Convert C2 static erg to dynamic erg

[Charles Carroll]

I am curious. What do you think of this?

http://www.youtube.com/watch?v=wMKJtzuO088&feature=g-all-c&context=G2ff37bdFAAAAAAAADAA

[Jim Dwyer]

Been there, done that:
http://www.youtube.com/watch?v=0JCKl8d6MzQ&list=UUDZvlElEQq-6G4x6jENHHKQ&index=15&feature=plcp

I used a model B rail. A big guy would hits the ends but it works OK for
me.

Jim



"Charles Carroll" wrote in message news:9lf88j...@mid.individual.net...

[Stelph]

On Dec 22, 2:15 am, "Jim Dwyer" <jim.dw...@sympatico.ca> wrote:
> Been there, done that:http://www.youtube.com/watch?v=0JCKl8d6MzQ&list=UUDZvlElEQq-6G4x6jENH...

>
> I used a model B rail.  A big guy would hits the ends but it works OK for
> me.
>
> Jim
>

> "Charles Carroll"  wrote in messagenews:9lf88j...@mid.individual.net...

>
> I am curious. What do you think of this?
>

> http://www.youtube.com/watch?v=wMKJtzuO088&feature=g-all-c&context=G2...

Since the world record for the hour erg fell yesterday (Eric Murray
did 1:36.1) and it was done on a dynamic C2 rather than a static one,
Coudl you comment on how much of a difference to the Split it makes
now it is Drynamic as opposed to static? And the rates as I would also
expect you to be able to hold the rate higher as well

[Kit]

On Dec 21, 11:26 pm, "Charles Carroll" <charles_carr...@comcast.net>
wrote:

> I am curious. What do you think of this?
>

> http://www.youtube.com/watch?v=wMKJtzuO088&feature=g-all-c&context=G2...

The guy who built this posts on the RowingIllustrated forums as
1xsculler. If you PM him there, he'll send you design docs.

[Jim Dwyer]

That is what I did.
He was a great help but I did change things a bit from his design.

Jim


"Kit" wrote in message
news:2c7e9666-7b2b-4d9f...@p9g2000vbb.googlegroups.com...

[Tinus]

There has been some research which showed that the energy loss on a
static erg is not much significant. However this was done in the range
of 30 strokes per minute. At higher rates the efficiency of moving back
and forward decreases a lot more. This loss in efficiency is a lot less
on the dynamic C2 which allows the rower to waste hardly any energy on
the movement. It is very easy to achieve ratings above 60 per minute on
the dynamic C2 without much effort (if the drag factor is set correctly).

The C2 monitor determines distance based on the number of rotations and
the dragfactor. If you have a higher rate then much less energy is
required to be delivered to the flywheel for the same number of
rotations. The savings can be up to 10% in energy which means about 3
seconds for the time of Eric Murray.

[Zeebee]

On Dec 23, 3:07 am, Tinus <martijn.weteri...@wur.nl> wrote:
> There has been some research which showed that the energy loss on a
> static erg is not much significant. However this was done in the range
> of 30 strokes per minute. At higher rates the efficiency of moving back
> and forward decreases a lot more. This loss in efficiency is a lot less
> on the dynamic C2 which allows the rower to waste hardly any energy on
> the movement. It is very easy to achieve ratings above 60 per minute on
> the dynamic C2 without much effort (if the drag factor is set correctly).

Dr. Valery Kleshnyev calculated energy needed for moving the body back
and forth on a stationary erg at the level of 60 to 80 watt.
That is quite a lot. That would be up to 1/4 or 1/5 of energy
generated during the average rowing test. Right?
So why people do not make so much better times on a Dynamic erg?
(Actually, most people say their times on Dynamic are worse.)

Yes, it is easier to achieve high ratings on a Dynamic compared to
static erg. However, it applies only to very short pieces and
extremely high ratings.
My own experiments with the 60 seconds max out test , rowed at rating
over 50 showed advantage of 5 to 10 watt for Dynamic. So, where is the
rest of 80 watt gone?

During another test, 4 series of 500m runs made on three machines side
by side: static, on slides and dynamic (altogether 12 timed pieces)
made with the same perceived effort, showed no difference in times and
the ratings on slides and on dynamic were identical and *lower* than
ratings on a stationary. Again, where's the advantage of "easier
rating" gone, and where's the advantage of power not being wasted
gone?
I wrote about this test in this thread:
http://groups.google.com/group/rec.sport.rowing/browse_thread/thread/669c500db6bdef20/48085848d0ce6247?lnk=gst&q=Let%27s+go+Dynamic#48085848d0ce6247

I find rowing on the Dynamic almost identical to rowing on the C2 on
slides. And Slides are available for quite a few years now and there
is a quite a lot of data available on the topic. Again, why people
don't make better times on slides?

