# Still Time to get in on Stryd a Power Meter for Running!



## martowl (Dec 31, 2010)

This is a power meter for runners! Looks like it is going to be great and already works with Ambit2 and Ambit3. Still room left on Kickstarter here. More info from Stryd here and a preview from DCRainmaker here.

A photo from the website that shows the device working on an Ambit. Apparently Suunto has Power available in the Run modes so this will work out of the box. Garmin does not have Power implemented in Run mode so one would have to use a cycle mode.

I preordered from Kickstarter and the company is in my hometown!


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## roots_n_rocks (Apr 5, 2013)

It is very good to have some kind of effort measurement for running other than heart rate with all those limitations.
But on the other hand i don't understand how a pod, attached to to short or your shoe will give you power metrics.
Cycling powermeters calculate DIRECT force applied to the pedals, not CALCULATED force based on some algorithms.

I believe that this product is a very expensive advanced suunto app.
I am playing around with some physics formulas and suunto apps and i have created an app that shows you running power.
I haven't try it in practice due to injury, but even if the numbers are not correct, as far as they are consistent i would have an independent metric.


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## martowl (Dec 31, 2010)

roots_n_rocks said:


> It is very good to have some kind of effort measurement for running other than heart rate with all those limitations.
> But on the other hand i don't understand how a pod, attached to to short or your shoe will give you power metrics.
> Cycling powermeters calculate DIRECT force applied to the pedals, not CALCULATED force based on some algorithms.
> 
> ...


I hear what you are saying and agree in principle, it is the software that is critical...read DCRainmakers' hands on, it is pretty impressive, especially the hill efforts.


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## wydim (Feb 26, 2012)

yeah, Cycling power is MEASURED, and is useful to have an universal comparison variable for cycling effort. It's great because it automatically factors windspeed, incline and other course variables to compare the true best efforts between individuals

Running power, on the other hand would have to be CALCULATED from many inputs (running speed or pace, incline, wind speed and direction, leg length, etc)

What this company is selling is indeed an algorithm (formula) that could be "easily" reproduced or copied (there was a thread on this forum about trying to discover the formula for EPOC because it wasn't available in real time on the Ambit. With enough trial and error, everyone could get near the running power that this company has figured. 

as roots_n_rock said : as long as it's consistent it's useful tool (a triathlete who's well balanced between cycling and running should?/could? have the same Running and Cycling power). What do you guys think ?


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## martowl (Dec 31, 2010)

wydim said:


> yeah, Cycling power is MEASURED, and is useful to have an universal comparison variable for cycling effort. It's great because it automatically factors windspeed, incline and other course variables to compare the true best efforts between individuals
> 
> Running power, on the other hand would have to be CALCULATED from many inputs (running speed or pace, incline, wind speed and direction, leg length, etc)
> 
> ...


If you guys can do this it would be great! I would certainly rather use an in house app. I will have the Stryd so I can be a tester if anyone wants to make a stab at this.


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## wydim (Feb 26, 2012)

martowl said:


> If you guys can do this it would be great! I would certainly rather use an in house app. I will have the Stryd so I can be a tester if anyone wants to make a stab at this.


My programming skills are VERY, very, very limited. So is my interest in running power. But still, I appreciate innovation and companies like Stryd.

I read many comments in DCrainmaker's thread. Some people have brought up interesting limitations(?) of their device : running surface (pavement, sand, mud) and wind (among many others) will not be taken into account (or will they ?)

If I was running trail (with many ascents-descents) I would use gradient corrected running pace (Strava has it). For other factors, I would let the years to come to show us a real powerMETER (as opposed to powerCALCULATOR).

keep us posted !


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## roots_n_rocks (Apr 5, 2013)

You don't need to have programming skill to built an suunto app.
You just need some ideas, some basic math knowledge and .... patience.

I have create an Running Power app which doesn't show downhill power.
I have start creating a Running Power app that somehow calculates downhill power (in not a scientific way)
I have created a Ground Contact Time app.
And finally the most useful app for trail running is the Gradient Corrected Speed like the one wydim mentioned.

There is not much programming there, basically math.
I started testing with them but due to injury it will take some time.
I don't aim and don't care to be precise, but i want some consistent data to use and see changes.

I will post the results of my tests later this spring.


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## martowl (Dec 31, 2010)

roots_n_rocks said:


> You don't need to have programming skill to built an suunto app.
> You just need some ideas, some basic math knowledge and .... patience.
> 
> I have create an Running Power app which doesn't show downhill power.
> ...


Let me know if you want anymore testing, you can send me the code to load and I can keep the app private. I would be most interested in Gradient Corrected Speed


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## wydim (Feb 26, 2012)

Martowl,

Do you have a Strava account ? if not, you can create one for free (strava.com) and your suunto moves will update automatically to strava analysis platform (after you allow it via movescount). Strava has the "gradient corrected pace" graph available for post-run analysis. Or maybe you want it in real time ?


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## roots_n_rocks (Apr 5, 2013)

Since i don't want to rush things and it is gone to take a while until i start running again,
i have made the app public: 
Grade Adapted Speed - App at Movescount.com

I am not sure if the way i guide the watch to understand when is is uphill and when downhill is correct,
but if is seems wrong, let me know, i have another idea.

Ideally you should have a flat grade adapted speed line in your graph which would be equal to your avg speed.


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## martowl (Dec 31, 2010)

wydim said:


> Martowl,
> 
> Do you have a Strava account ? if not, you can create one for free (strava.com) and your suunto moves will update automatically to strava analysis platform (after you allow it via movescount). Strava has the "gradient corrected pace" graph available for post-run analysis. Or maybe you want it in real time ?


I have a Strava account but given some of the hills we have here, I consider it fairly inaccurate. When moving downhill on steep technical trails the app simply thinks you are running on a concrete sidewalk, which is not the case. The downhill estimates are way off in my opinion. I am not convinced the uphills are so good either when the grade gets steep enough that running is literally not possible. We have many hills and mountains that fit these categories.

I am Bradley Olwin on Strava


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## martowl (Dec 31, 2010)

roots_n_rocks said:


> Since i don't want to rush things and it is gone to take a while until i start running again,
> i have made the app public:
> Grade Adapted Speed - App at Movescount.com
> 
> ...


I will give it a try, Thanks. A real time readout from the app would be what I am looking for to train.


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## danielp27 (Oct 8, 2014)

martowl said:


> I will give it a try, Thanks. A real time readout from the app would be what I am looking for to train.


hi martowl, 
i was also looking for a real time app which provides kind of power calculation. i found this very interesting article, about GOVSS
http://www.physfarm.com/govss.pdf

the golden cheetah community are implementing the calculations in their software
https://groups.google.com/forum/#!topic/golden-cheetah-users/zJuNFOeTP9w

source code is GNU, can be found here:
https://github.com/GoldenCheetah/GoldenCheetah/blob/master/src/GOVSS.cpp

great job by them. for now i have taken just the power metric. there are some other metrics i would like to integrate in the future.

maybe you can take a look at it. i guess the app will be as good as the altitude and pace data are. it will probably work better if the watch has an altimeter, or if one is using a foot pod. i tested it yesterday with my ambit 2s, and i think it is interesting. for a certain pace, one needs more watts running upwards than downwards, and this kind of stuff. i do not know if the results can be comparable with those of Stryd. but this solution is cheaper  and can be already used. 
only thing i miss, is that movescount would allow to export data to trainingpeaks or strava. but app data is not exported, AFAIK

this is the app:

running power GOVSS - App at Movescount.com


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## PabloAlarcon (May 18, 2013)

nice thead and really interesting stuff specially the power metrics. With my little knowledge what I know about power metric is that in cycling is used mostly because is more reliable than other metrics since is not affected by variables like heart rate is for example . I guess my question is How should power be used in running ? or how can I take advantage of this metric. Nice app by the way!!!


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## martowl (Dec 31, 2010)

PabloAlarcon said:


> nice thead and really interesting stuff specially the power metrics. With my little knowledge what I know about power metric is that in cycling is used mostly because is more reliable than other metrics since is not affected by variables like heart rate is for example . I guess my question is How should power be used in running ? or how can I take advantage of this metric. Nice app by the way!!!


One great way to use this is interval training, especially for me for hill intervals that I usually do on trails. I would like to ensure that my effort is similar across intervals and as I get more tired going from the first to last my HR will increase and this may cause a reduction of effort.

A second one for me would be consistent effort on hills and not too hard.

I used a power meter when I was racing and training for bike racing and it was the only metric I used in my training. Much more useful than HR.


