Proper Powerstroke graphs?

[Dale_R]

I am not sure I am calling it the right thing, but on the PM4 display for every stroke you can see the power output per stroke on a graph. Does anyone have a link for examples of what the proper shape and duration of the graph should look like?

With a little experimentaion on my form and stroke rate, I can get vastly different shapes and durations. I would think that one would want and expect to see different shapes depending on training goals for that set.

Surely there must be some sort of visual guide on line to help compare ideal waveforms by goal.

Any links would be appreciated.

Thanks

[PaulS]

There is a "Power" graph display, but it is more of a bar graph.

What I think you may be asking about is the "Force" curve display, which updates on each drive in near real time.



The Top row has two units being plotted, the Purple is the Force unit and the Blue is similar to the Power unit in the examples on the second row.

My personal preference is for the center profile (I only use the Ergo to improve what moves boats), however one thing that should be worked on regardless of profile is to avoid any concave bits in the force, it should always fall off smoothly.

An idealized profile would be rectangular (on the Ergo), getting the most power (area under the curve) for the least peak pressure, but humans don't do things in an instantaneous manner very well. When transfering the idea to what to do in a boat, the more "front loaded" profile makes more sense due to the way an oar blade works, however it is the most difficult to master due to the precise timing required along with good blade work. (Chains and cogs are a rigid connection without any technique, oars have flex and the requirement of being buried well before they can connect solidly with the water.)

[philrow]

Thanks for this post, Dale and Paul. I was actually just about to post about this topic.

Specifically, I seem to be having problems getting what I'm told is an "ideal" curve. The "coach" here at school (the one that doesn't show up for his practices, sends out vague training through e-mail, isn't around to help technique or answer questions like this, and is ultimately scaring me away from rowing at this school I'm at) says that a bell curve is ideal. But, from what I read and what I see, that doesn't seem to be the case. Whether it is or not, I'm definitely not able to cultivate one. Things probably smooth out at higher rates, but recently at 1' 20spm 1:42 and 1' 26spm 1:32 pull-pressure pieces, I would end up with curves looking similar to the middle one in the posted image here except it would be a little more drawn out later in the stroke, and usually with a bit of an increase in power about the time I get to arms in. This occurs even when I go for as quick and aggressive of a drive as possible. Also, I'm not jerking in with my arms, and I "rarely/if ever" upset a boat when I get to arms in... and yet I consistently seem to be applying some decent deal of pressure at that point.

My curve looks somewhat similar to NavigationHazard's seen here: http://youtube.com/watch?v=YdDlztY-w4s He too seems to have a bit of a change in the curve about where he does arms in, except mine is more pronounced.

Does anybody have any input? Is my stroke ok anyway?

Phil

[michaelb]

Coach PaulS's images are from his rowing software, ergmonitor, which is also what NavHaz uses. Ergmonitor predated the force curve on the PM by many years, so he can get some credit for focusing on the concept of a force curve. My impression is that there are differences in how the force curves are displayed between the PM and EM, with EM being much more precise, and the PM being a bit truncated at the start and less detailed overall.

The basic explanation by PaulS and others is for the force curve to look like a "left leaning haystack". The left leaning shows the sudden power increase at the beginning of the drive, the smooth rounded top of the haystack shows even power application throughout the drive. So that may be the ideal, although the 3 images above show alternate force curve profiles.

But for my own purposes, I stopped focusing on the force curve display because without on site professional coaching, I think you can cheat the display and develop bad habits as result. At least for me, I think in order to get my curve left leaning, I was pulling early with the arms and not starting the drive with my legs. So be careful about how much you focus on it.

Phil: I am no expert (and NavHaz may be an expert, certainly PaulS is), but my concern about a dip in the curve is that shows uneven force application and a sign that you may not be sequencing the elements of your stroke, legs, back, arms, correctly. I get a dip when I am not smooth with my back, I think, lurching early and lurching late possibly.

[PaulS]

Thanks for this post, Dale and Paul. I was actually just about to post about this topic.

Specifically, I seem to be having problems getting what I'm told is an "ideal" curve. The "coach" here at school (the one that doesn't show up for his practices, sends out vague training through e-mail, isn't around to help technique or answer questions like this, and is ultimately scaring me away from rowing at this school I'm at) says that a bell curve is ideal. But, from what I read and what I see, that doesn't seem to be the case. Whether it is or not, I'm definitely not able to cultivate one. Things probably smooth out at higher rates, but recently at 1' 20spm 1:42 and 1' 26spm 1:32 pull-pressure pieces, I would end up with curves looking similar to the middle one in the posted image here except it would be a little more drawn out later in the stroke, and usually with a bit of an increase in power about the time I get to arms in. This occurs even when I go for as quick and aggressive of a drive as possible. Also, I'm not jerking in with my arms, and I "rarely/if ever" upset a boat when I get to arms in... and yet I consistently seem to be applying some decent deal of pressure at that point.

