SkiErg Calorimetry

[flatbread]

How was the SkiErg calorimetry calibrated? Is it simply the same measurement from the rowing ergometer, or was it established by measuring the heat expenditure of subjects in the lab, and then defaulting to the 175lb man average, like the rower?

So, was the watt work output factored with the gross mechanical efficiency of the movement, and the energy cost of the recovery?

(I notice that calories expended on the bike and the rower are similar for HR, although the movements have very different GME -- a HR of 130 for instance, would put me at 1000cal/hr once my weight of 76kg is factored in, and on the bike, my powermeters give me 1000kj/hr at the same HR -- I know from lab tests that my GME is abour 25%, so for my cycling kj=calories. I notice that HR and the calories expended on the SkiErg are much lower than with the other two activities, which makes me ask about the process by which C2 established the calorimetry. For what it's worth, cal/hr for a given HR are the same on an elliptical at a local exercise lab, and they've validated that calibration -- so the SkiErg being the odd one out here has me wondering a bit.)

[flatbread]

No measure of calorimetry in this study, but as intensity increases, the lower body starts to do more of the work, and the more power you generate with the hips extending forward, and driving up with the legs, on the recovery, the more power you can then transfer into the hip hinge backwards and the drive down with the trunk as the arms follow.

When you go start to go hard, you're using more lower extremity than you think you are (note -- all these subjects were nordic skiiers, so they weren't using the machine like crossfitters).

https://pdfs.semanticscholar.org/b1f4/1 ... a40dbe.pdf

snip:

Abstract

Purpose. The present study examined the absolute behavior and the relative contributions to
poling power of 1) joint-specific powers and 2) total body power (Pbody, i.e. the rate of change
in total body mechanical energy) at increasing intensities while ergometer double poling.
Methods. Nine male elite skiers (body mass 81.7 ± 6.5 kg, height 1.86 ± 0.06 m) performed
three 4-min submaximal trials at low (LOW), moderate (MOD), and high (HIGH) intensity,
and one 3-min all-out peak test (MAX). All trials were performed standing on a force plate
and the ergometer was equipped with a force cell in order measure all external forces acting
on the body. Reflective markers were placed on anatomical landmarks. Kinetics and
kinematics were synchronized and recorded. By applying inverse dynamics, joint-specific
powers (elbow, shoulder, trunk, hip, knee and ankle) and Pbody was calculated for the poling
and retrieval phase, and for the complete cycle.

Results.

As net cycle poling power increased (116 ±16 W. 166 ± 36 W, 214 ± 38 W, and 306
± 38 W at LOW, MOD, HIGH, and MAX, respectively; all p < 0.05) the relative contribution
of the lower extremities increased from 39 ± 14 % at LOW to 65 ± 11 % at MAX (p < 0.05).
The relative contribution of the upper extremities was stable at ~28 ± 6 %. Pbody fluctuated
over the cycle, being generated during the retrieval phase (~100% of lower extremities
positive power) and partly transferred to poling power during the poling phase. More
specifically, Pbody was the main contributor to poling power (66 ± 13 % at LOW and 54 ± 7 %
at MAX). Overall, most power was produced by the body’s core, i.e. the hip, trunk, and
shoulder joints.

Conclusion.

The lower extremities generate an increasing amount of Pbody during the retrieval phase,
which was thereafter partly transferred to poling power during the poling phase. Enhancing
the lower extremities’ work as a way of increasing Pbody during the retrieval phase seems
crucial for optimal utilization of Pbody during poling phase.

[hjs]

No difference, the same pace on both ergs gives the same calories.

Purely based on feel I do think the skierg does burn a bit less.

And looking at the motion I also think it is less, on the rower most of the body does move, on the skierg the hips and less do bend a bit, but much less so. Its the upperbody and hands that move and need to be recovered, which is the part the Pm does not register.
The skierg does use a higher spm, but strokelenght is a good bit shorter and the higher people rate, the shorter the stroke gets.