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## martowl (Dec 31, 2010)

danielp27 said:


> hi martowl,
> i was also looking for a real time app which provides kind of power calculation. i found this very interesting article, about GOVSS
> 
> great job by them. for now i have taken just the power metric. there are some other metrics i would like to integrate in the future.
> ...


Thanks for this, I grabbed the app and since I already sunk my $ into Stryd I will compare. If the app is as good as Stryd we can all save $ and use only the one device.


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## PabloAlarcon (May 18, 2013)

thanks Martowl for the reply and thanks to Danielp for the app, it's really nice to have this forum and people that contribute this way


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## danielp27 (Oct 8, 2014)

as far as i remember, in GOVVS they calculate the power equivalent to your lactate threshold, by reading power in a race of at least 10km, and not longer than 1h. Based on that power, one can define training zones, and so on. I'll investigate once of these days ;-)


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## PabloAlarcon (May 18, 2013)

Hi daniel, let me know if you change the app
, so I can test it !! Martowol also test and he es very experienced so his feedback should be helpful tunning the app. As I said to you in movescount I think the app work but probably to sensitive,as you said, so and smoothed version with and average could make it easier to read en real time. Saludos!!


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## danielp27 (Oct 8, 2014)

hola Pablo, 
actually i have a new version that i have not tested yet. i have not made it public yet. it is a little bit silly that i cannot update the old one. suunto should take a look at that. apps are done to be updated, arent they?
anyway, i have been thinking that best way to get the app behave smoother, is to calculate a moving average.

even in the GOVSS document i linked above, Mr Skiba says:

"It should be noted that Coggan (2003, 2006) has advocated using a 30 second rolling average to smooth the power data and facilitate analysis, which is sensible given the many physiologic processes have 30 second half-lives".

so it makes even sense from a physiologic point of view ;-)

i am going to replace my speed and slope calculation, by this code below. the rest of the app is the same as before. we'll see... if you create a copy of the app, you can just edit the code.


```
speed = SUUNTO_DISTANCE_TOT[30]*1000/30;


if(SUUNTO_SPEED < 1)
{
  slope = 0.0;
}
else 
{
   slope = SUUNTO_ALTI_DIFF[30]/Suunto.sqrt(Suunto.pow(1000*SUUNTO_DISTANCE_TOT[30], 2)-Suunto.pow(SUUNTO_ALTI_DIFF[30], 2)) ;
}
```


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## PabloAlarcon (May 18, 2013)

Hi danielp I just ried the new version of the power app, I set up the previous version and the new one to see the diferences but all I see now is a flat line in both of them I dont know what happened or what I did wrong. heres the move. I just changed the code for the new one th previos one I didn touch it. heres the move. I rename the new version to RUNNNG POWER.

PabloAlarcon's 1:03 h Trail running Move


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## danielp27 (Oct 8, 2014)

hi Pablo, 
you see a line because a couple of times something went wrong with the calculation (pace very very high or very very low), and you got some power values very low. it is strange, did you lose gps connection during workout? i will check the formula.

if you zoom in before the peaks, then you see the curve. i think these are the original app, and your new one. did you use the 30secs moving average as i posted? i am disappointed, both are almost the same. it is not smoother.... and in ambit apps you cannot have more than 30 points in an array, so it is not easy to take more points.

i will give it a thought. thanks for testing!









edit: this is one of the peaks. from: 27.30 to 29.30 there is data at all. this causes some weird values when data is available again. what happened there? did you pause the workout? maybe we can make the app more robust in such a case:


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## PabloAlarcon (May 18, 2013)

Hi daniel, i went out with a friend slower than me and I was pausing the exercise to wait for him, this could be the reason we see the power graph for both apps as a flat line, maybe it is taking the pauses into acount to make the calculations...dont know for sure, but i guess it is somehing related to the pauses because if I select the parts between pasuses i can see the graphs as they should be, and the Spike it's where i just waited for my friend but didnt pause the exercise, i just stood there waiting, so that spike it's also messing up the calculations.


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## PabloAlarcon (May 18, 2013)

PabloAlarcon said:


> Hi daniel, i went out with a friend slower than me and I was pausing the exercise to wait for him, this could be the reason we see the power graph for both apps as a flat line, maybe it is taking the pauses into acount to make the calculations...dont know for sure, but i guess it is somehing related to the pauses because if I select the parts between pasuses i can see the graphs as they should be, and the Spike it's where i just waited for my friend but didnt pause the exercise, i just stood there waiting, so that spike it's also messing up the calculations.


well i just checked it again i think the pauses are not the problem but the time i'm just standing without moving, that generates the spikes, drop outs actually that messes up the graphs, if I zoom out leaving the drop out out of the selection i can see the apps graphs ok


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## danielp27 (Oct 8, 2014)

Ok, we will check this issue with the laps. about the oscillations, i kind of understand what the problem is. Instant altitude functions in the watch are very innacurate. It is documented in many forums. Thats why you can find many apps calculating the vertical speed, because the calculation provided by the watch is not good. Most of these apps use a tail average of altitude to estimate a smooth instant altitude. Probably the easiest would be to get an app which provides a reasonably smooth vertical speed curve, and use it within my original app, replacing the built in vertical speed. I will do some research and let you know.


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## martowl (Dec 31, 2010)

Daniel and others who are interested. Here is the zoom from my Tempo Run. I was a hard effort, I have my MaxHR effort set to anything above 167 bpm, my threshold is probably in the low 160s. I included the Power output, HR and altitude, the move is here if you want a better look. This is my third run with the Powermeter, the original app. Notice in the middle where the grade is constant as was my effort but the graph for power spikes up and down considerably. If this could be smoothed out more it would be great. let me know what to try.


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## danielp27 (Oct 8, 2014)

hi guys, 
thanks for testing. 
i have a new version of the app. right now is just about fixing the oscillations, nothing else. you can find it here
RUNNING POWER GOVSS - App at Movescount.com
i have replaced the built in vertical speed calculation by this one
Vertical Speed 30s AVG Mod5 - App at Movescount.com

i wont be testing it before the weekend, but you can. 
if you guys remove the old one from your lib, i will remove it.

have fun!


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## martowl (Dec 31, 2010)

danielp27 said:


> hi guys,
> thanks for testing.
> i have a new version of the app. right now is just about fixing the oscillations, nothing else. you can find it here
> RUNNING POWER GOVSS - App at Movescount.com
> ...


Thanks danielp27, I am running today will remove the old app and replace with the new one. This is great, although off topic I looked at the Fenix3 forum, mostly complaints about issues. Here most of the time we are trying to improve functionality


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## roots_n_rocks (Apr 5, 2013)

martowl said:


> Here most of the time we are trying to improve functionality


Yeah, doing Suunto's job, who seems to believe that ghost runners and interval timers are all it's customers want,
or writing apps like these :
RUNNING EFFICIENCY - App at Movescount.com
http://www.movescount.com/apps/app31-How_hard

I wonder, have suunto developers (who write the two above apps), yet recovered from their effort ?????


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## danielp27 (Oct 8, 2014)

yes, those apps are pretty simple. but lets be fair, the magic is that we have an API to create apps ourselves. and it works pretty well from day 1 (not as garmin one. which looks much more powerful, but also according to the comments, is kind of a beta)
i only wish suunto would improve the API a little bit: a function to create laps, a couple of additional "beep" functions (one for too fast, and other for too low, for instance). no big things at all. 
and then, i wish they would implement a way to export the app data into the FIT file, so that for instance my calculated power data can be read by strava, training peaks, and so on.


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## PabloAlarcon (May 18, 2013)

danielp27 said:


> hi guys,
> thanks for testing.
> i have a new version of the app. right now is just about fixing the oscillations, nothing else. you can find it here
> RUNNING POWER GOVSS - App at Movescount.com
> ...


Great Daniel I 'm running today so I see how it goes and I'll post it here later


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## PabloAlarcon (May 18, 2013)

well here is my move with the lates ver. of the app. I selected a section of the trail where i has some steep parts mixed with some easy rolling path but always going up. The graph does look smoother I posted the old version vs the new one so you can see how it looks like

old power app: PabloAlarcon's 0:56 h Trail running Move









new power app: PabloAlarcon's 0:55 h Trail running Move


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## danielp27 (Oct 8, 2014)

thanks Pablo and Brad. 
still too many oscillations. i am going to test with a new approach. no more moving averages, i am going to use a low pass filter for the vertical speed. it is much simpler, and more flexible. i am using this implementation of a filter:
Frame Rate-Independent Low-Pass Filter

one can play with the smoothing factor and see what happens. In the app I have configured smoothing=100. probably too aggressive... (the higher the value, the smoother the vertical speed. smoothing =1 means, no filtering at all) . 
i have been playing with an excel sheet and the vertical speed curve is smoother now. but i am not sure how much delay this will introduce.

you can test it here:
Running Power GOVSS - App at Movescount.com


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## wydim (Feb 26, 2012)

roots_n_rocks said:


> Yeah, doing Suunto's job, who seems to believe that ghost runners and interval timers are all it's customers want,
> or writing apps like these :
> RUNNING EFFICIENCY - App at Movescount.com
> http://www.movescount.com/apps/app31-How_hard
> ...


