Difference between damper settings and calories burned

[Citroen]

I put myself as a 7 to begin with, since I was rowing 4-7 hours/week sometimes more throughout the fall. The watch kept increasing it I think it was up to an 8.5 if not higher which seems too high - so realistically I think 7/7.5 is reasonable depending on month. (After it increased to 8.5 (between the marathon row, and the race) - I crashed physically and stopped using it (wasn't rowing either) for a while. I plan to get back to it once I finish my dissertation. I still don't feel completely recovered - rowing seems so much harder right now than it did pre Jan. ? ) I realize that the VO2 and TE estimations are highly dependent on activity class - but the HR data isn't.

I suspect you've got that set too high. I'm rowing six days a week around 10K to 15K per session and my AC is still only set to 7 (I don't allow the software to automatically increase it). AC 8.5 means you're close to the level of training needed for the 2012 Olympics. So your TE numbers will be showing on the low side.

[bloomp]

Work = Force x Distance x Cosine(theta)
Force = mass x acceleration

On the erg, mass remains constant, the only thing changing is the acceleration. Therefore, the only thing that changes from stroke to stroke is how we accelerate through the drive and the distance we row. You can only keep up the acceleration through a certain range of motion (can't lean back too far) but if you row too short you're not getting enough body movement.

Acceleration is then the only thing that matters (i hope everyone pulls in straight, that way the cosine calculates out to 1 and provides maximum work). Because we rely on the drag of the flywheel to allow for acceleration (note, this can be seen as friction vs. frictionless, where in a frictionless system it is impossible to gain any traction to move one way or another), there has to be some resistance within that to allow for any acceleration. Too little resistance, we cannot accelerate as much as we need to, too much resistance and we either cannot maintain proper form (and thus weaken the distance coefficient of the work formula), become exhausted earlier due to the effects of adding more drive through our legs to accelerate faster, or just struggle to obtain the peak acceleration.

Many coaches (especially on the water) talk about acceleration through the drive, and that's where this comes into play. If you only drive hard with your legs, you waste the output as soon as your back opens up, and your arms/trunk hardly pull at all. If you don't break the inertia of the flywheel/water with your legs, you rely too much on your arms/trunk to accelerate and cannot pull as hard. Therefore, constant acceleration (handle ALWAYS moving faster as it approaches your chest) can be seen as a limit.

The limit as the distance between the handle and your chest approaches 0 of the function acceleration x time^2 would be a useful graph to look at, and it would show you (as the one view on the C2 PM3/4 monitor shows) the increases/decreases in acceleration through the stroke. Ideally, it starts low and increases to an asymptote (like a natural log or log function) - showing that your legs have the slowest movement in breaking the inertia of the flywheel, but you continue to speed up as it translates into your back/arms. This is where the boat/flywheel is moving fastest etc. etc. etc.

How this relates to the flywheel damper setting is simple. You set the damper too high, it's too hard to break the inertia with your legs and you end up rowing poorly. You can damage your back and other trunk muscles easily as they are working very hard to try to maintain the acceleration to keep the work peaked. Set the damper too low and there's not enough inertia against our drive to let us accelerate to a proper speed. Because we determine how hard we pull, and therefore how fast the flywheel/boat is moving as the limit of that function approaches zero, we always TRY to accelerate through the drive, and it's in our best interest to find the one spot on that damper setting that lets us get a lot of inertia to break with our legs, but not too much that we cannot take a lot of strokes like that, and cannot accelerate properly throughout the stroke.

Just my view on it.
Paul

[Sheepster]

I suspect you've got that set too high. I'm rowing six days a week around 10K to 15K per session and my AC is still only set to 7 (I don't allow the software to automatically increase it). AC 8.5 means you're close to the level of training needed for the 2012 Olympics. So your TE numbers will be showing on the low side.

Well it was obvious that 8.5 was ridiculously high. I'll have to remember not to allow it to update automatically. At the time I set it to 7 I was rowing on average over 45,000m/week probably about 7K/day rowed (some days 10K others 5K) I never rowed less than 3/hrs a week and the majority of weeks I rowed over 5 hours. To be honest ~7K at a 3:30 pace average is equivalent to 10K at a 2:30pace. But since you seem to be much more fit and definitely row more intensely than I do, it does seem that my activity level should be lower than yours.