--
Yours Virtually, Zibi

[Tink]

For those interested in the Eric Murray comment:
http://tvnz.co.nz/othersports-news/rowers-break-records-off-water-video-4667333

[Tinus]

The energy needed to move back and forward is not necessarily the energy
lost. Some energy needed to move back and forward can be converted into
muscle energy. The true energy needed to move back and forward has to be
determined experimentally using biomechanical measurements of the
rower's power output.

Your own experiments showed a 5/10 watt advantage. So yes the 60/80 watt
is not true but there still is a difference. By arguing against
Kleshnev's numbers specifically you don't argue against the idea in general.

Why people don't make better times on the dynamic I don't know. It may
depend on moderator variables. Rating higher for instance is mostly
beneficial while keeping the ratio drive:recovery constant. Many other
examples can be named why people don't achieve the theoretical improvement.

At least this new record is an example. Can he do it on a static machine?

[Zeebee]

On Dec 26, 4:09 pm, Tinus <martijn.weteri...@wur.nl> wrote:
> The energy needed to move back and forward is not necessarily the energy
> lost.

Agree! Absolutely! :-)
I believe that these calculations are rather conservative, it is
probably even more. I remember seeing a figure 130 watt somewhere. It
really depends on a rower, on cadence rate, his rowing style and size
-- the taller and heavier a rower, the more energy is needed to change
the direction of his movement. And i am pretty sure that not all of
this energy is lost.
(On stationary erg) Around the catch one has to slow down the forward
movement, change its direction and accelerate. That takes a lot of
effort, especially from legs. By accelerating ones body rower loads it
with some kinetic energy. And at the end of the stroke, this energy
can be retained and directed into a handle.

> Your own experiments showed a 5/10 watt advantage. So yes the 60/80 watt
> is not true but there still is a difference. By arguing against
> Kleshnev's numbers specifically you don't argue against the idea in general.

I'd say like this:
on the stationary erg amount of energy needed for moving the body
back and forth is quite significant, but some of this energy goes back
into the oar handle. The actual energy loss is only a portion of
that.

> Why people don't make better times on the dynamic I don't know.

Three years ago i moved to rowing on slides, a year ago i've got my
own C2 Dynamic. I try to avoid rowing on a stationary erg but
sometimes i do, in my rowing club or in the gym. Now i think i have a
pretty good feeling what the difference is, i only struggle with
putting this into words.

I see it like this:
On a Dynamic, or on slides, we avoid accelerating the body back and
forth and energy loss but at the same time rowing on a Dynamic is more
difficult. (As much as rowing on water is different from rowing on a
stationary erg.) In another words, rowing on a stationary brings some
energy loss but at the same it is easier to apply power.

It is easier to observe around the catch.
Rowers body moving forward has to be slowed down, and this begins even
before the drive phase begins. Then body movement changes direction ,
then the body accelerates. See, the effort is spread over a period of
time. (This is why *timing* of the catch on a stationary is screwed.)
This allows the rower to "pre-load" the stroke before it begins.
Moreover, the leg power around the catch works against the center of
gravity, which is pretty low in a body. It is almost like working out
on a leg press in a gym.

Contrary, on the Dynamic, (like in real rowing) the drive phase begins
suddenly, in an instant. And all the power has to be transmitted from
the stretcher to the oar handle. The whole body works like a
connection, or a "bridge". (Rowers center of mass is not moving so
there's no working against it, which would be easier.) This puts more
strain on the core muscles. It requires the whole body, especially
core and trunk muscles to be trained for it, and it makes breathing
more difficult.

What happens during the finish of the drive phase is more subtle. I
think i could feel it intuitively quite early but i couldn't name it
until i've overheard one very experienced rower, once world champion,
giving instructions to his trainee before the erg test, he explained
to him how to "cheat" on the erg in order to get a better score. He
advised a strong "jerking" of the handle at the end, so much that the
movement of the body reverses. Again, this effort of the arms is
between the oar handle and the center of mass and it can be stretched
in time even into beginning of recovery.
Contrary, on the Dynamic, one has to provide the unbroken connection
or the "bridge" right to the very end of the drive phase, through the
trunk or core muscles. And once the drive phase is finished, then it's
finished.

>
> At least this new record is an example. Can he do it on a static machine?

Concerning the effort, or power needed -- i believe yes, "easily". (As
much as rowing with 394 watt power output for 60 minutes can be
easy.)
But i don't think he would like to go back to the stationary -- unless
making new world records would become his goal in and out of itself.
He is preparing for rowing on water, for London 2012.
I am pretty sure that Eric Murray made his record on the Dynamic not
because it is easier -- i believe it is not -- but because this is his
primary tool for training, something he is already used to. And he
announced breaking the record beforehand, so he was confident enough
that he would do it even on the Dynamic.