Guys, I applaud what you're doing : Trying to create more value for yourself and maybe other interested in these apps. But just realize that you're the 0.1 % that needs/want these apps. It would be very expensive for Suunto to please that 0.1 % to perfection. And they still have to survive as a company to get the next Ambits out and provide for the future generations of Explorers ! I'm not trying to defend them. I'm pretty bummed that an Android app is still not available today (I mean, people in their basement have made wonderfully sophisticated Android apps !)

I just hope that you're having fun while doing this. If not, what's the point of doing it, right ?  cheers !


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## martowl (Dec 31, 2010)

danielp27 said:


> thanks Pablo and Brad.
> still too many oscillations. i am going to test with a new approach. no more moving averages, i am going to use a low pass filter for the vertical speed. it is much simpler, and more flexible. i am using this implementation of a filter:
> Frame Rate-Independent Low-Pass Filter
> 
> ...


Here is mine from yesterday as well with a good hill for measure. The app is doing a great job of measuring watts when I walked short sections of the steep hill. Even though my pace reduced to walking I was moving and working hard where the watts peaked. In this zoom I show pace, altitude and power. I will try the new version tomorrow, I have an 18 mi/25k run to do. Thanks again.


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## martowl (Dec 31, 2010)

Seems smoother now danielp27. Here is a zoom and a full view of my last run on Sat.


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## martowl (Dec 31, 2010)

Here is another example, danielp27, the app appears to be working very well. I used the new Ambit update to run intervals today. The power was constant between each interval but you can see my HR going up especially with the 3rd interval. This is exactly what the app is great for, to maintain a constant power output. The zoomed in screenshot is below where I zoomed in on the intervals.


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## danielp27 (Oct 8, 2014)

hi, thanks for testing. yes, i have seen it works pretty well if the slope is constant: in flat ground, or in trails where one is always ascending (or descending). it does not work so well in hilly ground, though. with the new filter, the power is not very responsive to changes in the slope. it takes quite a lot before the app knows, that the slope has changed. i am thinking on a couple of changes in how i filter vertical speed. 
i am also thinking in introducing a kind of target , so that the app would beep if we are beyond a certain threshold. 
anything you would like to see there? ideas?


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## morey000 (Dec 12, 2013)

watching app development... with enthusiasm. Great work Daniel.
And yeah- it's a little confusing when you go to the app zone, as to which is the most current version. blah!


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## danielp27 (Oct 8, 2014)

Yes you are right. I gave the same name to all apps because i thought it would be easy to delete the old ones eventually, but it is not. This is my first public app, i had no experience with the whole process. From now on i will add a version number to the name  
Silly that one cannot edit existing public apps as in any other app store.


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## PabloAlarcon (May 18, 2013)

Hi ! well I've using the power app latest version and it gives a nice smooth line in movescount heres my lates move with the the app:

PabloAlarcon's 1:32 h Trail running Move


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## danielp27 (Oct 8, 2014)

hi Pablo, 
great that you are happy with the performance of the app. i havent released any new version. i have been doing some local changes to try to improve accuracy for me, without success. :-( i have an ambit2s, without barometer, and for me the app is not so smooth, even with the very high smoothing factor i configured. 

i cannot test it, but i am pretty sure you can do your smoothing factor smaller (you've got a ambit2 with barometer, right?), it will be still very smooth, and the app will be more sensitive to changes in the slope. 

for my case, i have a couple of ideas. given that i cannot get an accurate real time power estimation (it is not a problem with the watch. it is just the way gps can estimate altitude), i am thinking of calculating a lap average power. 
let me know if you miss something in the current version of the app. you and brad are using the app a lot, so maybe you have a feeling if under certain circumstances the app does not behave as you expect.


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## PabloAlarcon (May 18, 2013)

Hi, here's another run, amore runnable circuit where I tried to use Power to pace the run. First I tried to keep a moderate to hard effort based on feeling, and while doing that I more o less set a Power nuber of 300 and tried to keep that value. What I noticed was.

-when at a sustain effor on a easy incline, as the trail gets steeper an the pace slows downs the power rises ...nice!

-on a long easy donhill inmediately after and uphill if i want to keep the effort and power I have to speed up and the app reacts well on this!! nice!
-when running at a sustain effort Power value and I geto to very steep climb where i have o stop and start "power walking"...even when my percived effort is the same or higher because of the incline, the power drops significantly ( as my pace obvously does) and stays very low antil aI reach a section where I can star running again, then the value stabilizes. here's s capture of what I'm saying:

Alti-power






alti-Hr-power






alti-pace-power








I guess that is obvious tha while the pace slows down I applied less power on each step..but on the other hand the effor is high because of the incline and that should result in a higher pwer output...

here's the link to this move http://www.movescount.com/moves/move57251249


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## danielp27 (Oct 8, 2014)

hola Pablo, 
i think power goes down, because you are descending the previous hill too slow. in your move, 28:20, power is already down, 50W, even before starting running uphill. I this is because your pace at the time is 8:13 min/km. the power formula expects that you accelerate downhill to keep the effort. not easy though? 
once that you begin to run uphill, power begins to increase. at 29:30, power is around 200W. it takes sometime before rising, because of the filtering we did in the app for the virtual speed to avoid oscillations. vertical speed is smoother, but it is delayed by the filter. 
i set the default smoothing to 100 (because of my lack of barometer). but i think 10 should be OK for a watch with barometer. 100 is ok for long hills where slope is not changing frequently. but when slope changes, it takes sometime to stabilize. not so smart :-(
i am testing a new, smarter(?), approach without filtering. i might do this app public before the weekend. i will let you know.


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## martowl (Dec 31, 2010)

Let me know as well danielp27, I am using as is Pablo. Less smoothing might be a good option as I have an Ambit3Peak.


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## danielp27 (Oct 8, 2014)

hi, 
need volunteers 
my usb charger has broken, two of the pins got stuck :-( the watch is less than one year, i hope suunto takes care of it, i havent done anything strange with the charger. 
anyway, i have a new version i have not tested yet. i have check the formulas with excel against an old move of mine and they look fine, stable and with much less delay. 
i hope i didnt do any mistake when programming the app. if somebody is willing to try, i think the best idea is to let both apps run at the same time, so that they can be compared. 
this is the new one:
Running Power GOVSS V2 - App at Movescount.com

i have fixed also a small issue i saw with the power calculation. not a big thing though. it could produce slightly higher readings at the beginning of the move.


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## martowl (Dec 31, 2010)

danielp27 said:


> hi,
> need volunteers
> my usb charger has broken, two of the pins got stuck :-( the watch is less than one year, i hope suunto takes care of it, i havent done anything strange with the charger.
> anyway, i have a new version i have not tested yet. i have check the formulas with excel against an old move of mine and they look fine, stable and with much less delay.
> ...


I will run tomorrow and test both apps.


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## PabloAlarcon (May 18, 2013)

Hi daniel...I'll test both apps today and publish the move here later.


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## PabloAlarcon (May 18, 2013)

hi daniel here's the move from yesterday PabloAlarcon's 0:53 h Trail running Move with both apps new version and old one


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## danielp27 (Oct 8, 2014)

Hi Pablo,
cool, how did it feel? Actually after making the app public i realized i forgot to change the value of alpha. It is 0.02, which is rather small, it means it filters again a lot. The whole point was to filter less, to make the app more sensitive when slope changes frequently.... what i tried in my excel file was alpha =0.1
i hope i get a replacement for my cable soon....


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## PabloAlarcon (May 18, 2013)

danielp27 said:


> Hi Pablo,
> cool, how did it feel? Actually after making the app public i realized i forgot to change the value of alpha. It is 0.02, which is rather small, it means it filters again a lot. The whole point was to filter less, to make the app more sensitive when slope changes frequently.... what i tried in my excel file was alpha =0.1
> i hope i get a replacement for my cable soon....


hi daniel i changed the alpha value to 0.1, the other variables should be 0 right? because I didnt change those.


