SkiErg first impressions

Talk about the ski ergometer and training tool from Concept2
HornetMaX
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Re: SkiErg first impressions

Post by HornetMaX » January 16th, 2024, 6:07 pm

gvcormac wrote:
January 16th, 2024, 5:13 pm
Let's take the SkiErg out of the equation. If you do squats and/or hinges you will use energy raising your body, and that energy will be wasted as heat when you lower your body.
Not really. When you push yourself (or a weight) up, the work you do goes into potential energy for the weight you pushed up.
When you let the weight drop, the potential energy becomes kinetic energy (and you have to use your muscles if you want to prevent the weight hitting the floor). If the weight is tied to the wheel, its drop will lead to work done on the wheel, going into the Erg.
gvcormac wrote:
January 16th, 2024, 5:13 pm
Now pull on the SkiErg handles when lowering. Some of the energy that would otherwise be wasted will be transferred to the SkiErg. You can measure the amount by how much your apparent weight is decreased when you pull on the SkiErg. It gets a bit more complicated than that because work is force times distance, so you need to figure out how far up and down you are moving. But it would be a start.
Yes, but the SKiErg already measures this for you. Why would you want to measure it again and differently ?
gvcormac wrote:
January 16th, 2024, 5:13 pm
So long as your apparent weight is greater than zero (or maybe greater than the weight of the non-moving part of your body) you are wasting some of your lift. The goal is to minimize your apparent weight during the stroke, so as to maximize energy transfer to the machine.
The difference between your "apparent" weight and your usual weight (mass) is simply the force you're applying to the handles times gravity.
As said, the PM5 basically measures this already.
gvcormac wrote:
January 16th, 2024, 5:13 pm
The RowErg also involves waste energy, but its on the horizontal plane, so not as large -- just the kinetic energy you develop in recovery, not energy from lifting a heavy weight (you). If I recall correctly, studies have shown this waste to be between 10% and 20%.

The BikeErg has the least waste of all. A bit from the recipricating weight of one shin and 1/2 thigh at a time.
Quantifying waste (energy you spend that doesn't go into the Erg) is very difficult, but essentially you have friction (bearings etc), the bungee (for SkiErg and RowErg, due to hysteresis) and then all the energy you spend to accelerate/decelerate the different parts of your body.

Notice however than in the SkiErg case when you lift the heels and then hang from the handles, you let your weight do some work for you: the work done by your weight is essentially the work you have done when lifting the heels (lifting your weight). Waste is minimal for that and is likely more than compensated by the fact that you're offloading some work to your quads and calves instead of using only your arms.

Probably that's also why on-the-snow skiers also clearly bend the knees and hinge when double-poling: overall it's better.
1973, 5'8" (173cm), LW, started rowing Sep 2021 (after 10 years of being a couch potato), c2 log

RowErg PBs: Image

gvcormac
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Re: SkiErg first impressions

Post by gvcormac » January 16th, 2024, 6:21 pm

I will avoid detailed tit-for-tat.

When you elevate your mass, this indeed creates potential energy.

When you lower your mass, you dissipate this potential energy by heating your muscles. You don't convert any substantial fraction into useful work.

The SkiErg measures how much energy you impart to the flywheel. So I guess you have a point -- all you have to do is to figure out how much potential energy is dissipated when you hinge/squat without the BikeErg, and then figure out what fraction of that was actually transmitted to the flywheel. I posit that unless your apparent weight diminishes substantially (by the weight of the torso and 1/2 the thighs) you're wasting a lot of energy.

You can't really compare to real skiing, because in real skiing, the knee bend results in lifting and moving the leg, which has tiny mass compared to the body.

HornetMaX
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Re: SkiErg first impressions

Post by HornetMaX » January 16th, 2024, 7:19 pm

gvcormac wrote:
January 16th, 2024, 6:21 pm
I will avoid detailed tit-for-tat.

When you elevate your mass, this indeed creates potential energy.

When you lower your mass, you dissipate this potential energy by heating your muscles.
I think that's wrong (but the main point is below).
gvcormac wrote:
January 16th, 2024, 6:21 pm
You don't convert any substantial fraction into useful work.
If you're attached to a wheel/erg, yes you convert that potential energy into useful work. That's the idea of the whole lifting+hinge thing on the SkiErg.
So effectively, the work you do to lift yourself/hinge, goes into the Erg.