--
Virtually Yours, Zibi

[Kit]

On Dec 27, 3:36 pm, Zeebee <zbychobikeri...@gmail.com> wrote:

> (On stationary erg) Around the catch one has to slow down the forward
> movement, change its direction and accelerate. That takes a lot of
> effort, especially from legs. By accelerating ones body rower loads it
> with some kinetic energy. And at the end of the stroke, this energy
> can be retained and directed into a handle.
>

> Virtually Yours, Zibi

I believe that this is mitigated to some extent by the extra
compression in the knees when your body weight moves into the catch on
a static erg. This adds extra spring to the start of the leg drive and
extra length to the stroke. There is the question of whether this is a
good thing from a technical point of view, but in terms of energy
loss, it may not be as great as you imply.IMHO

[Tinus]

On 12/27/2011 04:36 PM, Zeebee wrote:
> On Dec 26, 4:09 pm, Tinus<martijn.weteri...@wur.nl> wrote:
>> The energy needed to move back and forward is not necessarily the energy
>> lost.
>
> Agree! Absolutely! :-)
> I believe that these calculations are rather conservative, it is
> probably even more. I remember seeing a figure 130 watt somewhere. It
> really depends on a rower, on cadence rate, his rowing style and size
> -- the taller and heavier a rower, the more energy is needed to change
> the direction of his movement. And i am pretty sure that not all of
> this energy is lost.
> (On stationary erg) Around the catch one has to slow down the forward
> movement, change its direction and accelerate. That takes a lot of
> effort, especially from legs. By accelerating ones body rower loads it
> with some kinetic energy. And at the end of the stroke, this energy
> can be retained and directed into a handle.
>

The slowing down around the catch actually does not take effort in the
sense of energy expenditure. Work on the rower is negative! Energy is
stored in the leg muscle and tendons. (compare with the effort of a
spring in a pogo stick)

>> Your own experiments showed a 5/10 watt advantage. So yes the 60/80 watt
>> is not true but there still is a difference. By arguing against
>> Kleshnev's numbers specifically you don't argue against the idea in general.
>
> I'd say like this:
> on the stationary erg amount of energy needed for moving the body
> back and forth is quite significant, but some of this energy goes back
> into the oar handle. The actual energy loss is only a portion of
> that.
>

So besides energy going back into the handle (which should optimally be
be close to 100%) there is also energy going back into the legs. The
portion lost is only very small.

>> Why people don't make better times on the dynamic I don't know.
>
> Three years ago i moved to rowing on slides, a year ago i've got my
> own C2 Dynamic. I try to avoid rowing on a stationary erg but
> sometimes i do, in my rowing club or in the gym. Now i think i have a
> pretty good feeling what the difference is, i only struggle with
> putting this into words.
>
> I see it like this:
> On a Dynamic, or on slides, we avoid accelerating the body back and
> forth and energy loss but at the same time rowing on a Dynamic is more
> difficult. (As much as rowing on water is different from rowing on a
> stationary erg.) In another words, rowing on a stationary brings some
> energy loss but at the same it is easier to apply power.

Are you talking about dynamic ergs in general or the C2dynamic
specifically? This machine is an exception and very easy to row on. The
seat movement has a strong dampener and you are sitting very tight on a
single spot. You can make almost any type of wrong movement without
getting bad feedback. I know several novice rowers (few months
experience) who have tried this machine without much troubles.

[Charles Carroll]

> > On a Dynamic, or on slides, we avoid accelerating the body back
> > and
> > forth and energy loss but at the same time rowing on a Dynamic is
> > more
> > difficult. (As much as rowing on water is different from rowing on
> > a
> > stationary erg.) In another words, rowing on a stationary brings
> > some
> > energy loss but at the same it is easier to apply power.
>
> Are you talking about dynamic ergs in general or the C2dynamic
> specifically? This machine is an exception and very easy to row on.
> The
> seat movement has a strong dampener and you are sitting very tight
> on a
> single spot. You can make almost any type of wrong movement without
> getting bad feedback. I know several novice rowers (few months
> experience) who have tried this machine without much troubles.

Tinus,

Just to be unmistakably, by “the C2dynamic” do you mean the below?

http://www.concept2.com/us/indoorrowers/dynamic_home.asp

It is my experience that the C2 on slides with a CorePerform seat
initially gives everyone trouble, even experienced on-water scullers.
It just insists that you apply power evenly with both feet when you
push off the stretcher. Being just the tiniest bit sloppy puts the
"wobbly" in wobbly seat.

But I cannot say anything about Concept 2’s new Dynamic Indoor Rower.
I have never had the opportunity to use one.

Cordially,

Charles

[Tinus]

Yes, that one. It is just the leg/hip and arm movement. No wobbly seat
and the dynamics of the kinetic energy in the body-erg system is
practically absent. This means a very large freedom in the type/style of
movement.

[Carl]

Some research shows low energy loss while other work shows relatively
large losses.