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## danielp27 (Oct 8, 2014)

hola Pablo, 
i have been looking some other moves done with the latest version of the app from some other colleagues. and the fact is that it follows altitude changes pretty fast. maybe it does not need adjustment. difficult for me to see. in the end it pretends to be a measurement of effort. so it is the one who is running, who can tell, if the number matches his/her effort...
with your move is difficult for me to say. you go up, and up, and up.... and then down, and down, and down, .... impressive ;-)

if you want to play with alpha: yes, you dont need to change anything else. it has to be changed within the first if condition ( if(SUUNTO_DURATION==0))
the alpha does a little prefiltering, because distance data is not available every second. the idea behind was that the alpha cleans a little bit the data, and the 2nd filter is which really calculates the slope. 
a big alpha (close to 1) produces too many oscillations, a small alpha (close to 0) should tend to delay the signal (power increases some seconds after beginning a hill, for instance).


----------



## martowl (Dec 31, 2010)

danielp27, Here are two moves done with both apps, I found in one move they differ considerably and in the second move the newer app had issues, where zooming in shows detail but appears as a straight line zoomed out. Screenshots below and link to move1, link to move 2. For move #2 I downloaded the data by USB, all my other moves are syncing via the iPhone app.

For both graphs only Power is shown with the newer app highlighted in orange


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## danielp27 (Oct 8, 2014)

Hi Martowl, i saw your move 2. Actually it is working fine. But for some reason the power has some peaks, and the scale of the graph adapts automatically. That is why you just see a line. But if you use the zoom tool, you will see is fine.
actually i think the app v2 is working pretty well. It reacts very quickly to changes in the slope. There is a move from a fellow this weekend who did some uphill series, and the newest app reacts perfectly, while with the previous version the hills got filtered. This is a zoom of your move, after the last peak

View attachment 3639258


Suunto has sent me a new cable really fast. I will check where the peaks are coming from. I am willing to test myself!


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## PabloAlarcon (May 18, 2013)

Hi daniel and Martowl, here are two moves with the V2 of the power app, I didn't change the alpha o it's just as Daniel published the app. I see i really copies the altitude profile very well and reacts pretty well whereas the previous version is, in this casi in this move too smooth. This move is mostly an urban trail by the highway, I was running on dirt and it has easy and long ups and downs, not as my usual hill circuit where I go up and down all he time with some steep ups and short donwhills, now I hav to try the V2 in that scenario.

move 1 PabloAlarcon's 0:44 h Trail running Move

you can see how power copies the alti profile


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## danielp27 (Oct 8, 2014)

hola Pablo, 
thanks for testing. 
i am working on a v3. somehow i think that v2 is not good enough. but the reality is that the changes i have tried are not performing better as of now. 
i will keep you posted. 
together with v3 i will publish a "grade adjusted pace" app i have done. it calculates how fast you would run on flat surface when applying the same power you have.


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## martowl (Dec 31, 2010)

danielp27 said:


> hola Pablo,
> thanks for testing.
> i am working on a v3. somehow i think that v2 is not good enough. but the reality is that the changes i have tried are not performing better as of now.
> i will keep you posted.
> together with v3 i will publish a "grade adjusted pace" app i have done. it calculates how fast you would run on flat surface when applying the same power you have.


Thanks danielp27. I have several runs with your app, some with a lot of elevation changes. You can see them in my profile. If you want I can post them here as well. I am using your app and recording on all of my runs.

I will gladly start using v3 when it is ready.
Brad


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## danielp27 (Oct 8, 2014)

martowl said:


> Thanks danielp27. I have several runs with your app, some with a lot of elevation changes. You can see them in my profile. If you want I can post them here as well. I am using your app and recording on all of my runs.
> 
> I will gladly start using v3 when it is ready.
> Brad


Hi Martowl,
thanks, it is not neccessary to post the runs here.
if during one of your runs you felt at some point that he app was not working fine, then it can help me to get a xlsx file of the move. I have a couple of excel workbooks with which i test somewhat the app. I can check speed and altitude around the point and see how the app reacted.


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## danielp27 (Oct 8, 2014)

hi, 
version 3 is here, and also the grade adjusted pace app i mentioned
Running Power V3 - App at Movescount.com
Grade Adjusted Pace - App at Movescount.com

to be honest, i don't know how well they will perform for you guys having an ambit with barometer (ambit2, ambit3 peak). i don't (i have an ambit2s). this is a great handicap for slope calculation. GPS altitude is not accurate, and it introduces lot of noise in the altitude. now the most important thing about the app is the slope calculation.

as of now i don't think i wll be doing changes in the slope calculation anymore. this is as good as i can go with my 2s (suunto: if you are reading this, you can provide me the gear so that i can test further ;-) )

i have to filter elevation data so that i get rid of most of the noise, but not too much that small hills get filtered too. in the end, in my ambit it is more or less usable where gps accuracy is better (no trees, buildings, not many u-turns, and so on).

i say this, because i have optimized omega for the data i have (mine ;-) ) 
and it might be that the app filters too much for some of you (but i dont know. it might as well work fine). 
should it be the case, then you can create a copy of the app and modify this line:

```
omega=0.005;
```
i you have the feeling it filters too much (lets say, a small hill was not taken into account) I think omega=0.02 should be OK for watches with barometer - just guessing (the smaller omega, the more filtering). or maybe 0.015 or 0.01 if you see that power gets too noisy with 0.02

the more you filter the slope, less noisy will be the power calculation. but also there is a risk that small hills are missed. 
for slope calculation i am using this algorithm, which i think is performing very well. I don't need to do a prefiltering at the beginning anymore:
http://deltamotion.com/peter/pdf/AlphaBetaGammaCode.pdf

now about the grade adjusted pace app. it is basically the same app as above, with an additional calculation: first instant power is calculated. and then, based on that power, pace is calculated, asuming slope is 0. Similar to what strava calls GAP (but how strava calculates GAP is not public).

for this final calculation, one would need to loop until a solution is found. but there are no loops in suunto apps. therefore i implemented manually two iterations of an algorithm called Secant method - Wikipedia, the free encyclopedia . i have checked offline, with excel, and the secant method converges very fast to the solution in this case. with two iterations should be accurate enough most of the time (within 1sec). 
what i said above regarding omega, applies also here. you should use for GAP calculation the same omega value which is ok for power.

have fun testing, nice weekend!


----------



## mercuir0 (Mar 24, 2015)

danielp27 said:


> now about the grade adjusted pace app. it is basically the same app as above, with an additional calculation: first instant power is calculated. and then, based on that power, pace is calculated, asuming slope is 0. Similar to what strava calls GAP (but how strava calculates GAP is not public).
> have fun testing, nice weekend!


hy daniel,

thanks for your great apps... will start testing them on a ambit 3 peak. i really like the profound research you did and especially the documentation in your code!!
i have one idea / question: what about adding a third app that calculates the GAP at VO2max? this should stay more or less constant over the whole run and especially it's average value should be a great help in observing improvements over a long period of time. polar uses something called running index, but that only takes in account pace and hr.... you'r app could even do better.

and a second question: cadence should also have an impact in running power, shouldn't it? is there some paper you know that may could help to accoun for this?


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## danielp27 (Oct 8, 2014)

hi Mercuir, 
i didn't know about running index. i have checked, and it looks similar to VDOT by Jack Daniels. i would also be interested in something like this. it is just that i havent found a paper for that. i pretend to actually implement GOVSS, but not the power, but the score actually. it is a replacement for TRIMP, which uses power instead of HR for calculation. but that is not quite the running index. if you find some useful information how this running index might be calculated, let me know. 
about the cadence vs power thing, i havent read anything. i have read a lot about cadence, and actually i went from about 140spm to above 180spm about two years ago. 
it is probably not what you are looking for, but i found this article the other day:
running commentary?: Running strides Part 1: ground and aerial contact times

it uses physics+empirical data to guesstimate ground contact time , vertical displacement, and some other things. good stuff. i implemented for fun a couple of them. you can take a look.


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## martowl (Dec 31, 2010)

danielp27, this is awesome, I will test it out this weekend, thanks for all of the hard work and information. You should upgrade to a peak and sell the sport, the peak watches are good deals on Amazon now.


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## wydim (Feb 26, 2012)

martowl said:


> danielp27, this is awesome, I will test it out this weekend, thanks for all of the hard work and information. You should upgrade to a peak and sell the sport, the peak watches are good deals on Amazon now.


The last time we saw these kind of deals on an Ambit watch (it was ambit2) and the ambit3 was announced a couple of weeks later.

I do not plan to buy it because my 2 is still working flawlessly, but still... can't wait to see if Suunto has listened to the customers !