Going back to the suunto guide - it says that the weekly exercise is on top of sports or regular physical activity - so perhaps I should count the low intensity rowing as "regular physical activity" and the higher intensity rowing as "heavy exercise" since I don't participate in sports. That would then clearly lower the overall activity level.

Actually perhaps this is the solution to my current discouragement. I really struggled to get to even 5K during March Madness which used to be my daily minimum (without much difficulty). Rowing just feels so hard right now. If I start over again with a much lower activity class perhaps the feeling of accomplishment would help me feel more enthusiastic again. At least I could feel better about what I am currently capable of doing. The boost in morale probably would outweigh any disadvantages of setting the activity class too low in the short term and keep me from overdoing it.

I just wonder though if it would be accurate then about the "aerobic benefit" since it seems that even low intensity rowing could put me into the aerobic zone - since my HR goes up quite easily even at paces that don't feel very intense/aerobic. But then I do usually spend short periods of rowing more intensely even during slow rows. I guess I'll need to experiment more.

I've wondered if the firstbeat training software would be of value in planning workouts. That's on my list of things to try post-dissertation.

[iain]

If the software upgrades Sheepster to near Olympic status, it does not seem to be being realistic. If this is a general problem, is there a flaw in the software or is it just not appropriate to erging? I klnow nothing about how it operates (Dougie, that's your cue if you read this...) but is it more appropriate for a sport which uses a smaller portion of our muscles (running?) which may not produce such high HR rates for such long periods for the average serious participant?

- Iain

[peterd099]

I think this concern about more effort expended for higher damper settings but not increase in calories reflects the fact that the Concept2 PM3 does NOT in fact take damper setting in account when calculating calories. The damper is simply an anlogue mechanism, it has no impact as far as the PM3 is concerned. So if you row N metres you will, according to the PM3, always expend the same number of calories. What the PM3 SHOULD be doing (if it worked properly) is reflect a higher expenditure of calories per minutes at higher damper settings.

[iain]

I think this concern about more effort expended for higher damper settings but not increase in calories reflects the fact that the Concept2 PM3 does NOT in fact take damper setting in account when calculating calories. The damper is simply an anlogue mechanism, it has no impact as far as the PM3 is concerned. So if you row N metres you will, according to the PM3, always expend the same number of calories. What the PM3 SHOULD be doing (if it worked properly) is reflect a higher expenditure of calories per minutes at higher damper settings.

I thought that the calories were calculated from energy output (albeit that this may be an estimate itself calculated from the average pace rather than the actual energy expenditure and therefore not adjust for the inefficiency of changes in pace). Hence, pulling the handle at the same speed will not give the same calorie usage as the power increases in proportion to the drag factor.

The infamous assumption of 300kcal/hr for merely going up and down the slide has a huge impact on the calories shown for slower paces. When I was preparing for a 24hr row, I adjusted this to assume that this was derived from 28 strokes per minute. I believe that the calories going up and down the slide are proportional to the cube of rating, so I assumed exercise at 20SPM would give an additional (20/28)^3 ~ 100 KCal/Hr for a 75Kg rower rather than the 300 assumed by the rower. I think that this error will swamp any effects of the damper setting.

- Iain

[mikvan52]

Just read all the posts on this thread for the 1st time... Very Interesting.

In summation: Can it be said that as far a damper selection goes, when you're interested in burning calories: Just set the drag factor (damper) where you feel comfortable and go long and fairly easy.

1. You won't wear yourself out or get stale
2. The next session (subsequent day) will seem easier.
3. You needn't be too precise about calories burned... those who "go long" burn lots of calories anyway.

I am a lifelong lwt rower who has seen the benefits of not overdoing it, both my own training and the hundreds of young rowers I've coached.
If weight reduction is the key.. do not work too hard

[Steelhead]

If I burn 300 calories lifting heavy weights, it really exhausts my muscles; if I burn 300 calories riding a bicycle, it is fun; if I burn 300 calories sprinting it hurts; if I burn 300 calories jogging it feels good. I still only burn the same 300 calories even though my muscles feel more exhausted doing one than the other. Mutatis mutandis, the drag factor/resistance on the erg works the same way. If I use a 10 then I feel like I'm lifting weights but I'm still burning the same calories that I would using a 1 that is just a fun row. Is the foregoing a correct analogy?