[flatbread]

No difference, the same pace on both ergs gives the same calories.

Any idea how C2 determined this?

[hjs]

No difference, the same pace on both ergs gives the same calories.

Any idea how C2 determined this?

100% no. You can directly ask them, not here on the on the forum.
I guess its the most simple. Other point is also, its a bogus number to begin with, it very much depends on the rower and also on strokerate. So why bother? Whatever number it will always be a very rough reflexion of reality.

[Allan Olesen]

No difference, the same pace on both ergs gives the same calories.

Any idea how C2 determined this?

My guess would be rough guesswork. I can tell you how the calculation works on the RowErg:
Your measured energy on the erg is first divided by an assumed metabolic efficiency of exactly 25% to find the calories expended for this work. Then an additional 300 kcal/hour is added to account for energy usage not measured by the erg, mainly the work you do to move your own body instead of pulling the handle.

These two coefficients are so "round" that one could guess not much work went into establishing them.

[flatbread]

100% no. You can directly ask them, not here on the on the forum.
I guess its the most simple. Other point is also, its a bogus number to begin with, it very much depends on the rower and also on strokerate. So why bother? Whatever number it will always be a very rough reflexion of reality.

Why bother? Many users use the erg for weight management. Establish a measure based on proper technique*, that gives the user a reasonable figure that is within a few %.

You put some subjects in a calorimetry chamber, you look at the watts of work performed with the nordic technique (because it's meant as a training aid for that sport, so there is your intended baseline, although many users may choose to use different techniques), and then the heat expended. The relationship between work performed and heat expended tells you GME. Then you plot your slopes or curves for subjects, based on body mass, establish a middle point (such as the rower's 175lb man), and then use that value for calorimetry on the ergometer. A physiologist friend has done work with a few exercise machine (which are really just types of ergometers) companies to do such measurements.

It's not a bogus number -- it's a reasonable estimate based on intended use.

I will ask them.

* I understand you use a style that produces a higher erg score and is not the original intended technique of the machine; I hope you will allow the use of "proper" to refer to the technique the machine was originally designed for, with the concession that the understanding of "proper" may vary with the end user.

[hjs]

100% no. You can directly ask them, not here on the on the forum.
I guess its the most simple. Other point is also, its a bogus number to begin with, it very much depends on the rower and also on strokerate. So why bother? Whatever number it will always be a very rough reflexion of reality.

Why bother? Many users use the erg for weight management. Establish a measure based on proper technique*, that gives the user a reasonable figure that is within a few %.

You put some subjects in a calorimetry chamber, you look at the watts of work performed with the nordic technique (because it's meant as a training aid for that sport, so there is your intended baseline, although many users may choose to use different techniques), and then the heat expended. The relationship between work performed and heat expended tells you GME. Then you plot your slopes or curves for subjects, based on body mass, establish a middle point (such as the rower's 175lb man), and then use that value for calorimetry on the ergometer. A physiologist friend has done work with a few exercise machine (which are really just types of ergometers) companies to do such measurements.

It's not a bogus number -- it's a reasonable estimate based on intended use.

I will ask them.

* I understand you use a style that produces a higher erg score and is not the original intended technique of the machine; I hope you will allow the use of "proper" to refer to the technique the machine was originally designed for, with the concession that the understanding of "proper" may vary with the end user.

If the number is incorrect it has no meaning, it simply is wrong. That’s why I say, why bother, you will never know. For weight, watch the scale. Between two people the number can easily be off by 30/40%. Say a small female or large man.

The machine is ment to train fitness, nothing more nothing less, its has nothing to do with snow skiing. So the technique which gives the best scores, its “best”. Cause it uses the body the most efficient. Its very different from the rower where you very much can use the same stroke on water and machine.