On a fixed erg you have to accelerate your body mass from stationary at
the finish, with zero contribution to the work done in spinning the
flywheel. This is an irrecoverable energy loss which can be easily
calculated

Then you have to decelerate back down to zero velocity before the next
catch. We see 2 way in which this is done: the "slam" technique and the
"apply load to the stretcher" method. If you slam into front-stops you
may achieve something of a recoil effect which will bounce you back up
the slide, but only at the cost of significant stresses to parts of the
knee joint (which may come back to haunt you later). Otherwise, you
will do significant work (an amount not much different from that done to
get you moving from backstops) to make that more sensible deceleration.
This difference in individual technique could account for up to ~50%
differences between individuals in the excess energy requirement on the
static erg.

Rating increase, by increasing the acceleration required for each
recovery (since the lion's share of any rating rise comes from speeding
up the recovery), must progressively increase the proportion of the
static erg's energy dissipation,

Note that neither the slam, nor the deceleration approach to front-stops
is remotely similar to what you do in the boat - where it is the boat
which oscillates beneath you, not you oscillating above the boat. And
that's the other area where the dynamic erg benefits the rower who
aspires to row well (& reduce injury).

As to your last paragraph:
It is far from clear what you are trying to say. If the time-averaged
power delivered to the flywheel remains the same, then indeed you will
do less work per stroke, but this should not affect the monitor reading
since you'll do the same work per unit time. AIUI, erg monitors know
the rotational moment of inertia of the flywheel, carry an inbuilt
algorithm for power dissipation rate versus angular velocity &
repeatedly recalculate the aerodynamic drag factor for the flywheel from
its deceleration characteristics as measured during each recovery. They
should be completely unaffected by rate.

Of course, the aerodynamic characteristics of some erg fans & their
housings do significantly skew the monitor outputs. Thus
aerodynamically well-designed & quiet-running multi-bladed fans have
anything but the expected v-squared drag relationship because they have
very definite sweet spots of throughput vs speed. In contrast, much
cruder fans which work more as egg-beaters will work much closer to the
desired drag characteristics across their operating range. Again,
intake characteristics (and some intakes are distinctly odd from an
aerodynamic perspective) can strongly affect the air flows in a
time-dependent fashion - which can result in technique dependent
readings being delivered by the monitor.

Cheers -
Carl

--
Carl Douglas Racing Shells -
Fine Small-Boats/AeRoWing Low-drag Riggers/Advanced Accessories
Write: Harris Boatyard, Laleham Reach, Chertsey KT16 8RP, UK
Find: http://tinyurl.com/2tqujf
Email: ca...@carldouglas.co.uk Tel: +44(0)1932-570946 Fax: -563682
URLs: www.carldouglas.co.uk (boats) & www.aerowing.co.uk (riggers)

[Tinus]

On 12/29/2011 04:04 PM, Carl wrote:
> On a fixed erg you have to accelerate your body mass from stationary at
> the finish, with zero contribution to the work done in spinning the
> flywheel. This is an irrecoverable energy loss which can be easily
> calculated

You are right that this work can be calculated easily but I wouldn't
agree that it is irrecoverable.

>
> Then you have to decelerate back down to zero velocity before the next
> catch. We see 2 way in which this is done: the "slam" technique and the
> "apply load to the stretcher" method. If you slam into front-stops you
> may achieve something of a recoil effect which will bounce you back up
> the slide, but only at the cost of significant stresses to parts of the
> knee joint (which may come back to haunt you later). Otherwise, you will
> do significant work (an amount not much different from that done to get
> you moving from backstops) to make that more sensible deceleration. This
> difference in individual technique could account for up to ~50%
> differences between individuals in the excess energy requirement on the
> static erg.
>

The deceleration before the catch is performed by eccentric muscle
contraction. You don't do work in an eccentric muscle contraction.

> As to your last paragraph:
> It is far from clear what you are trying to say. If the time-averaged
> power delivered to the flywheel remains the same, then indeed you will
> do less work per stroke, but this should not affect the monitor reading
> since you'll do the same work per unit time. AIUI, erg monitors know the
> rotational moment of inertia of the flywheel, carry an inbuilt algorithm
> for power dissipation rate versus angular velocity & repeatedly
> recalculate the aerodynamic drag factor for the flywheel from its
> deceleration characteristics as measured during each recovery. They
> should be completely unaffected by rate.

The relation for power dissipation rate versus angular velocity is
indeed unaffected by rate. However, the average power dissipation rate
versus average velocity is not unaffected by rate.

Erg monitors don't take that into account (and they shouldn't because it
is much like rowing on water, if you have high velocity variations more
power is required for the same average velocity). It means that a better
result can be achieved on a machine which has less negative effects for
high ratings. The concept dynamic is such a machine.

[Charles Carroll]

Tinus,

So Concept 2’s new Dynamic Indoor Rower provides a very large freedom
of movement!

That’s a disappointment. I had hoped it would be more demanding.

Have you ever used a wobbly seat with the Dynamic Indoor Rower (DIR)?
My guess is that the wobbly seat would make the DIR more demanding.
But I wouldn’t know how to gauge the significance.

