Recording and comparing force data at different stroke rates

Maintenance, accessories, operation. Anything to do with making your erg work.
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oneillnick
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Joined: February 13th, 2024, 5:20 pm

Recording and comparing force data at different stroke rates

Post by oneillnick » February 13th, 2024, 5:50 pm

Hi, I am a very new rower so this question may be simple or misguided. Broadly, I am interested in seeing whether I can compare the individual force per stroke at different stroke rates.

When I use the ErgData app two of the available data fields are "ave force (N)" and "max force (N)". These are calculated per stroke correct? And when you download the data in a .csv from a workout from the logbook the data seems to be organized in a way so that each row is a single stroke. But there isn't any force data in the .csv, the data in the .csv file are Number, Time (seconds), Distance (meters), Pace (seconds), Watts, Cal/Hr, Stroke Rate, and Heart Rate. Looking around the forum I see people use SPI or stroke power index to estimate something similar to this by (Watts/Stroke Rate)? Just wanted to know A) whether there was any way to see the force data after a workout and B) is this something interesting to be looking at i.e. how much more/less force per stroke am I able to generate at 20 SPM vs 30 SPM

p_b82
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Re: Recording and comparing force data at different stroke rates

Post by p_b82 » February 14th, 2024, 5:23 am

Hi and Welcome,

They are values that are calculated on the fly and can be displayed in ergdata, but they are not metrics stored in the output.

However they are the basis for the power calculations, which are probably more use; because typically one "should" generate more power by increasing the stroke rate - as it's a measure of work done over time.

SPI is useful just to see the trend - do I massively drop off my work per stroke when I rate up, or can I maintain the same effort/technique at the higher rate, if the SPI number stays the same at the higher rates, then it's just fitness that we need to worry about etc.
M 6'4 born:'82
PB's
'23: 6k=25:23.5, HM=1:36:08.0, 30'=7,077m, 60'=13,702m
'24: 500m=1:37.7, 2k=7:44.80, 5k=20:42.9, 10k=42:13.1, FM=3:18:35.4
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JaapvanE
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Re: Recording and comparing force data at different stroke rates

Post by JaapvanE » February 14th, 2024, 8:02 am

oneillnick wrote:
February 13th, 2024, 5:50 pm
When I use the ErgData app two of the available data fields are "ave force (N)" and "max force (N)". These are calculated per stroke correct?
As far as we can tell, they are indeed calculated instantaneously.
oneillnick wrote:
February 13th, 2024, 5:50 pm
And when you download the data in a .csv from a workout from the logbook the data seems to be organized in a way so that each row is a single stroke. But there isn't any force data in the .csv, the data in the .csv file are Number, Time (seconds), Distance (meters), Pace (seconds), Watts, Cal/Hr, Stroke Rate, and Heart Rate.
It is communicated via the Bluetooth protocol, which can be read by ErgData but also by Painsled and similar tools. These other tools can record all stroke force data (including force curves).
p_b82 wrote:
February 14th, 2024, 5:23 am
However they are the basis for the power calculations,
Nope, they aren't. In a pure theoretical approach they might be used this way, but they can't due to limitations in the sensor setup.
p_b82 wrote:
February 14th, 2024, 5:23 am
typically one "should" generate more power by increasing the stroke rate - as it's a measure of work done over time.
This is correct. Or, as power and pace are directly linked, just look at the pace.

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