[gregsmith01748]

I'm just starting to learn about EPOC (excess post-exercise oxygen consumption). Apparently, depending on the intensity of the workout, you will burn more or less energy after the workout is over. A side note, the EPOC effect roughly correlates to t he list that Steelhead included. Weight training and intervals have the highest EPOC, while steady state workouts the lowest. The effect appears to be moderate (like 10% additional calories), but measurable. This might all be bunk, but it is making for interesting reading. It looks like the Suunto on the PM4 can actually provide an estimate.

[carlb]

I must say that the drag factor is confusing me too. If we take the term drag strictly, I don't see how higher drag settings require the same amount of energy as lower ones. Drag is defined as :
"the phenomenon of resistance to motion through a fluid"
The higher the resistance, the higher the energy required to move for the same distance. As an example, on the water, the higher the resistance to motion (air density, aerodynamic of the shell), the higher the number of watts required to move the boat at a given speed. This has nothing to do with which muscles are used :
drag force = 1/2 * air_density * coefficient of drag * frontal area * speed^2
Watts = drag force * speed

This seems to align with how C2 describes the drag setting (heavier boat).

I don't claim to understand physics, but this is confusing.

JC

My understanding of this.....
The PM calculates the watts of power you the rower added to the flywheel by spinning its mass during the Drive.
Those watts are converted using a formula into pace/500.

I tend to think the Drag Factor only affects the recovery when affects how fast the flywheel decelerates
If the Drag factor does affect the drive then certainly the PM adjusts your watts and your pace. I think I read somewhere that the PM measures DF on every recovery and uses that for the next stroke.


This page has a discussion on Power Measured
http://www.atm.ox.ac.uk/rowing/physics/ ... l#section8
"With variable damping, the acceleration of the flywheel dω/dt is measured during the stroke phase, and related to the net torque (=applied torque minus drag torque, Eq. 2.4): "

I also found interesting section 13
"Effect of Rating - It is well known that most erg world records (on Concepts, at least) are set at much lower rates than used in racing boats over events of similar duration. There are probably two reasons for this
2. The ergometer rower has to perform additional work accelerating/decelerating their bodyweight each stroke- in a boat the body moves much less relative to the centre of mass of the whole system, so there is less of a penalty for higher ratings."

For a HM or FM that take 1.5 to 3 hours lowering the drag and could allow lower SPM so could save some work for which the PM does not give you credit. Wonder if anyone has any experience with this? And how much they lower it?

[Bill]

Hello,

This discussion looked interesting, here is the way I think about these things.

I believe that when I have a high DF then I spend more time on the drive part of the stroke.

The lower DFs allow me to apply a sharper quicker drive - it "feels" as though I must do a quick explosive drive simply to "catch up" to the spinning flywheel and be able to apply more power to it.

So on high DF, I have a higher Drive : Recovery ratio and I will spend more time in the workout pushing with my legs and pulling with my arms, then I have to quickly recover to be in time for the next stroke.

On the lower DF, I believe that I have a lower Drive to Recovery ratio - so I spend less time driving and more time recovering and then I dont feel as tired at the end of the workout, even though the erg measures the same amount of work done on the flywheel.


Regards

Bill

I liked the analogy of lifting a feather in an earlier post - that feels right to me, however, I cannot find the correct words to explain more clearly why this fits with the way I think about it.

Regards

Bill

[iain]

IIRC, the drag is estimated from the recovery phase, but the impact of this is built into the energy calculation. i.e. the greater handle speed at lower drag (for the same "pace") is neutralised by the lower "drag" constant in calculating the energy. In fact at higher drag, due to the increased drop off in power dissipated over the recovery, to achieve the same average power then a higher power must be generated during the drive (ignoring the impact of the shorter recovery).

The lower drag I use for FM is to delay the tiredness of my muscles. I use a higher rating than I would normally require for the pace for a similar reason. I am sure that there would be a reduction in calories burned as a result of the slower recovery, but how this compares to the loss of "credit" for the increased acceleration required to "catch" the flywheel and the higher acceleration of the drive to reach the higher speed I don't know. Much more important is that the CV load is sub-maximal and so using a higher rating shifts some of the load back to the CV system rather than the skeletal muscles. This will increase calories burned due to the greater distance the oarsman has to travel, but for an FM, if fully fuelled I don't find this limiting. In UM rows however, I do try and maintain a lowish rating as then the calorie usage matters (delaying when you hit the wall).

- Iain