My curve looks somewhat similar to NavigationHazard's seen here: http://youtube.com/watch?v=YdDlztY-w4s He too seems to have a bit of a change in the curve about where he does arms in, except mine is more pronounced.

Does anybody have any input? Is my stroke ok anyway?

Phil

The "Bell curve" would not have a quick enough beginning, and would also show a concave bit near the end. That said, nip off the a bit at either end and it wouldn't be terribly horrible, ending with what we would call the "Fat middle" type of profile.

Nav's video is showing some high for/low rate work and when trying to get the best pace under those circumstances it is tempting to really haul with the arms. This is okay on the Erg, but would be very unlikely to be productive in the boat because the blade is slipping at that point and will only slip faster rather than drive the boat ahead, it will produce what looks like an impressive puddle, but unfortunately it was not as productive a puddle as might be achieved.

A couple questions:

Do you think your arms are stronger than your legs?
Which is more likely to be able to produce more peak force?
If the actual Peak is after the legs are done, what area of the stroke needs work?

Nav has improved quite a bit since that was recorded, with an earlier peak, smooth fall off, and no loss in overall pace.

I'd prefer to see a profile like this:

Which keeps the peak in an area where it will be more useful in prolonging the impulse of acceration to a boat.

The scale seen along the bottom corresponds to the drive time in 10ths of a second.

Note: ErgMonitor was introduced several months before the PM3 displayed version, only because I'd pestered C2 about doing it for a long time and kept getting told that they weren't planning on such a feature so Mike and I got together and did it ourselves. The lastest version on the PM3/4 is far better than what was introduced in the original firmware, so much more of the stroke is visible these days. EM still has an advantage regarding detail, units, and scale, but the PM's display has some utility for sure.

[philrow]

My problem is not that I peak at arms in. I suppose the link I posted to Nav's video wasn't a good similar curve. Take the one you posted, except at around 5/6 10ths, where the break is there, add a second, vastly smaller "peak." It's not significant by any means -- hardly a peak. But, it draws out the length of the decline in force for the stroke, making it even more lopsided.

[PaulS]

My problem is not that I peak at arms in. I suppose the link I posted to Nav's video wasn't a good similar curve. Take the one you posted, except at around 5/6 10ths, where the break is there, add a second, vastly smaller "peak." It's not significant by any means -- hardly a peak. But, it draws out the length of the decline in force for the stroke, making it even more lopsided.

So you mean that it adds what might be characterized as the front end of a VW bug? If so, that would make for a concave shape on the downside, which signals a loss of force through the transition during the Drive, quite common for women, due to there generally less proportional upper body strength, but with training, they can bump the 3/4 point up slightly to get a better taper off the secon half.

[philrow]

Nevermind this post, my attempt to illustrate the curve failed miserably. I'll try to get an illustration or picture up.

[Nosmo]

Paul,
My style is the Grinko (at least when I'm rowing well), my doubles partner is the Rosenberg (actually his force curve looks more like the rosenberg energy--very symetrical and sharply peaked. He is a very experienced coach. His force curve is very consistent and very smooth. Mine is not always but has improved dramatically this year.
Obviously you would recommend both of us using the Grinko style but I don't think I am likely to change his stroke. He does not recommend that I trying to change mine to match his.
How important do you think it would be for both of us to be using the same style? Should we just leave well enough alone?

Did you add the scale to the bottom of the force curve, or are the new PM's coming with it?

On the erg monitor display, you show thin black lines that divide the stroke up into four parts. Why did you choose that shape?

Thanks

[PaulS]

Paul,
My style is the Grinko (at least when I'm rowing well), my doubles partner is the Rosenberg (actually his force curve looks more like the rosenberg energy--very symetrical and sharply peaked. He is a very experienced coach. His force curve is very consistent and very smooth. Mine is not always but has improved dramatically this year.
Obviously you would recommend both of us using the Grinko style but I don't think I am likely to change his stroke. He does not recommend that I trying to change mine to match his.
How important do you think it would be for both of us to be using the same style? Should we just leave well enough alone?

Did you add the scale to the bottom of the force curve, or are the new PM's coming with it?

On the erg monitor display, you show thin black lines that divide the stroke up into four parts. Why did you choose that shape?

Thanks

It's better to be similar in profile if you can manage, it's also easier for you to change than it is for him (most likely). All you have to do is not "hop on it so much" and think "big middle" (don't really try to force the middle, just think it). It would be worth a try to see if it helps with the speed for effort pay-off.

I added the scale at the bottom, based on a 1.2 second scale, and that there is still a bit being missed by the PM3/4 (~0.05sec).

The Stroke Phase Guide (thin black lines) is a normalized representative of the blade tip advance during the drive, in quarters.
1: Blade advancing toward the finish line. High lift forces.
2: Holding relatively still along the line of boat travel. Medium lift, increasing Drag.
3: Retreating a bit during the stall (Slip and turbulence)
4: Small advance, but also a high lift area.