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## danielp27 (Oct 8, 2014)

mercuir0 said:


> what about adding a third app that calculates the GAP at VO2max? this should stay more or less constant over the whole run and especially it's average value should be a great help in observing improvements over a long period of time. polar uses something called running index, but that only takes in account pace and hr....


hi again Mercuir, 
have you read about Efficiency Factor? it is pretty similar to the running index you have mentioned, i think. the GOVSS document explains how to calculate normalized running power out of instant power. therefore it is pretty straightforward to implement the same for running. i will give it a try 

http://home.trainingpeaks.com/blog/article/efficiency-factor-and-decoupling


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## mercuir0 (Mar 24, 2015)

danielp27 said:


> hi again Mercuir,
> have you read about Efficiency Factor? it is pretty similar to the running index you have mentioned, i think. the GOVSS document explains how to calculate normalized running power out of instant power. therefore it is pretty straightforward to implement the same for running. i will give it a try
> 
> Efficiency Factor and Decoupling | TrainingPeaks


i just stumbled upon this:
http://run-fit.com/runningeconomy.pdf

what also may be interesting is firstbeats paper collection:
White papers | Firstbeat
Research and publications | Firstbeat

i think that calculating the speed at vo2max by using gap and %vomax should be a quite good indicator for running efficiency


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## raducanmihai (Aug 10, 2012)

@danielp: As I understand, Ambit series shows horizontal distance instead of actual distance. I'm not familiar with Suunto apps so I'm asking you: is there a way (technically) to write an app for Ambit 2 and Ambit 3 Peak (the ones that have barometric altimeter) that shows 3D distance and 3D pace?


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## danielp27 (Oct 8, 2014)

danielp27 said:


> hi,
> version 3 is here, and also the grade adjusted pace app i mentioned
> Running Power V3 - App at Movescount.com
> Grade Adjusted Pace - App at Movescount.com


hi, i think the omega i have chosen sucks. it does not really work fine for me. and i have check a couple of moves from this weekend and it makes weird things after some hills. so in the end it is worst than the previous version was. i have created two copies, this time with a , i hope, more realistic slope calculation. 
http://www.movescount.com/apps/app10121999-RUNNING_POWER_v4
http://www.movescount.com/apps/app10121997-GAP_v2


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## danielp27 (Oct 8, 2014)

raducanmihai said:


> @danielp: As I understand, Ambit series shows horizontal distance instead of actual distance. I'm not familiar with Suunto apps so I'm asking you: is there a way (technically) to write an app for Ambit 2 and Ambit 3 Peak (the ones that have barometric altimeter) that shows 3D distance and 3D pace?


hi Radu, 
yes, i understand the same thing. actually when i contacted suunto regarding this, they confirmed this point, with the only exception of using a pod, as far as i remember. 
i forgot to mention it on friday, but running power v3 (and now v4), calculates 3D speed. once you have calculated the slope, it is pretty straighforward with some trigonometry. you got this calculation in this line of the app: 

```
/* 3D speed */
  speed = speed/Suunto.cos(Suunto.atan2(slope,1));
```
So you can do a copy of the app, and remove everything after that line (keeping parens), and do:

```
RESULT=speed;
```
you will have an app showing 3d speed, in m/s. if you want pace or other units, you have to do some calculations.

as for the distance, once you have the speed, it is also quite straightforward. 
- you make a copy of your 3d speed app 
- add a variable called "distance", with initial value = 0. 
- after speed calculation, you add a distance calculation. distance = speed * time, but time is always 1 second, therefore:

```
/* 3D speed */
  speed = speed/Suunto.cos(Suunto.atan2(slope,1));
  distance = distance + speed;
```
- return your calculated distance as result:

```
RESULT=distance;
```
this calculated distance is in meters. for miles, km, and so on, you have to do some math again. 
the calculations will be as accurate as the slope calculation is. so much much better with the ones that have barometric altimeter ;-)


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## raducanmihai (Aug 10, 2012)

Thanks Daniel. I'll try writing it this weekend and keep you posted. 

PS: My first name is Mihai (Michael/Mike in English) and my surname is Raducan. 

From Galaxy S5 using Tapatalk


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## danielp27 (Oct 8, 2014)

danielp27 said:


> hi, i think the omega i have chosen sucks. it does not really work fine for me. and i have check a couple of moves from this weekend and it makes weird things after some hills. so in the end it is worst than the previous version was. i have created two copies, this time with a , i hope, more realistic slope calculation.
> RUNNING POWER v4 - App at Movescount.com
> GAP v2 - App at Movescount.com


GAPv3 should take into account if you are using imperial or metric units (not tested!  )
GAP v3 - App at Movescount.com


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## gasteps (Aug 26, 2015)

Hey Daniel-- Finding the GAP V3 app very useful with my Ambit3 Peak. Excellent training tool. I'm wondering if it's possible to write a GAP app that averages over a lap? I'd like to use the app to run intervals which I measure over the lap average. At the moment I use regular pace lap avg, but of course when confronting hills, it becomes a little annoying. Let me know what you think!

Adam


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## danielp27 (Oct 8, 2014)

Hi Adam, sorry man, i told you in movescount I'd implement it but haven't done it so far. Sure, i will do it. Just give me some days, i dont have access to a computer till next week. I'll inform here when it is ready.
I'm glad that the app is being useful for you.
EDIT
PD a little bit offtopic, but, may I ask what for a hr strap do you have? A suunto one? I wanted to see the GAP graph in one on your moves. And it has raised my attention that your energy consumption graph is very different to what i usually see. In my moves energy consumption is pretty similar to hr. In your case it comprises just some straight lines. I'm curious. Thanks!


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## danielp27 (Oct 8, 2014)

Stryd can finally be bought. it has a 20$ discount right now. i have been following the product for a while. i liked the idea, worked for a while on an app without much success and was therefore expecting the device to be released. 
https://www.stryd.com/order

it is funny that, while at the very beginning suunto ambit seemed the best pairing option (dcrainmaker used a ambit for his review), finally they will be more garmin focussed. 
all four videos showing how to pair stryd to your gps watch, belong to garmin watches. even the very old 310
https://www.stryd.com/support

besides, there is an incompatibility issue between stryd and suunto. it seems suunto is aware of the issue, and will be fixing it, ..., but only for ambit3 onwards. 
Compatible watches/devices - Support - Stryd

this means that my ambit2s is out of scope. very disappointed.... :-(

PD: 
i have just found this:


> Stryd power meter is fully compatible with Suunto Ambit2 and Ambit3 watches. To get started with a Stryd power meter add a pod to search _("Power pod")_ for your Ambit and a power data field in the watch's running mode.


in suunto web:
Stryd Kickstarter - Suunto

published on 3 März 2015. so everybody who bought an ambit2 after that date because of this article, will be also very very disappointed.


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## roots_n_rocks (Apr 5, 2013)

I think this is a very expensive heart rate monitor.
Power estimated and not measured, is not power.


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## martowl (Dec 31, 2010)

Ok guys the OP is finally getting his Stryd. Mine has shipped, here is a tidbit about Suunto compatibility as well.

Suunto Ambit 3 Peak, Ambit 3 SportSupports power and heart rate in running mode. Stryd's power meter and heart rate monitor are treated as two separate devices. Stryd can connect to the watch as either a power meter, or a heart rate monitor, not both.

Suunto representatives have indicated that they plan to release a firmware update tosupport Stryd with both power and heart rate by the end of Oct. 2015.


The information in the box above was relayed to me in an email from Stryd.


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## martowl (Dec 31, 2010)

Ok guys the OP is finally getting his Stryd. Mine has shipped, here is a tidbit about Suunto compatibility as well.

Suunto Ambit 3 Peak, Ambit 3 SportSupports power and heart rate in running mode. Stryd's power meter and heart rate monitor are treated as two separate devices. Stryd can connect to the watch as either a power meter, or a heart rate monitor, not both.

Suunto representatives have indicated that they plan to release a firmware update tosupport Stryd with both power and heart rate by the end of Oct. 2015.

The information in the box above was relayed to me in an email from Stryd.


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## paul1928 (Jul 27, 2013)

Took my Stryd for its first run today. Had it mounted on a Garmin HRM3 strap, sitting above my Suunto strap and sensor.
So far, so good - but I'll be looking forward to the Stryd:
- being able to send HR _and_ power to the Ambit 3 so that I don't have to wear two straps
- being able to send R-R/IBI HR data (the unit's firmware currently doesn't support this) so that EPOC/PTE work.