You keep referring at my technique as wrong and crossfit, while you don’t have a clue what it looks like. I never been in a crossfit box in my life . Fine ofcourse, its a free world, but still a bit strange. You also don’t see me giving you critique on your style. On snow there is also not a single best technique, rating can also vary a lot. Cycling ditto, some guys use high gear, others much lighter. In both cases they could be fast.

The skierg is a vertical movement and snow skiing horizontal, not for nothing serious skiers are not often seen in the rankings, its not for them.

[flatbread]

The machine is ment to train fitness, nothing more nothing less, its has nothing to do with snow skiing. So the technique which gives the best scores, its “best”. Cause it uses the body the most efficient. Its very different from the rower where you very much can use the same stroke on water and machine.

To say it has nothing to do with snow skiing is an overgeneralization. As a former nordic skiier, I think the erg is a good training tool for the double polling motion (which was it's designed purpose). Of course it does not engage balance or the lower body as does actual skiing -- that's impossible on an indoor apparatus.

"Best" in this case depends on user purpose.

I am not bashing your style -- which you have given written description of, and which, from that description, one could generally refer to it as "crossfit" style, although you have not, as you have said, been a "crossfitter."

You're getting a little, um, ahead of your skis here.

[hjs]

The machine is ment to train fitness, nothing more nothing less, its has nothing to do with snow skiing. So the technique which gives the best scores, its “best”. Cause it uses the body the most efficient. Its very different from the rower where you very much can use the same stroke on water and machine.

To say it has nothing to do with snow skiing is an overgeneralization. As a former nordic skiier, I think the erg is a good training tool for the double polling motion (which was it's designed purpose). Of course it does not engage balance or the lower body as does actual skiing -- that's impossible on an indoor apparatus.

"Best" in this case depends on user purpose.

I am not bashing your style -- which you have given written description of, and which, from that description, one could generally refer to it as "crossfit" style, although you have not, as you have said, been a "crossfitter."

You're getting a little, um, ahead of your skis here.

https://m.youtube.com/watch?v=a3CppkvhoOM

Example of the dubble pool technique. Upperbody close to horizontal, hands below the knees at push off, in your words “crossfit” style?
I checked a clip of mine, I bend the knees more, the skierg does not allow to push back, back angle and hand end position is like the clip.

https://m.youtube.com/watch?v=bUlRz0oebvI

Racing clip, torso close to horizontal, hand at or below the knees. For all people in this clip.

[flatbread]

Ok, you win the internet today.

[hjs]

Ok, you win the internet today.

Do I get a price?

https://log.concept2.com/profile/921239

Arwed Egger, 183, lightweight rower, 56, former triathlete pulling solid times. Not a sprinter.

Strong rower, but his ski is not miles off, so he does not need “bulk” to get the pace down on the skier.
And no, I don’t know anything about his technique or style. He is German so maybe he does ski on snow. contact him?

[flatbread]

or how skiiers actually use the thing

https://www.youtube.com/watch?v=NAe9O2AM2YM

many videos from this club

(yes, you can get the back nearly horizontal and the hands below the knees for sprints, but not really the thing you want to do for the whole trail)

[hjs]

or how skiiers actually use the thing

https://www.youtube.com/watch?v=NAe9O2AM2YM

many videos from this club

(yes, you can get the back nearly horizontal and the hands below the knees for sprints, but not really the thing you want to do for the whole trail)

Really that guy can’t hold that for 1 minute. I showed you a long distance clip, not a sprint, You have now more or less lost every credit you had, everything you say is nonsens in this thread.

For those that want to see a sprint. 1500m upperbody stayes up, hands stays high.

https://m.youtube.com/watch?v=8vh-4uDdEio


Stop digging

Other clip https://m.youtube.com/watch?v=GprwjLmj3q0

From Norway, do best of the best. Those guys attack the snow.

[flatbread]

find someone who double poles so deeply that the back gets horizontal on every stroke. a few strokes, with coasting, yes.

and those norwegian guys have their hands at or slightly above the knees most of the time while double poling, not below.