Training Peaks, wattage, etc

[former lightweight]

Hey folks - I wanted to poll the wisdom of the crowds out there and see if anyone has had any experience utilizing TrainingPeaks for training on the erg?

I know this program is a little analytical, but it has gained so much traction in the cycling world (both with pros and amateurs) I was surprised to see there wasn't more talk about it. I used it in a limited fashion this winter while training and it gave a lot of context to the work I put in on the erg, and what it meant "stress" wise relative to riding the bike and running Any thoughts, users out there?

[donutcritic]

Hey folks - I wanted to poll the wisdom of the crowds out there and see if anyone has had any experience utilizing TrainingPeaks for training on the erg?

I exported data from my logcard and noticed it was formatted quite nicely (CSV file). Did you use this method to import to TrainingPeaks and/or WKO+ (the Windows desktop software)? I'd love to be able to integrate my rowing data with cycling, which is my primary sport.


-jh-

[former lightweight]

Glad I was following this thread, I thought no one would reply!

What I did was derive my FTP in watts as close as I could and then just plugged in intensity factors depending on what the percentage of FTP was for a workout. So... if my FTP (for an hour) was 300w, and I did a workout at an average of 250, the IF is .83. From this I can get TSS and so on.

My 'problem' with the erg is that I think the measuring of watts is way off. I use a powertap on my bike and it is a little frustrating not to have accurate feedback on the erg in terms of what a watt 'costs'. Anyone out there know how the erg actually measures wattage? Is it through a strain gauge or other method?

[Nosmo]

Glad I was following this thread, I thought no one would reply!

What I did was derive my FTP in watts as close as I could and then just plugged in intensity factors depending on what the percentage of FTP was for a workout. So... if my FTP (for an hour) was 300w, and I did a workout at an average of 250, the IF is .83. From this I can get TSS and so on.

My 'problem' with the erg is that I think the measuring of watts is way off. I use a powertap on my bike and it is a little frustrating not to have accurate feedback on the erg in terms of what a watt 'costs'. Anyone out there know how the erg actually measures wattage? Is it through a strain gauge or other method?

The watts on the erg is actually very accurate. It measures the power put into the flywheel. (by knowing the moment of inertia and the flywheels acceleration and deceleration, it can accurately measure the power going into, and dissipated by the flywhee0. The gory details here: http://www.atm.ox.ac.uk/rowing/physics/ergometer.html

What I think you are missing is that one cannot put as much energy into the ergometer flywheel as one can put in to the cranks or rear wheel of the bicycle. Rowing is much less efficient then cycling so the power numbers will be lower for the same physical stress. Also the rowing machine does not measure the work moving your body up and down the slide, so there are some additional losses you don't have on the bike.
So if you want to get comperable TSS values for the erg and for cycling, you will have to multiply the power on the erg by some factor (there is probably an offset and a multiplier).

What that value is I really don't know and it probably will change for each individual somewhat.

The training peeks methods are really useful because cycling is so intermittent--the power levels can vary wildly. On the erg that is not the case so calculating one's TSS is not nearly as necessary. It would be as if you cycled without wind and without hills.

[former lightweight]

Nosmo, thanks for the link to the description of how power is measured on the erg... interesting stuff! The mechanical efficiency of the bike definitely something I've thought about relative to the erg and is a good point. Probably the most important difference is the relative torque you have to generate to obtain 'similar' watts... on the bike you can spin 90 rpm, reducing torque on each pedal stroke and creating a more aerobic/efficient system. On the erg I'm guessing the 'torque' number is going to be much higher, meaning a less efficient (and more difficult!) motion. I was a collegiate lightweight and my best time for 2k was 6:21, or a little over 400 watts... when I started racing bikes I could do that number for over 10 minutes... it was a real eye opener!

In terms of training, when I plug numbers in for rowing in TrainingPeaks I usually assume that the 'normalized' power and average power are exactly the same (ie, as if you were doing a time trial on a bike), and then I usually add a certain factor in to compensate for the missing TSS points. I'm thinking it gets me close enough!

[Nosmo]

6:21 as a college lightweight! I'm impressed.
I guess you live in a relatively flat place because around here for most time trials the power is a long way from constant.

[former lightweight]

Thanks, I was very fortunate to row for a good EARC team. I'll definitely see major fluctuations in power as I'm riding, but provided that I'm pedaling consistently the normalized power (the power that represents the best estimate of the physiological cost of the effort) and average power work out to be pretty much exact. I've pasted an example below from a 30min test on the bike I did in September:



Edit - got the data to post-



I've transitioned back to some erging now that it is cold out, so I'm having to get used to staying in much narrower range in terms of the numbers I see on the erg... which is much harder in terms of focus!

[donutcritic]

So if you want to get comperable TSS values for the erg and for cycling, you will have to multiply the power on the erg by some factor (there is probably an offset and a multiplier). What that value is I really don't know and it probably will change for each individual somewhat.