Ergs definitely have a role in training and you can learn a lot from
using one. But even so, given the opportunity to be out on the water,
I would never stay in a boathouse and erg.

Warmest regards,

Charles

[Charles Carroll]

Tinus,

By the way, I found this video link last night. Isn’t it a video of
RSR’s own Stelph in a Rowperfect Session? Take a look at Stelph’s
force curve. Is he pulling perfect parabolas?

http://www.youtube.com/watch?v=8zjN1emlpzc&feature=BFa&list=HL1325184718&lf=mh_lolz

Cordially,

Charles

[Zeebee]

On Dec 29, 7:48 pm, "Charles Carroll" <charles_carr...@comcast.net>
wrote:

> Tinus,
>
> So Concept 2’s new Dynamic Indoor Rower provides a very large freedom
> of movement!

What's wrong with that? Would you prefer a rowing machine that
literally *forces* certain moving patterns onto a rower?

> That’s a disappointment. I had hoped it would be more demanding.

Oh, Charles, i sense some misunderstanding here. Something's probably
"lost in translation". :-)

There are big forces of inertia when rowing on the stationary erg. The
whole body of a rower is moving back and forth -- rower's center of
gravity deceleraties, changes direction, accelerates again, all this
induces significant inertia forces. And these forces kind of "mask"
own movements of the rower.

My wife who has a pretty good feeling for the boat, when confronted
with Indoor Rower would say: "I can't stand how this machine *trows*
me back and forth". She decided that it has not much to do with a
real rowing and never bothered to practice on one. Only when we've got
C2 Dynamic, she started some serious training on it. And this resulted
in a gold medal at World Masters this year. (You see, we can't row/
scull on water for half a year, so winter without ergometer means
winter without any rowing at all.) I'm not saying that C2 Dynamic is
so much better that she's got gold because of it. I mean it so much
better that she bothered to use it at all.

Yes, C2 Dynamic provides larger freedom of movement -- because the
artificial inertia forces are absent. Nothing is forcing one to move
in this or that way. You just sit and do what you feel like. Like on a
real boat. What else would you want?

When i've got my Dynamic year ago, first i took it for a week to my
club for testing, to compare it side by side with ordinary erg. We
have few experienced rower in this club and they all said this machine
is more demanding. The'd say: it requires more careful coordination,
or makes the faults more visible. Many inexperienced rowers who tried
Dynamic wouldn't like it, they would say it is difficult, or "weird"
-- suddenly it was kind of difficult to row properly and smooth,
especially at low cadence.
For example in my case, my biggest problem is that i open my body too
early. On the Dynamic it became much more visible. Now i really have
to work on this!

> Have you ever used a wobbly seat with the Dynamic Indoor Rower (DIR)?

I've got my Core Perform mounted. It wasn't straightforward, cause the
original seat is pretty low, moves just millimeters over the fan
housing, but some simple spacers would do the trick.

> My guess is that the wobbly seat would make the DIR more demanding.
> But I wouldn’t know how to gauge the significance.

Exactly as difficult as Core Perfom mounted on a normal erg. Tricky.
Balancing the Core Perform is not exactly the same like balancing a
single sculler but anyway it forces one to "sit lightly".
Last winter was my first with Core Perform. And in the spring, during
first outing on a single after nearly 7 months months of winter pause,
for a first time ever i didn't have a "Bambi on ice" feeling (This is
expression i've learned from Olaf Tufte, apparently even he
experiences it sometimes.) My first outing on a single this year felt
exactly like the last one last one year before. I am yet to see how
it's going to be the next springtime.

> Ergs definitely have a role in training and you can learn a lot from
> using one. But even so, given the opportunity to be out on the water,
> I would never stay in a boathouse and erg.

I know, I know, people in a Bay Area tend to complain about the
weather, that it is cold sometimes. But Charles, please do not forget
how lucky bastards you are! Cold current around Alcatraz island? Yeah,
come to the fjords! The are places where rowers simply can not row on
water sometimes. Even when it is not frozen, it is simply too
dangerous.

--
Virtually Yours, Zibi

[Stelph]

On Dec 29, 6:59 pm, "Charles Carroll" <charles_carr...@comcast.net>
wrote:

> Tinus,
>
> By the way, I found this video link last night. Isn’t it a video of
> RSR’s own Stelph in a Rowperfect Session? Take a look at Stelph’s
> force curve. Is he pulling perfect parabolas?
>

> http://www.youtube.com/watch?v=8zjN1emlpzc&feature=BFa&list=HL1325184...
>
> Cordially,
>
> Charles

Yup thats me, I filmed this just after I managed to get my hands on a
second hand rowperfect and when I tried out the Remote Coaching
service that Rowperfect now offer:

http://www.rowperfect.co.uk/shop/remote-coaching-service-244.html

Youve reminded me that I need to record another session as well to see
how ive come on (or not :-p) from using the RP!

