Automated technique evaluation?

[FooTheBar]

Hey!

I'm rowing at a local gym several times a week and since I'm a Maker/Hacker guy, I started to think how I could add some sensors to the erg to help be improve my technique.

The first thing that came to my mind was a sensor for the seat position. This could give me the length of each stroke so that I know if my strokes are constant or if I'm always at the same position at the catch.

The second interesting information would be the handle position (only the distance to the flywheel, not the vertical height) which I then could compare to the seat position. If I move the handle at the catch too long without moving the slide, I could visualize this to the rower so the he knows that his connection was weak. Similarly, at the beginning of the recovery, the handle should move a lot towards the front before the slide should start to move.

Has someone built something in this direction? The erg only gives rather limited information through the force curve which is rather hard to interpret and does not give hints on how to improve.

[jackarabit]

Stroke length can’t be obtained by measuring seat travel. ErgData (a Concept 2 enhancement of PM capabilities) calculates stroke length from the interval between acceleration pulses from the flywheel tach.

The amplitude of the force curve is a graphic presentation of the onset, increase, decay, and coincidence of force applied thru the handle by three major levers: leg extension, back extension, and arm flexion. Think three sine waves in and out of phase on a scope. I think the collective result is a useful “visual” for examining stroke mechanics.

[FooTheBar]

Sorry, if I wasn't accurate with the terminology. I was only referring to the seat travel that I want to measure for each stroke to check for consistency.

What do you think about the possibility to measure both seat and handle position to give the rower a better insight into his style?

[Citroen]

I think you're overthinking it and a minute and a half of video will tell you more than anything you're trying to artificially measure.

[FooTheBar]

But then we could also get rid of the force-plot and there would be no reason for the ErgData-App with the calculated stroke length if measured data is not important.

[Ombrax]

But then we could also get rid of the force-plot and there would be no reason for the ErgData-App with the calculated stroke length if measured data is not important.

Clearly some measurements are more important than others.

If you can come up with a fairly simple way to help you improve your erging technique then go for it - over the ages inventors toiling alone in their basement have given us lots of improvements.

Here's another idea: software that combines ErgData with real-time analysis of a side-view video of the user's rowing motion to highlight potential areas for improvement. (You make the software's job easier by sticking dots on critical points such as fixed points on the side of the rail, the user's knee, hip, elbow, shoulder, and the erg's handle. The software recognizes those locations and figures out what's happening and how "good" that motion is compared to an "ideal" technique.

[FooTheBar]

A custom made motion capturing system would be possible, but from my experience with commercial systems I know that they are rather hard to set up accurately. Repeatability is the main issue here as the user will have to put the markers on the same position on his body every time and they also must not move during the workout which is rather unrealistic. Markerless tracking (e.g. with a 3d camera) would be much involved and also depends on the clothing, so no simple system either.

My goal is a system that you can use without having to think about it just like the PM. Sensors for slide and handle position can be integrated into the erg so they looked like a good starting point. The erg could then generate three time series (force, slide position, handle position) that could first provide information with some manually implemented rules (e.g. no slide movement before large handle movement after finish). In a later version, some machine learning could also be applied to this data stream.

[hjs]

Rowing on the erg is no rocket science. To be good at it its talent first and lots of hard work second. After a while strokes are very simulair and you feel how it goes. The best ergers are otw people, and otw you have very little info, just you (boat) and the water. Focussing to much on all kind of numbers is for number geeks. Nice if you like that, but in the end there is only one number that really matters, pace per 500. And a good rower feels if he is going fast.

[jamesg]

The erg only gives rather limited information through the force curve which is rather hard to interpret and does not give hints on how to improve.

Suggest you watch the results, i.e. Watts and Rating. The erg is just basic engineering. You can then see immediately the effects of any variations to the machine (foot height, frontstop position, drag) and to style (sequences, postures). I'm happy enough to respect the standard values of all these and suspect that I'd only get any better by working longer and/or harder.

To get a baseline or benchmark stroke-work, based on height, calculate your ideal net stroke length L and a possible average handle force F. The product of these two is the Work in the stroke. Then discount the result for age and sex. The net value times Rating is Power in Watts.

Then compare with results. Any difference is likely due to non-standard practice.

For example, I'm 6'2" = 188 so consider L= 1.88/2= 0.94 and F = 1.88²*23/2 = 40.6 kg = 400 N.

So my work should = 0.94 * 400 = 375 Nm = 6.4 Watt minutes.

And it does usually. So I got myself off the hook of having to further adjust machine and style. Easy when you know how.

[Carl Watts]

Over the years I have found I need less data and analysis tools.

The basics you need are already on the Concept 2 monitor, have been since the PM1 back in like 1986, sure there has been additions like heartrate and force curves etc since the PM3 but wanting more than this is just fluff unless your an elite rower or at top competition level looking for that last 1%.

The gimmicks only go so far, the results or "Hints on how to improve" come from sweat and putting in the meters and at the end of the day its just a time or total meters, nobody really cares about your rating, technique or anything else about how you got there, just the final result.

[sander]

Hey!

I'm rowing at a local gym several times a week and since I'm a Maker/Hacker guy, I started to think how I could add some sensors to the erg to help be improve my technique.

The first thing that came to my mind was a sensor for the seat position. This could give me the length of each stroke so that I know if my strokes are constant or if I'm always at the same position at the catch.

The second interesting information would be the handle position (only the distance to the flywheel, not the vertical height) which I then could compare to the seat position. If I move the handle at the catch too long without moving the slide, I could visualize this to the rower so the he knows that his connection was weak. Similarly, at the beginning of the recovery, the handle should move a lot towards the front before the slide should start to move.

Has someone built something in this direction? The erg only gives rather limited information through the force curve which is rather hard to interpret and does not give hints on how to improve.

Yes, the Quiske pod and app: http://www.rowingperformance.com/

"Virtual Coach

Do you bum shove?

RowP App comes with a Virtual Coach for indoor rowing. The Virtual Coach gives immediate feedback on rowing rhythm and let's you know when you're doing it wrong by turning the corresponding tiles red.



Achieving perfect coordination is much easier when getting constant supervision of your technique. As a coach you can set the limits for right and wrong yourself, to align the technique of your crew during the winter months of indoor training."