Do you have a sense for what this formula would be? I'm guessing there's some way of looking at SPM + Watts which can normalize the data between rowing and cycling.

thanks!

[Nosmo]

Do you have a sense for what this formula would be? I'm guessing there's some way of looking at SPM + Watts which can normalize the data between rowing and cycling.

I don't use a power meter on my bike so I don't have direct experience, but....
I read somewhere that measuring the power at the handle resulted in reading 25W more then given by the flywheel. One could also estimate the losses moving the body up and down the slide. See this: http://www.atm.ox.ac.uk/rowing/physics/ ... #section13

Don't know how close that would get you, but it is a start.

[pierre]

Getting back on the erg or on water after a longer hiatus than I thought, I'd like to keep on using trainingpeaks as part of my training.
How to upload the csv to trainingpeaks? (I downloaded rowit 1.1 in order to get a csv).

[lucasjw]

I'm excited to be getting a SkiErg soon and was interested to see if anyone has been using it with TrainingPeaks. Good to see it may be possible to get the power data into TrainingPeaks from the Performance Monitor, though, I'd have settled for HR data alone recorded separately from the PM.

Regarding tracking power, IF, TSS, etc. with SkiErg, it's been discussed here about applying an offset factor to a pre-established FTP value (e.g. take a cycling FTP of 300 and multiply by .75). A better technique that applies the concept of FTP more literally (and thus accurately) would be to establish your FTP on the SkiErg independent of any cycling FTP (or other sport). Use a good test protocol and retest over time to refine and update an FTP value that applies to your skiing. This process of establishing a skiing FTP would account for the different physiological demands and responses in skiing, plus the different economy of skiing. Make sure to enter the new FTP and related zones in TrainingPeaks specifically for XC-ski so when you add XC-ski workouts the data is calculated on the right FTP value.

Now about the SkiErg power measurements…. From reading about the Performance Monitor so far I haven't found good information about how it gets it's power numbers. I saw the link provided in this discussion that goes into the physics of ergometers, but it's still not clear how the physics are measured and recorded in this unit. The Performance Monitor will display the force curve, which implies that force is being measured and power could be calculated easily and accurately. In other information about the PM it is stated that a calculation is used based on time to complete 500m, specifically: Watts = 2.80/(sec/meter)^3. Aside from saying 2.8 is used as a constant, there's no additional information given. While this equation can be derived from what's presented in the physics of ergometers link, there is no mention of changing that constant for different levels of damping. I'm hoping this calculation is simply a post-hoc way of estimating power from velocity, but again, it's not clear how the power measurement or calculation is actually being done. If it's calculating and recording power on a second by second basis (or other small time interval), the power data--including data that affects normalized power and IF--can be better calculated. But if data is really only calculated at 500m intervals, then it's hard to account for surges in pace (sprints, short intervals, etc.) that can have significant impacts on NP and IF but less so on average power. So in the end I'm left hoping that whatever the measurement method is, it's reliable so that the power data would at least be useful and informative on one particular machine.

I hope that's helpful for others looking at using the SkiErg data with TrainingPeaks. If anyone's got information about how the measurement and recording of power data is actually done on the SkiErg that would be helpful. (Even if I just happened to miss this info in a rather obvious place.)

[Bob S.]

The damper settings (or better, the drag factors) do not effect the monitor readings. The erg calculates the energy expended by measuring the rate at which the wheels slows down, using three magnets on the wheel. The watt to speed conversion equation is based on the speed of a 4 rower shell (4x or 4- I can't remember which).

The skierg may well use a different conversion factor, since the 2.8 is an arbitrary value, specific to the 4x or 4- shells. A recent posting under skierg describes why the shierg shows different drag factors than the rowing ergometer (an extra baffle in the case), so it would not be surprising if a different conversion factor were used in the power to speed conversion equation.

Bob S.

[lucasjw]

Thanks, Bob, for the details. I'm new to the ski ergs and have no experience with rowing ergs, either. I was doing more reading and it sounded like the power measurement was better than simply the speed-based formula I found. The reported speed calculation being based on a calculation from power then makes sense. I assumed all along the ski speed reported was only ballpark.

[Bob S.]

Thanks, Bob, for the details. I'm new to the ski ergs and have no experience with rowing ergs, either. I was doing more reading and it sounded like the power measurement was better than simply the speed-based formula I found. The reported speed calculation being based on a calculation from power then makes sense. I assumed all along the ski speed reported was only ballpark.

Whoops, I see that you read my earlier post before I edited it. That first version was erroneous. I went back to the Skierg forum and found the post that I mentioned. I had misremembered it. It was about drag factor and not the power/speed equation. However, as I implied in my corrected post, there is a good chance that the skierg monitor uses a conversion factor other than 2.8 - one appropriate to skiing rather than rowing. The 2.8 is arbitrary after all and is way off for comparison with single sculls (too fast) and a bit off for 8s as well (too slow).

Bob S.