[Carl]

Charles, I think you will find that they are not "perfect parabolas".
Nor, might I respectfully suggest, is that any good reason (on grounds
of boat propulsion) why they should be.

What I see in Thomas's force profile is:
1. A good, rapid rise in force at the catch. I think he feels a quick
connection on the machine?
2. A relatively higher middle - I'd have preferred the early
straight-line rise of the catch to continue higher at the same ramp
rate/gradient, to be followed by a flatter middle, giving a
redistribution of effort from the middle towards the tail end of the catch.
3. A well-sustained finish - despite the fact that the force curve is
always likely to fade away slower than the catch rises.

In all, pretty good. And that fits with what we know of this particular
sculler's racing results.

[Carl]

On 29/12/2011 16:11, Tinus wrote:
> On 12/29/2011 04:04 PM, Carl wrote:
>> On a fixed erg you have to accelerate your body mass from stationary at
>> the finish, with zero contribution to the work done in spinning the
>> flywheel. This is an irrecoverable energy loss which can be easily
>> calculated
>
> You are right that this work can be calculated easily but I wouldn't
> agree that it is irrecoverable.
>
>>
>> Then you have to decelerate back down to zero velocity before the next
>> catch. We see 2 way in which this is done: the "slam" technique and the
>> "apply load to the stretcher" method. If you slam into front-stops you
>> may achieve something of a recoil effect which will bounce you back up
>> the slide, but only at the cost of significant stresses to parts of the
>> knee joint (which may come back to haunt you later). Otherwise, you will
>> do significant work (an amount not much different from that done to get
>> you moving from backstops) to make that more sensible deceleration. This
>> difference in individual technique could account for up to ~50%
>> differences between individuals in the excess energy requirement on the
>> static erg.
>>
>
> The deceleration before the catch is performed by eccentric muscle
> contraction. You don't do work in an eccentric muscle contraction.
>

Your statement above is not entirely true. You may, with appropriate
training, be able during recoil to recover a part of the energy absorbed
in the eccentric contraction (= extension under load) occurring when
clumsy users slam into the stretcher. However, you will not recover all
of it (the kangaroo is much better at this). You may also damage the
muscles &, perhaps worse, by their uncontrolled over-extension, do
lasting damage to the structure of the knee joint.

Such an action, although it can also be used to strengthen the affected
muscles, has otherwise no direct relevance to the normal rowing action.
So I'd prefer the rower on a fixed erg to actively decelerate onto
front-stops, which will consume energy.

The difference between active deceleration & effectively uncontrolled
eccentric contraction may indeed account for the variability of reported
energy wastage on fixed ergs compared to dynamic ergs.

>> As to your last paragraph:
>> It is far from clear what you are trying to say. If the time-averaged
>> power delivered to the flywheel remains the same, then indeed you will
>> do less work per stroke, but this should not affect the monitor reading
>> since you'll do the same work per unit time. AIUI, erg monitors know the
>> rotational moment of inertia of the flywheel, carry an inbuilt algorithm
>> for power dissipation rate versus angular velocity & repeatedly
>> recalculate the aerodynamic drag factor for the flywheel from its
>> deceleration characteristics as measured during each recovery. They
>> should be completely unaffected by rate.
>
> The relation for power dissipation rate versus angular velocity is
> indeed unaffected by rate. However, the average power dissipation rate
> versus average velocity is not unaffected by rate.
>
> Erg monitors don't take that into account (and they shouldn't because it
> is much like rowing on water, if you have high velocity variations more
> power is required for the same average velocity). It means that a better
> result can be achieved on a machine which has less negative effects for
> high ratings. The concept dynamic is such a machine.

Which is, in another form, the same argument I'd advance for reducing
the time-average root mean square value of the fluctuating boat velocity
when rowing.

[Tinus]

On 12/31/2011 06:25 PM, Carl wrote:
>
> Such an action, although it can also be used to strengthen the affected
> muscles, has otherwise no direct relevance to the normal rowing action.
> So I'd prefer the rower on a fixed erg to actively decelerate onto
> front-stops, which will consume energy.
>

But it must be mentioned that the energy consumed is not work done by
the muscles but only loss of the kinetic energy. Also, during active
deceleration some energy is still recovered. You can compare this to the
tests in which you have to jump from standstill. If you want to use the
energy from an eccentric muscle contraction prior to concentric muscle
contraction then you don't want to slam but instead you do it
controlled. Basketball players making a free throw show the ideal
speed/acceleration of this plyometric movement. It is close to the catch
of rowers which don't slam. I even believe that a lot energy in the slam
is lost because it happens without controlled contraction causing a
delay of the subsequent concentric contraction which increases the
degree of hysteresis.

[Carl]

From the above I think we are agreed that, on a fixed erg, a not
insignificant amount of energy (kinetic energy) is dissipated in
bringing the body to a halt before the catch? And we may also agree
that not all of the KE is thus dissipated? But this gives us no measure
of how much is recoverable, except that it is probably non-zero &
definitely a good way less than 100% - the actual proportion being very
dependent on the individual erg user.