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## costaxo (Jan 3, 2014)

martowl said:


> Ok guys the OP is finally getting his Stryd. Mine has shipped, here is a tidbit about Suunto compatibility as well.
> 
> Suunto Ambit 3 Peak, Ambit 3 SportSupports power and heart rate in running mode. Stryd's power meter and heart rate monitor are treated as two separate devices. Stryd can connect to the watch as either a power meter, or a heart rate monitor, not both.
> 
> ...


It would be nice if you would do some runs with both the stryd sensor and the running power app so we could compare how accurate the app really is.
Unless from what I understand and seen on another user you can only use the stryd sensor now just for running power and no HR logging on ambit 3.
I'm using the running power app on my runs and it seems interesting and from what I understand stryd is using the HR data to get the power data so basically it's the same thing just coded different??


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## martowl (Dec 31, 2010)

costaxo said:


> It would be nice if you would do some runs with both the stryd sensor and the running power app so we could compare how accurate the app really is.
> Unless from what I understand and seen on another user you can only use the stryd sensor now just for running power and no HR logging on ambit 3.
> I'm using the running power app on my runs and it seems interesting and from what I understand stryd is using the HR data to get the power data so basically it's the same thing just coded different??


The Stryd uses accelerometers to get most of its information, in fact it started without HR. So I think that the Stryd is likely more sophisticated with the data it acquires. Whether that translates into any real life difference is a worthwhile question. I will wear the Stryd and use danielp27's app on several runs. Unfortunately I have a bad cold so it will be a few days. Soon, Suunto should release the update so I don't have to wear two hr belts.


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## gasteps (Aug 26, 2015)

Hey Daniel-- Now I've been slow to reply. I'm using the 4iiii viiiiva for a hrm.

Now I'm interested in the Power V4 app you have. It seem pretty consistent for my output. I'm wondering if it's possible to make either/both the GAP v3 and Power v4 with "Lap Average"? This would help interval training immensely. Also, the instantaneous values are tough to comprehend on the run. Would love these in averages over a lap!

Thanks!

-- Adam



danielp27 said:


> Hi Adam, sorry man, i told you in movescount I'd implement it but haven't done it so far. Sure, i will do it. Just give me some days, i dont have access to a computer till next week. I'll inform here when it is ready.
> I'm glad that the app is being useful for you.
> EDIT
> PD a little bit offtopic, but, may I ask what for a hr strap do you have? A suunto one? I wanted to see the GAP graph in one on your moves. And it has raised my attention that your energy consumption graph is very different to what i usually see. In my moves energy consumption is pretty similar to hr. In your case it comprises just some straight lines. I'm curious. Thanks!


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## danielp27 (Oct 8, 2014)

gasteps said:


> I'm interested in the Power V4 app you have. It seem pretty consistent for my output. I'm wondering if it's possible to make either/both the GAP v3 and Power v4 with "Lap Average"?


hi Adam, 
i have begun with the running power app. please test, i haven't tested it myself. if it works fine, the GAP one should be pretty straight forward. 
RUNNING POWER LAP AVG V1 - App at Movescount.com


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## bruceames (Jul 20, 2013)

martowl said:


> The Stryd uses accelerometers to get most of its information, in fact it started without HR. So I think that the Stryd is likely more sophisticated with the data it acquires. Whether that translates into any real life difference is a worthwhile question. I will wear the Stryd and use danielp27's app on several runs. Unfortunately I have a bad cold so it will be a few days. Soon, Suunto should release the update so I don't have to wear two hr belts.


What are your impressions so far on this?

I'm thinking of getting one, but have a few questions.

1) does it wear on the chest or clip on to your shorts/shoes? I've read mostly that it clips on to your shorts. But how could it measure HR from there?

2) I would like to use it only to measure power and continue to use the Suunto strap for HR. Can I do that? Don't want to wear two belts.

3) Is the device updateable via firmware?  I would sure hope so, since the algorithm has lots of room for improvement, given that there is a lot of guesswork and variables involved and (so far) very few runners providing power data that could be used to tweak it.


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## R1P (Sep 30, 2009)

As to the device, it comes as a chest strap and measures HR and power. No need for a second strap. As for its updating capabilities, I understand via firmware. 

I'm also considering getting one. 


Sent from my iPhone using Tapatalk


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## bruceames (Jul 20, 2013)

So can I pair it with the A3 as both a power meter and HR belt? Martowl mentioned earlier that you have to choose. If so, then that would be a dealbreaker for me since I use HR primarily for pacing and this new power data will have to "earn" its right to be used as the primary pacing metric.

As for the field 1 watch display, I current have speed (top), HR (middle) and chrono (bottom). I suppose I would give up chrono and move it to the second display and put power there instead (and have the 3s and 10s power averages in one of the secondary displays, unless I think the 3s or 10s is better than current power).

Another concern with having it as the belt is that:

1) will it be as comfortable as the A3 belt?

2) I currently replace the straps every 6 months or so and just bought several replacements (8 of them actually for only $7 each at REI), since the contacts wear out over time (I use Firstbeat software to monitor the error rate to change the battery/strap as needed). Wouldn't want to have to buy a new unit or pay a high price for replacement straps. Maybe the pod fits 3rd party straps?

3) Does the Styrd pod have memory like the A3 pod?

4) On my hikes I use a viiiiva dual ant+/BT strap for connecting to my Garmin handheld as well. Will the Stryd connect to both ant+ and BT devices at the same time?


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## martowl (Dec 31, 2010)

bruceames said:


> So can I pair it with the A3 as both a power meter and HR belt? Martowl mentioned earlier that you have to choose. If so, then that would be a dealbreaker for me since I use HR primarily for pacing and this new power data will have to "earn" its right to be used as the primary pacing metric


The latest firmware update permits both HR and Power coming from the Stryd. HRV seems to be recorded and is similar to the Smart sensor belt.

As for the field 1 watch display, I current have speed (top), HR (middle) and chrono (bottom). I suppose I would give up chrono and move it to the second display and put power there instead (and have the 3s and 10s power averages in one of the secondary displays, unless I think the 3s or 10s is better than current power).

I have found that 3s avg for Power is the best for me when attempting to gauge effort. Don't forget that you can use power as a workout metric too.

Another concern with having it as the belt is that:

1) will it be as comfortable as the A3 belt?

Definitely not. I am not sure I can wear the belt for an ultra, the Suunto belts are the most comfortable I have ever worn. The Stryd belt is similar to the Garmin and the Stryd device is about the size or a bit bigger than the Garmin HR transmitter.

2) I currently replace the straps every 6 months or so and just bought several replacements (8 of them actually for only $7 each at REI), since the contacts wear out over time (I use Firstbeat software to monitor the error rate to change the battery/strap as needed). Wouldn't want to have to buy a new unit or pay a high price for replacement straps. Maybe the pod fits 3rd party straps?

The pod will fit any standard snap in strap but not the Suunto as the Suunto transmitter is much smaller. Crap, I wish I would have seen the REI deal, I would have bought several too! Mine only last 6 mo or so as well.

3) Does the Styrd pod have memory like the A3 pod?

No and the Ambit only remembers one belt, which I like to use at the gym so I have to repair it often.

Overall, I am not convinced the Stryd will help that much for my training. I do not tend to look at my watch that often when I am running.

4) On my hikes I use a viiiiva dual ant+/BT strap for connecting to my Garmin handheld as well. Will the Stryd connect to both ant+ and BT devices at the same time?

Yes it transmits both ant+ and BT so you could connect two devices.


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## bruceames (Jul 20, 2013)

Thanks for the info Martowl. I think I'll wait on this. Seems like a lot to give up (mainly comfort-wise) for something with unknown accuracy. I was hoping it was a clip-on pod. Anyway using HR to monitor training and racing pace is working well for me. In the meantime I think I'll check out danielp27's app.


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## user_none (Jan 11, 2015)

Snip...



bruceames said:


> 2) I currently replace the straps every 6 months or so and *just bought several replacements (8 of them actually for only $7 each at REI)*, since the contacts wear out over time (I use Firstbeat software to monitor the error rate to change the battery/strap as needed). Wouldn't want to have to buy a new unit or pay a high price for replacement straps. Maybe the pod fits 3rd party straps?


Just wanted to snip this out for anyone else that may have missed it. Replacement straps, the same size as what comes with an Ambit3, for $6.93 each! If you're in the US, it's time to stock up on straps.