It came about from some work done by Ken Young at the University of Washington, regarding lift forces involved in sculling.

[Dale_R]

Sorry about the drive by posting, I've had a little excitement the last week or so... (see my thread in weight loss)

Needless to say..

Excellent responses, thanks for the visuals.


I am wondering if the goal of the rowing session isn't speed or power, but weightloss and distance if the curve would be much flatter and longer?

Or should I still go for the higher angle of attack curves even for this?

[PaulS]

Sorry about the drive by posting, I've had a little excitement the last week or so... (see my thread in weight loss)

Needless to say..

Excellent responses, thanks for the visuals.


I am wondering if the goal of the rowing session isn't speed or power, but weightloss and distance if the curve would be much flatter and longer?

Or should I still go for the higher angle of attack curves even for this?

Most of weight loss is going to depend on moderate efforts and time in the saddle. I.e. burn as many calories as you can during the session. Of course the more lean body mass that you have, your BMR (Basal Metabolic Requirement) will increase, so a few more intense sessions to build strength and muscle mass are also helpful.

As far as the curve shape is concerned, since the stroke components (Legs, Torso, Final Draw) are still the same and will have relative strengths to work with, the Quick rise and subsequent tailing off will be about the same as for other training. Strongest muscles producing the most force, less strong remaining in proportion.

[JimR]

I am wondering if the goal of the rowing session isn't speed or power, but weightloss and distance if the curve would be much flatter and longer?

Most of weight loss is going to depend on moderate efforts and time in the saddle. I.e. burn as many calories as you can during the session. Of course the more lean body mass that you have, your BMR (Basal Metabolic Requirement) will increase, so a few more intense sessions to build strength and muscle mass are also helpful.

Something I have been working on ... adding weight lifting to my workouts. I'm working on weight loss but I'm thinking that an erg is not the best way to build lean muscle.

Aside from that, it seems like erg training for weight loss would focus on time (up to a point) but then revert to intensity. If I erg (for example) 60 minutes at a 2:30 pace today then in 3 months I would expect I should be doing the same 60 minutes at a faster pace than 2:30 to keep the calories burned the same ... or is this not the case???

JimR

[PaulS]

I am wondering if the goal of the rowing session isn't speed or power, but weightloss and distance if the curve would be much flatter and longer?

Most of weight loss is going to depend on moderate efforts and time in the saddle. I.e. burn as many calories as you can during the session. Of course the more lean body mass that you have, your BMR (Basal Metabolic Requirement) will increase, so a few more intense sessions to build strength and muscle mass are also helpful.

Something I have been working on ... adding weight lifting to my workouts. I'm working on weight loss but I'm thinking that an erg is not the best way to build lean muscle.

Aside from that, it seems like erg training for weight loss would focus on time (up to a point) but then revert to intensity. If I erg (for example) 60 minutes at a 2:30 pace today then in 3 months I would expect I should be doing the same 60 minutes at a faster pace than 2:30 to keep the calories burned the same ... or is this not the case???

JimR

While the nominal calories/hour may not be accurate, they will certainly be relative, so a faster pace for 60 minutes will burn more calories. It's sort of like the "100 Kcals/Mile on foot" it is basically stable whether walking or running, but it's over quicker when running. Higher power output = More calories expended.

[Nosmo]

Most of weight loss is going to depend on moderate efforts and time in the saddle. I.e. burn as many calories as you can during the session. Of course the more lean body mass that you have, your BMR (Basal Metabolic Requirement) will increase, so a few more intense sessions to build strength and muscle mass are also helpful.

Something I have been working on ... adding weight lifting to my workouts. I'm working on weight loss but I'm thinking that an erg is not the best way to build lean muscle.

Aside from that, it seems like erg training for weight loss would focus on time (up to a point) but then revert to intensity. If I erg (for example) 60 minutes at a 2:30 pace today then in 3 months I would expect I should be doing the same 60 minutes at a faster pace than 2:30 to keep the calories burned the same ... or is this not the case???

JimR

While the nominal calories/hour may not be accurate, they will certainly be relative, so a faster pace for 60 minutes will burn more calories. It's sort of like the "100 Kcals/Mile on foot" it is basically stable whether walking or running, but it's over quicker when running. Higher power output = More calories expended.

There will also be a change in efficiency of converting food energy to work over time as you get in to better shape and get used to erging. I've seen measurements on cyclist and a novice may be about 18% where as pro will be more like 24% (couldn't find the link so take these as apporximate), so the novice would burn a lot more calories then the pro at the same power output. However as you get into shape it becomes much easier to work harder so you will have an easier time burning calories. Also it takes a long time to become more efficient, so in the short run I wouldn't worry about it much.