Easy way to check: start with heels up, arms fully extended perfectly vertical (let's imagine) and hands holding the skierg handles.
As soon as you drop your heels (no other movement), what happens to the wheel/erg ? It spins. Who does the work ? Gravity pulling your body down.
How much work ? The same amount you generated when you lifted your body up.
1973, 5'8" (173cm), LW, started rowing Sep 2021 (after 10 years of being a couch potato), c2 log

RowErg PBs: Image

gvcormac
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Re: SkiErg first impressions

Post by gvcormac » January 16th, 2024, 7:33 pm

You're not getting it. Of course, some of the potential energy is transferred to the flywheel. The question is, how much is tranferred to the flywheel, in proportion to how much is wasted in your muscles? You're missing the "in proportion" part.

HornetMaX
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Re: SkiErg first impressions

Post by HornetMaX » January 17th, 2024, 4:50 am

gvcormac wrote:
January 16th, 2024, 7:33 pm
You're not getting it. Of course, some of the potential energy is transferred to the flywheel. The question is, how much is tranferred to the flywheel, in proportion to how much is wasted in your muscles? You're missing the "in proportion" part.
That waste would occur anyway if you were to generate that work with another muscle ...

You seem to think that more stuff gets wasted ("dissipated by heating your muscles") when lifting & hinging but this seems very wrong to me.

Anyway, no big deal.
1973, 5'8" (173cm), LW, started rowing Sep 2021 (after 10 years of being a couch potato), c2 log

RowErg PBs: Image

gvcormac
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Re: SkiErg first impressions

Post by gvcormac » January 17th, 2024, 7:36 am

HornetMaX wrote:
January 17th, 2024, 4:50 am
gvcormac wrote:
January 16th, 2024, 7:33 pm
You're not getting it. Of course, some of the potential energy is transferred to the flywheel. The question is, how much is tranferred to the flywheel, in proportion to how much is wasted in your muscles? You're missing the "in proportion" part.
That waste would occur anyway if you were to generate that work with another muscle ...

You seem to think that more stuff gets wasted ("dissipated by heating your muscles") when lifting & hinging but this seems very wrong to me.

Anyway, no big deal.
Again, take the Erg out of it. Hinge and squat for a few minutes. Observer you increased heart rate and breathing. The potential energy from raising your center of gravity gets dissipated. Where do you think it goes? Your muscles aren't particularly elastic. There is no way more than a tiny fraction of the potential energy is reclaimed as "bounce" The key question is when you connect to the erg, how much of that energy is transmitted to the erg instead of being dissipated in the muscles.

I want to withdraw my concession on a point I made yesterday. You can't just measure energy to the flywheel, because some of that energy is generated actively by the hinge and arms during the stroke. So we really need to separate out what happens to the potential energy accumulated by standing.

HornetMaX
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Re: SkiErg first impressions

Post by HornetMaX » January 17th, 2024, 10:25 am

OK, let's take that discussion to private messages, I can try one last time to explain.

Back to the other discussion: today I tried single-poling.
i started a 10min workout with a couple of double-pole strokes, then switched to single-pole up to 5min and then to usual double-pole for the last 5min. What I noticed:
  • The PM5 didn't complain. The workout is here: https://log.concept2.com/profile/1528069/log/83600256
  • The entire session was a warm-up one, I do them keeping my HR below 140. I went way faster (2:24 vs 2:34 avg pace) with double poling, and that while having a very similar avg heart rate (136 vs 135 bpm). That despite the double-poling coming *after* the single-poling: in practice for the same pace my HR when double poling will be significantly lower than single poling at the same pace.
  • When single poling the stroke rate was obviously higher, but I also noticed that hinging with the torso was way less pronounced while bending the knees was more pronounced.
All this would need to be confirmed with a longer test (maybe this sunday I'll do 30min sp and 30min dp) and also with me getting a bit more accustomed to single poling. But yeah, first sight I'm not surprised essentially everybody on the SkiErg double-poles.
1973, 5'8" (173cm), LW, started rowing Sep 2021 (after 10 years of being a couch potato), c2 log

