change the duration of the intervals. That is what in my opinion is the strength of XERT, smart intervals that are based upon your current signature. If doing dumb intervals then yes the only lever you have is TP. With smart you have 2 levers you can play with. So it depends. To adjust TP you have to adjust HIE or the equation gets out of whack. So you can maintain PP since it is a simple number again just a number say 860, then drop TP to say 250 and this would suggest a HIE of 19.52. So then once you do the adjustment it should make it easier to hit a breakthrough and get a new signature for indoors.

OK, I may do a “Xert Fitness Test for Breakthrough Version 2” next week, if I remember I did one a few months ago where I reached 950-970W on the sprints… Though, that would put me in the “28-33 range”, and make me cringe hard for the next 6 months, doing my indoors workouts ! :open_mouth:

You could just do your endurance rides by heart rate and stop when you hit your XSS target.

Out of interest, what cooling do you have? IMHO an industrial fan is the way to go.

That’s a big difference in HR. Does it occur right from the start of the workout or does it develop during the workout because of heat, depleting oxygen, etc.?

If the difference is instant, you could double check whether or not your power meter and trainer are indeed set up correctly. A while ago I found out that my trainer was somehow not using the bike PM anymore and also underreporting power, resulting in some pretty tough workouts :hot_face:

Firstly, if you reduce your power targets by adjusting your signature to get more XSS from the workout, you’re in effect biasing your power higher indoors. Counter intuitive but is ultimately the end result.

Secondly, ventilation is trickier than you think. I used to have similar discrepancies. I have found that a big fan, aimed correctly (sometimes a small change can be make a big difference), some heat adaptation and hydration, hydration, hydration make the difference for me. I can generally hit the same targets although long efforts at TP are still a bit challenging for me indoors. In terms of thermodynamics, if your sweat is dripping, you don’t have enough ventilation. You’re cooling the floor and not your body.

Lastly, something else you may want to look at is your floor. If your trainer is on a wooden or soft floor, you could be losing mechanical energy as it asborbs and doesn’t reflect all of your movement. I haven’t seen any tests on this but it something I’ve been wondering about. Would be curious if this was the case for you.

Vacmaster + Honeywell

See the previous screenshots: I started the workouts similarly, the HR fluctuates at the same pace: stable during the intervals… but at different levels !

I already checked that, last year, after I got my second PM, a XCadey, where there was a gap with the power reported by my HT (Direto XR). The good thing is that this PM is adjustable, and after I modified a parameter, it now returns the same power as my HT.
I did several workouts where I was using Xert (EBC) to record the data from the XCadey, and at the same time I was using BigRingVR to record the data from the HT. Overall, I have the same average power, close to 1-2W from each other, with only some spike differences here and there, but probably because Xert records “instant” (1s ?) power whereas I think BigRingVR smooths it on 3s, afair.

Hum, yeah, I sweat a lot, I use a towel to wipe up my face and hands, but after my workouts I have to wring my shirt out, the back is completely soaked. I don’t get that problem when I ride outdoors, my shirt is dry when I get back home… It only gets wet whenever I have to stop for any reason, and as soon as I pedal again, the air flow dries it quickly.
So, yeah, maybe I should play with the ventilation: my main fan is aimed at my torso, the secondary is aimed at my face, when I really need it. Should I have ventilation on the legs ?

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Looking at the fan and listening to your description of how you sweat, it’s clear to me that you aren’t getting enough ventilation and that is the primary reason why you can’t ride at the same intensity indoors as you can outdoors.

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I may try to turn the Honeywell to my back. The Vacmater is so powerful that I only set it on the first speed (of 3 available), and I turn it below my head because I don’t want to get a cold with the potential blow on my throat !

In addition to ventilation (and hydration which Armando mentioned, but doesn’t seem to have generated much discussion), a couple of other factors come to mind - not sure how strongly each is proven though:

  • what position are you in for outdoor rides vs indoor e.g. were your steady outdoor efforts on climbs vs indoor on flat? Would expect different mechanics and efficiency due to different alignment with gravity / position relative to BB, hip angle etc. That can also affect breathing.
  • How stable is your core when pedaling? or how much do you move your bike under you when riding outdoors, even seated? indoors the bike won’t move which again changes the pedal stroke… you may be unconsciously shifting your whole body side to side (slightly) each stroke, which would take more energy for example
  • What gear ratio are you using on the trainer? read an interesting article about the impact of kinetic energy on power output and perceived difficulty (explaining why some people can put out more power climbing but struggle on the flats, irrespective of cadence) so wonder if speed of the flywheel could have an impact? you can google climbing vs time trialing cycling tips… and of course can experiment at home in ERG mode with high and low gears
  • Are results different for ERG vs slope mode - again thinking of changes in pedal stroke due to difference changes in required torque and power throughout the stroke with each option