Suunto Smart Sensor Heart Rate Strap - Medium - REI.com


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## danielp27 (Oct 8, 2014)

hi, 
i have just found this
https://groups.google.com/d/msg/golden-cheetah-users/Mz1B3P_B8SE/BfjSeZXUAQAJ








the graphic shows the correlation between power calculated using GOVSS algorithm, and stryd. Golden cheetah is a open source project which supports GOVSS and also can fetch data from stryd. so this data can be measured and compared GoldenCheetah

it does not look bad at all. i wonder if somebody has simultaneously used stryd and the running power app to compare data? the running power app uses the GOVSS formula.
RUNNING POWER v4 - App at Movescount.com

i have an ambit2s which does not have a barometer. the app does not perform well without a barometer. but i got the feedback that with a barometer it behaves better. i was tempted to order a stryd, but i abandoned the idea when they changed the concept from a weareable to a chest strap.


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## martowl (Dec 31, 2010)

danielp27 said:


> hi,
> it does not look bad at all. i wonder if somebody has simultaneously used stryd and the running power app to compare data? the running power app uses the GOVSS formula.
> RUNNING POWER v4 - App at Movescount.com


Here is mine, I will re-add the app and do several more. There were major differences that I could see. Let me know if you want the files to re-plot the data.
bradolwin's 0:17 h Running Move

The Stryd device was not working initially as well as it is now. I will return and post a few more runs but I will run today, tomorrow and over the weekend with both.


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## martowl (Dec 31, 2010)

danielp27 said:


> hi,
> i wonder if somebody has simultaneously used stryd and the running power app to compare data? the running power app uses the GOVSS formula.
> RUNNING POWER v4 - App at Movescount.com


Here is today's run. The app had issues at the very beginning so I zoomed in a bit for a better comparison. The app underestimates power when I am hiking hills that are too steep to walk. Shown in orange is the Stryd, white is your app and the altitude for reference. The move is here.


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## martowl (Dec 31, 2010)

Here is another comparison with the graph below. I had to zoom in again as the initial power reading from the app was way off. They look similar.


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## danielp27 (Oct 8, 2014)

thanks a lot for the analysis Brad, 
so summarizing the app and stryd are similar when you run, but not when you power walk. stryd seems to reflect better your perceived effort. this is a zoom of your down hill section:

View attachment 7172410

in this section both correlate pretty well. i wonder if so much filtering stuff i added to the app might be in the end counterproductive.
about the power walk section: another movescount fellow, Pablo, already commented on this. all the enegy calculations are based on this document

ARTICLES | Journal of Applied Physiology

they estimated enegy cost by measuring 10 runners on a treadmill inclined. in the document they mentioned that a test was interrupted if blood lactate accumulation was higher than 4mm. and it seems this happened particularly at the highest positive slopes. even 4 people could not perform the test at high slopes. i think this is why the formula is not working in those sections. you are working anaerobically in those sections, and this case was out of the scope of the study. i wonder if there is another study estimating cost when anaerobically running uphill..... probably stryd have done their own analysis so that the formula is valid on a wider range of situations.

i have created a new version of the app, removing the filtering
running power feb2016 - App at Movescount.com

it will be much noisier now, therefore i have created two additional apps, which perform a 3-sec-rolling average resp 10-sec-rolling average. with powermeters this seems to be the standard procedure to get a smooth output. 
RUNNING P3 FEB2016 - App at Movescount.com
running P10 Feb2016 - App at Movescount.com

i won't be testing them, because without barometric altitude the app does not perform well. if any of you guys have problem with them let me know.

BTW when creating them i have realized that the apps seem to be not compatible with traverse and vertical. bummer. for me looks like suunto is eventually phasing out apps. shouts in apps are not displayed in movescount timeline, and apps used by a certain user are not shown anymore (before the timeline was introduced, this info was visble in the user profie page). Newer devices do not support the whole API, ... that makes an upgrade for me less appealing.


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## PabloAlarcon (May 18, 2013)

Hi daniel I'll be testing the new apps this evening on my hillrun


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## martowl (Dec 31, 2010)

I will test as well. I was going to ask if we could get 3s and 10s averaging. Thanks! Will post along side Stryd.


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## costaxo (Jan 3, 2014)

Like I said before, daniel's app is very interesting. I still use it but I can't tell much out of the data only check it out after the run on MC. I don't use it for trail running and hills. Not quite sure how that works. And if it works properly. One thing I've noticed is that the data isn't steady. What I'm trying to say is that one would expect when doing intervals in the track to see a more linear diagram without spikes since the effort I'm putting every 100-200m is the same considering the pace/time. Instead it fluctuates a lot from 500watts to 460watts when considering the pace it should be steady @ let's say 500watts
I don't use a stryd belt but I guess the data output would be the same.
Here's an example of 1k repeats on track @ 3.17 avg
View attachment 7180946


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## danielp27 (Oct 8, 2014)

Hi costaxo, 
I cannot open your attachment. 
If it oscillates, it means either pace or altitude oscillates too. Have you checked how is the altitude graph in movescount? 
Which ambit do you have, one with barometer?


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## costaxo (Jan 3, 2014)

I guess I don't have enough posts to post an image here. Not sure if the same happen with a link.
Anyway here's a link to the activity.
costa_t's 0:31 h Running Move

I hope it works now.
Cheers!


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## costaxo (Jan 3, 2014)

There's not much altitude change in the exercise, but I'm using the altimeter profile. Pace should be steady since the I had pretty steady passes on the 100m 200m 400m mark.


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## danielp27 (Oct 8, 2014)

If you show vertical speed you'll see what i mean. It is continuesly oscillating between -4 and +4m/min. Weird, because a track is supposed to be flat. I dont know if that kind of oscillations are normal with a barometric altimeter. anyway, this is what causes the fluctuations in the app. The app thinks you are running uphill and downhill alternatively. And you need less power to run downhill if you keep a constant pace


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## costaxo (Jan 3, 2014)

Oh I see what you mean. I wonder using barometric profile for the altitude whether the results will be better.


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## danielp27 (Oct 8, 2014)

You definitely have to use the barometer for the app to work accurately. Gps altitude is ok as a rule of thumb, but not for real time slope calculation


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## costaxo (Jan 3, 2014)

I'll give it a try tomorrow and I'll report back!


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## bruceames (Jul 20, 2013)

danielp27 said:


> BTW when creating them i have realized that the apps seem to be not compatible with traverse and vertical. bummer. for me *looks like suunto is eventually phasing out apps*. shouts in apps are not displayed in movescount timeline, and apps used by a certain user are not shown anymore (before the timeline was introduced, this info was visble in the user profie page). Newer devices do not support the whole API, ... that makes an upgrade for me less appealing.


I hope not, but the signs point to them being indifferent about them. We'll really find out where they stand when the A3 peak replacement comes out this summer.


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## martowl (Dec 31, 2010)

Here is my latest run with the Stryd and apps, Daniel, your app either 1 sec or 3sec avg looks nearly identical to the Stryd. Great work!!!
bradolwin's 1:29 h Trail running Move

Here is a screenshot with Daniels 1s app in orange and Stryd in white


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## danielp27 (Oct 8, 2014)

thanks Brad,
indeed they seem to be correlated...

one question for you: are you finding stryd really useful? can you do something like, "ok, lets going to run this trail while trying to keep 250W. ". 

i am not an expert at all. but for what i have read, the advantage of using power is that you are able to calculate your critical power. and depending on that value, you can sort of calculate the most apropiate target power for a certain distance. similar to what one would do with HR, but being HR more subjective because it has a lag and depends on several other factors. but i have the feeling, that keeping a constant power is not really easy, is it?


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## costaxo (Jan 3, 2014)

Daniel an update I switched to baro profile today for running in the track and the results are way better!
I think the app works perfect now and depicts the watts usage! It's great for post running analysis imo.
Awesome! Thx for this man! And from what martowl is saying the data must be really close to stryd!
View attachment 7196890


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## roots_n_rocks (Apr 5, 2013)

There is a thing i don't understand with running power.
That is power when going downhill.

I have a REAL power meter on my bike. If i push the pedals it registers power. 
If i don't push the pedals, as it usually happens when i ride downhill it doesn't.
The reason is that when i go uphill or on flat terrain i have to overcome gravity to move. 
When i move downhill, then gravity becomes my friend and i don't have really to do anything.

The same thing i feel in running. When i go downhill, basically i try not to fall no my face and i don't put really any effort. 
Gravity gets me down. My low heart rate is a very good indicator of how low effort (if any) i put to go downhill.

So, why does stryd and this suunto app show power when someone going downhill,
while a REAL power meter doesn't ?