I'd expect habitual fixed erg users, through longer practice & the
adoption of what would be poor in-boat technique at the catch to be able
to achieve a higher energy recovery through eccentric contraction at the
catch than regular users of dynamic ergs and competent scullers who do
not make much use of fixed ergs.

This, in turn, may help to explain the wide differences in values of
this dissipation by different researchers.

However:
Actual rowing, as opposed to the fixed erg, cannot recover energy within
the leg muscles around the catch since in rowing there is no meaningful
deceleration of the rower's body preceding the catch. But too few
rowers seem to realise how poorly the fixed erg simulates the rowing
catch, and too many rowers row as if the in-boat catch involves being
compressed by application of a decelerating force against the stretcher!

Happy New Year to all!

[Charles Carroll]

> Would you prefer a rowing machine that
> literally *forces* certain moving patterns onto a rower?

Zibi,

It seems to me that the answer to this question can be found in another
question: Why are some people with hugely impressive erg scores such poor
boat movers?

If I tried to do in my shell the things I can do on a static erg, I would
capsize before I could blink my eyes. So yes, I would prefer a rowing
machine that forces me to move the way I would have to move in my shell.
After all, isn’t the erg intended to be an off-water training device for
on-water rowers? Hence my slides and CorePerform seat, etc!

I am, however, very glad to learn that you and your wife have had such
promising experiences with C2’s new Dynamic Indoor Rower. You experiences
with this erg appear to be markedly different from Tinus’s. Could it be
that the CorePerform seat which you attached to your erg accounts for this
difference?

I am very eager to try the new Dynamic Indoor Rower for myself. Marin
Rowing has a couple of these ergs, and that Club is about a twelve minute
drive up the Freeway from Sausalito. The trouble is that every time I think
about driving up to the Marin Club I also think about all the on-water time
I will be missing in Sausalito. Maybe one morning when the weather is
really horrible I will drive up to Marin.

Congratulations to your wife on her gold medal at the World Masters. I
suspect that training during the winter months on your new erg was at least
partially responsible for this.

Do you subscribe to Rebecca’s newsletter from Rowperfect.co.uk? The latest
newsletter arrived in my mailbox just this morning. In it Xeno Muller has
an article titled “My Coach: Harry Mahon.” Xeno writes:

“I have several memorable experiences with Harry regarding sculling
technique. He reminded me constantly that him pulling 1:47 at stroke rate
20, with his body size is only the result of hanging from the leg drive and
connecting with the upper body without pulling. He would watch like a hawk
for any contraction in the upper body that came prematurely during the leg
drive. While he coached us on the rowing machine, he would stand next to
me and mimic relaxed shoulders with hands drawn to the side of the ribcage,
with a totally relaxed face, and say, that the stroke is executed in a
powerful relaxed way. Harry loved the Rowperfect and knew how difficult it
was to teach pushing and hanging on a static rowing machine. Harry’s
ability to understand, push and hang, without ever having been a record
smashing rower himself is really remarkable. He simply had a great
understanding of body mechanics and the Eye.”

So Harry Mahon had his scullers and rowers training on Rowperfects!

This suggests to me that Harry Mahon appreciated the benefits of dynamic
ergs. I myself do not do a lot of training on an erg only because (knock on
wood) I am able to scull most of the time. But I have done some training on
an erg, and I am certainly not one of those people who despise ergs.
Indeed, I have found and am continuing to find that if you use an erg
correctly you can achieve amazing results. Not only can you acquire all the
physiological benefits that come from erging, but you can also really
polish technique. You just have to go slow and be patient.

All the best,

Charles

Ps. Sandy and I have plans to be in Rome in May. I asked a friend how long
the train trip is from Rome to Oslo. He said he thought two to three days.
Yikes! We’d never make it. Maybe some other summer.

[Charles Carroll]

Zibi,

I forgot. I have a question for you, or Tinus, or Carl, or anyone else who
cares to answer it.

Do you know of anyone who has an immensely impressive time on a Rowperfect
who is a poor boat mover?

Charles

[Justus]

I'll jump in under the "anyone else" category :-)

Rowperfect Australia has organised an indoor Rowperfect championship with
rowers as well as non-rowers a few years in a row. If I recall correctly,
the best time achieved in the mens masters in 2007 was pulled by Peter
Hardcastle, someone who used the Rowperfect at the gym only and had no
on-water mileage.

(this is from a memory of a telephone call almost 5 years ago; I do hope I
got the facts right)

Justus

[Charles Carroll]

> Do you know of anyone who has an immensely impressive time on a
> Rowperfect who is a poor boat mover?

Justus,

Wouldn't it be interesting to know if Peter Hardcastle ever got on water? I
would love to hear Mr. Hardcastle's first impressions of trying to move a
boat. Would he say that the Rowperfect was a help? And if f so, would he be
able to describe how it helped?