RowErg PBs: Image

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MudSweatAndYears
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Re: SkiErg first impressions

Post by MudSweatAndYears » February 4th, 2024, 4:22 pm

HornetMaX wrote:
October 2nd, 2023, 8:45 am
[*]I cannot reach the same level of power/pace I can do on the rower. Not by a mile (or two). Don't know if it's me (as in my technique sucks), or me (as in I'm all legs and that's OK on the RowErg but a tragedy on the SkiErg) or just me (as in I need more time to get better on the SkiErg).
I am using the RowErg for four years, and a BikeErg for two years. Three weeks ago I also got a SkiErg. My initial experience copies yours. I find that for all endurance efforts (say 7 minutes and longer) my RowErg power is typically 13-15% below my BikeErg power. But my SkiErg power is about half (!) my BikeErg power. This came as a shock, but even after the few weeks of training I had I do see my power levels on the SkiErg starting to creep up. Exciting to be back in this big-gains territory that I remember from the time I started on the RowErg.

I very much like the fact that the SkiErg provides a standing-up workout: no strapped in feet, no seat pain, just grab the two handles and there you go...
I run in the mud, I sweat on the erg, and I happily battle the years...
M 63, 1.80m/5'11", 75kg/165lb. Erging since Sept 2019.
https://erg-all-rounders.blogspot.com/p ... 22-23.html

Sakly
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Re: SkiErg first impressions

Post by Sakly » February 5th, 2024, 1:58 am

MudSweatAndYears wrote:
February 4th, 2024, 4:22 pm
HornetMaX wrote:
October 2nd, 2023, 8:45 am
[*]I cannot reach the same level of power/pace I can do on the rower. Not by a mile (or two). Don't know if it's me (as in my technique sucks), or me (as in I'm all legs and that's OK on the RowErg but a tragedy on the SkiErg) or just me (as in I need more time to get better on the SkiErg).
I am using the RowErg for four years, and a BikeErg for two years. Three weeks ago I also got a SkiErg. My initial experience copies yours. I find that for all endurance efforts (say 7 minutes and longer) my RowErg power is typically 13-15% below my BikeErg power. But my SkiErg power is about half (!) my BikeErg power. This came as a shock, but even after the few weeks of training I had I do see my power levels on the SkiErg starting to creep up. Exciting to be back in this big-gains territory that I remember from the time I started on the RowErg.

I very much like the fact that the SkiErg provides a standing-up workout: no strapped in feet, no seat pain, just grab the two handles and there you go...
I'm in the same "boat" 😄
Using the skierg of my gym for some weeks now, did ~59k on it until now. Only 15min blocks for warmup, covering ~3800m, no longer times/distances yet. During these warmups I typically go for a pace between 1:57 - 2:02, depending on the day. It feels much harder compared to the rower and my HR is about 20 beats higher at the same pace.
Did some 500m attempts recently, ~6s slower than on the rower.
Male - '80 - 82kg - 177cm - Start rowErg Jan 2022
1': 355m
4': 1217m
30'r20: 8068m
30': 8,283m
60': 16,222m
100m: 0:16.1
500m: 1:27.1
1k: 3:07.8
2k: 6:37.1
5k: 17:39.6
6k: 21:15.3
10k: 36:01.5
HM: 1:18:40.1
FM: 2:52:32.6
My log

bullitt0347
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Re: SkiErg first impressions

Post by bullitt0347 » May 10th, 2024, 9:49 am

So, my first impression are great, had a quick blast on the SkiErg after I set it up – which incidentally was a lot easier on my own than I thought it would be.
Going to have a longer session tonight. Really looking forward to having a go at the ergathlon – more than likely over the weekend.
My only gripe / whinge / moan would be the stand - £235 and the edges aren’t even smooth!! Don’t get me wrong, it's not splinter central but at least rub them down – Woodworking 101!!
Also, it would have been lovely to see the Concept logo on there as well.
I know trivia stuff, takes nothing away from the SkiErg itself, great build quality as you would expect. Brought my Rower back in 2006 and still going strong. I’m expecting the same from the BikeErg and now the SkiErg. Like most things you pay for what you get.

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