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## danielp27 (Oct 8, 2014)

roots_n_rocks said:


> If i push the pedals it registers power.
> If i don't push the pedals, as it usually happens when i ride downhill it doesn't.


when walking, if you dont push "the pedals" , you dont move  . 
it is true that downhill HR decreases, but also power does. when cycling downhill you could even reach your rest HR if given enough time. but this does not happen when running downhill (at least not for me: i am far from being at rest when running downhill)


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## martowl (Dec 31, 2010)

roots_n_rocks said:


> There is a thing i don't understand with running power.
> That is power when going downhill.
> 
> I have a REAL power meter on my bike. If i push the pedals it registers power.
> ...


I think that power is appropriate when going downhill for me, and in fact, may be underestimated. You are definitely using muscles to slow down or alter your course and this results in power output. I cannot go downhill as fast as possible as I would do serious bodily harm. My HR drops way down when going downhill but...if I push the downhills harder I can get my HR up (having to run with a group doing 7:30 min/mile on a downhill trail for example) and my power up. I have collected quite a bit of power data and I believe this may be a tremendous help during long races. My effort by HR at the beginning of a race is probably much better than late in a race when I am exhausted. By racing with a constant power, I hope to maintain more consistency in racing. I am running a 50k with friends this weekend and will attempt to run with constant power to see how it works. I will let you know.

Check my post below where at the end of the run it is downhill but we were increasing the pace and the power output went up...a great indicator of the effort.


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## martowl (Dec 31, 2010)

danielp27 said:


> thanks Brad,
> indeed they seem to be correlated...
> 
> one question for you: are you finding stryd really useful? can you do something like, "ok, lets going to run this trail while trying to keep 250W. ".
> ...


I agree with you and I have collected enough data now to attempt a run at constant power...time to experiment and see what happens. I have to admit I will probably sell my Stryd, your app is great and as far as using power in real time goes, I don't see enough differences to make wearing the Stryd worthwhile. I am very thankful for your work on this!


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## danielp27 (Oct 8, 2014)

martowl said:


> I am running a 50k with friends this weekend and will attempt to run with constant power to see how it works. I will let you know.


this one calculates the average running power during current lap. might be useful 
RUNNING Plap FEB2016 - App at Movescount.com


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## martowl (Dec 31, 2010)

Check this one out...probably my last run with Stryd as Daniel's app is working well. Major kudos to Daniel!
bradolwin's 8:32 h Trail running Move


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## danielp27 (Oct 8, 2014)

martowl said:


> Check this one out...probably my last run with Stryd as Daniel's app is working well.


thanks Brad. it is right, they do look very similar. 
but both of them seem to oscillate a lot, dont they? is the information provided by them useful while running?


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## bruceames (Jul 20, 2013)

For my part I can't really monitor both power and HR. I have to go by one of the other, and the power readings are too variable and unreliable compared to HR. I know my heart is going to have 'moods' depending on rest and many other factors, but after a mile or two I'll have an idea of what it's capable of and proper 'baseline' pacing (relative the grade of the hill, if any).

However average power per lap will be very useful (as I use the ave HR app as well and it gives me a good idea of performance during the last lap) and thanks for coming up with that app Daniel.


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## j--l (Mar 22, 2012)

Question for Stryders if I may. If one would wish to use the power data outside MC, is the power data in the export files? Or better yet is it passed via the API sync e.g. to sporttracks.mobi or TrainingPeaks? I believe the power data from the Power App is only available in the MC? Or am I totally off with this?


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## danielp27 (Oct 8, 2014)

j--l said:


> I believe the power data from the Power App is only available in the MC?


you are right. power data is only visible in MC. it cannot be easily exported, it wont be included in file when exporting the move.


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## danielp27 (Oct 8, 2014)

hi , 
would some nice ambit2 or ambit3 peak owner test at the same time these two versions of the app? i have done a small change so that the app is compatible with traverse (and also with ambit2r and ambit3r, but for these two will not be very useful because of the lack of barometric altitude). it is not compatible with ambit3vertical or ambit1. these two do not support Pow function. i think the app will be somewhat slower and it might have bigger oscillations. but i would like to see if this is actually so (thinking now of a traverse upgrade)
running p traverse feb2016 - App at Movescount.com
running power feb2016 - App at Movescount.com

thank you in advance

PS i have found a workaround so that the app is also compatible with the vertical, even if it does not support pow function. but vertical does not support SUUNTO_USER_HEIGHT . therefore i have manually entered my height, 180cm. it is not a big deal, height is just used for Aero contribution, which is a very small part of the calculation, and, anyway, it is an estimation. so why bother. but anyway, you can enter your own height. vertical app is here
running p vertical feb2016 - App at Movescount.com


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## gasteps (Aug 26, 2015)

danielp27 said:


> hi ,
> would some nice ambit2 or ambit3 peak owner test at the same time these two versions of the app?


Will do. Just installed all of them. I have a lot of runs between 10k training with harder efforts coming up, and a 50k at ridiculously slow pace too. Hope this helps with a wide range of data. You can "harvest" them all on my MC profile if you'd like: Username: Gasteps. Or just in the app usage page under my username.

Some have complained about oscillation in data and said that it's "useless". I think it's best to keep bike power in the back of the mind here, as they are different animals. One is an actual strain gauge, the other is an algorithm predicting values on multiple data inputs which happen to correlate. Nevertheless, a number is a number for a reference point, whether it's called a watt or "BustMyButt" correlative value, so who cares. Where they are similar is they are both instantaneous values which will oscillate and be basically worthless displayed as raw data, and both solve for the inconsistent data of heart rate by ditching it. So, for the oscillation problem, a 3-second average is better, if one really needs real-time feedback. However lap (aka rep) average or workout average is the sweet spot for this data, bike or run, whether it's showing actual watt values or just some consistent X value. We're not trying to power anything with the wattage anyway. Ok most of us. I recommend two readings, 1) if time strapped: A Power Primer | Cycling with Power 101 | DC Rainmaker (google it, can't post links yet), 2) if a data geek like me: Training and Racing with a Power Meter, 2nd Ed.: Hunter Allen, Andrew Coggan PhD. Just keep in mind watt for a runner with Stryd, Daniel's app, etc should be translated to BustMyButt Value and won't power any TVs. It will however give you the exact same feedback mechanism on your effort within margins of error (strain gauges are not 100% accurate/efficient either). These are used to make stronger decisions about your training. They will help INFORM your decisions, not make the decisions for you! Ok off soap box....

Daniel, you're a rock star with this. Keep this up!


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## danielp27 (Oct 8, 2014)

gasteps said:


> Will do. Just installed all of them. I have a lot of runs between 10k training with harder efforts coming up, and a 50k at ridiculously slow pace too. Hope this helps with a wide range of data. You can "harvest" them all on my MC profile if you'd like: Username: Gasteps. Or just in the app usage page under my username.


thanks gasteps. Pablo had already made some runs for me and now i have seen yours. id say that the traverse app correlates well with the original one. anyway i have given up the idea of buying a traverse. i win the barometric altitude, which is nice to have, but i lose lot of features compared to my 2s. and the vertical is too expensive for me. so no need to test further. 


gasteps said:


> keep in mind watt for a runner with Stryd, Daniel's app, etc should be translated to BustMyButt Value and won't power any TVs. It will however give you the exact same feedback mechanism on your effort within margins of error (strain gauges are not 100% accurate/efficient either). These are used to make stronger decisions about your training. They will help INFORM your decisions, not make the decisions for you! Ok off soap box....


you provided lot of useful info. love the BustMyButt name  just my two cents, this is a white paper by stryd team containing protocol to calculate critical power:
https://docs.google.com/a/stryd.com/uc?authuser=0&id=0B2cVpyCz02TSVUoxRDBmMThGODg

as for the app: all credit goes to researches mentioned in the app


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## danielp27 (Oct 8, 2014)

Hi,

i haven't written here in a while. I moved to the dark side, i am developing apps for garmin now 
my friend tronen (https://www.watchuseek.com/member.php?u=938066) found a bug in the app as well as in golden cheetah. he reported it to them and they fixed it. and now i have decided to fix it in my app too. I will be writting the same app for garmin, and i thought it was a pity that the fix is not available here. besides for some reason my userID is not displayed in my old apps (suunto angry because I moved?  ). this kinds of annoys me. by releasing this my name is back 

enjoy

RUNNING POWER 2017.10.07 - App en Movescount.com


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## costaxo (Jan 3, 2014)

thank you daniel!


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## danielp27 (Oct 8, 2014)

And this is the one calculating the lap average
RUNNING POWER LAP 2017.10.07 - App en Movescount.com


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## Bento Trail (Nov 10, 2020)

Thanks @danielp27 .This is a great app. Is this stiil ok, or the formula is off by now?(2020) Thank you


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