Happy New Year,

Charles

[Stelph]

On Jan 5, 6:08 pm, "Charles Carroll" <charles_carr...@comcast.net>
wrote:

> > Do you know of anyone who has an immensely impressive time on a
> > Rowperfect who is a poor boat mover?
>
> Justus,
>
> Wouldn't it be interesting to know if Peter Hardcastle ever got on water?

Is this the same Peter Hardcastle who's an Olympic rower?

http://www.rowingone.com/n_bio_rower.fwx?no_id=4402

[Charles Carroll]

> Is this the same Peter Hardcastle who's an Olympic rower?
>
> http://www.rowingone.com/n_bio_rower.fwx?no_id=4402

Stelph,

Justus writes: “If I recall correctly, the best time achieved in the mens

masters in 2007 was pulled by Peter Hardcastle, someone who used the

Rowperfect at the gym only and had no on-water mileage.”

The Peter Hardcastle in your link started rowing in 1995.

So if Justus’s recall is correct, then he could not be the same Peter
Hardcastle.

Cordially,

Charles

[Alister Taylor]

On Jan 7, 4:55 am, "Charles Carroll" <charles_carr...@comcast.net>
wrote:

Pretty sure Justus's recollection is wrong, I'm afraid. Pete went to
three Olympics and far too many world championships.
Of anyone I've ever rowed with, he is the best and most natural mover
of a double. (Or he shares similar technical weirdness with me).

[Zeebee]

http://www.jssm.org/vol10/n2/4/v10n2-4text.php
or, the same in printer friendly version:
http://www.jssm.org/vol10/n2/4/v10n2-4pdf.pdf

CONCLUSION
Collegiate rowers used higher stoke rates and lower stroke forces to
achieve a similar power output on the dynamic Concept 2 ergometer than
its stationary counterpart. These changes increased the
cardiopulmonary demand in some rowers and possibly reduced force
production in the primary movers. The differences were more pronounced
in males than females; this dichotomy may be due to dynamic ergometer
familiarity more than sex. These results have important implications
for athletes training on Concept 2 stationary and dynamic ergometers.
Depending on the athlete, stationary and dynamic ergometry may be
equally useful for cardiopulmonary fitness, stationary ergometry may
best improve force production, and dynamic ergometry may help rowers
maintain their feel for the water with more similar force profiles and
high stroke rates.

KEY POINTS
When rowing at a constant power output, all rowers used higher stroke
rates and lower stroke forces on the Concept 2 Dynamic ergometer as
compared to the Concept 2 Stationary ergometer.
When rowing at a constant power output, cardiopulmonary demand was
higher for all rowers, as measured by heart rate, on the Concept 2
Dynamic ergometer as compared to the Concept 2 Stationary ergometer.
When rowing at a constant power output, efficiency was lower for male
rowers on the Concept 2 Dynamic ergometer as compared to the Concept 2
Stationary ergometer.

[Kit]

On Jan 15, 4:47 pm, Zeebee <zbychobikeri...@gmail.com> wrote:
> http://www.jssm.org/vol10/n2/4/v10n2-4text.php
> or, the same in printer friendly version:http://www.jssm.org/vol10/n2/4/v10n2-4pdf.pdf
>

> When rowing at a constant power output, cardiopulmonary demand was
> higher for all rowers, as measured by heart rate, on the Concept 2
> Dynamic ergometer as compared to the Concept 2 Stationary ergometer.

I read this as saying a higher stroke rate at lower force requires
more effort than lower stroke rate at higher force. Right? Should it
make a difference?

[Charles Carroll]

>> When rowing at a constant power output, cardiopulmonary demand was
>> higher for all rowers, as measured by heart rate, on the Concept 2
>>Dynamic ergometer as compared to the Concept 2 Stationary ergometer.

> I read this as saying a higher stroke rate at lower force requires
> more effort than lower stroke rate at higher force. Right? Should it
> make a difference?

Kit,

Does "cardiopulmonary demand" equal "effort?" Could it be that it is the
word "effort" which is causing the problem?

A runner can run a marathon at a very high heart rate. On the other hand,
the heart rate of a weight lifter doing 10 reps of squats to failure may
never come close to max. So how do you compare the "effort" of the runner
to the "effort" of the weight lifter?

It is easy to compare "cardiopulmonary demand" because it is easily
quantified into numbers. But how do you quantify "effort," except as a
function of something else? And can you quantify effort as exclusively a
function of cardiopulmonary demand?

Cordially,

Charles

[Kit]

On Jan 16, 5:24 pm, "Charles Carroll" <charles_carr...@comcast.net>
wrote:

Good point. I read, but didn't perceive.

[amb...@gmail.com]

Very interesting your remark Charles, Peter Hardcastle has competed in 3 Olympics (rowing) the only rower to have qualified and rowed every scull at the Olympic for Australia 2000, 2004, 2008