Difference between damper settings and calories burned

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jcm
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Post by jcm » March 31st, 2009, 10:42 pm

Citroen wrote: The energy input to row 2:00 splits doesn't change due to damping, length of stroke or stroke rate.

http://home.hccnet.nl/m.holst/ErgoDisp.html
http://www.atm.ox.ac.uk/rowing/physics/ergometer.html


Citroen,
Not that this is critically important to enjoy rowing, but you are kind of confusing me more ... In the last link you've provided, it says :
Changing the damping alters the relationship between power and flywheel speed
Which seems to indicate that damping will alter the pace.

... Thanks for the pointers.

JC

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Post by Bob S. » April 1st, 2009, 12:33 am

jcm wrote:
Citroen,
Not that this is critically important to enjoy rowing, but you are kind of confusing me more ... In the last link you've provided, it says :
Changing the damping alters the relationship between power and flywheel speed
Which seems to indicate that damping will alter the pace.

... Thanks for the pointers.

JC
The pace is dependent on the power, not the flywheel speed. With the damper closed, i.e. set on zero, the drag factor will be low, and there will be minimal air flow. The application of a set amount of power will give the flywheel a relatively high speed and the slowing of the wheel will be gradual.

With the damper wide open, i.e. set on ten, the drag factor will be high, and the airflow will be maximal. The application of the same amount of power won't give as much speed to the wheel because it is having to push a lot more air and the slowing of the wheel will be relatively rapid.

In either case, the monitor determines the work done by the rate at which the wheel slows down as well as by its speed.

So — same power and same pace, but different flywheel speeds. The monitor is designed to determine the work done and presents the rate of that work done as pace or watts as you choose. (Calories are another matter, since that value includes a bugger add-on to account for work done unrelated to the spinning os the wheel. I wanted to call it a bugger "factor" but it is a matter of addition rather than multiplication.)

Bob S.

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Post by jamesg » April 1st, 2009, 12:52 am

The erg measures how much work we put into each stroke when we pull the handle. The point is that this Work is the product of TWO elements, force x length, which is the engineering definition of Work. If either of these elements is small, the product, work, is small too.

The erg does NOT measure how much energy we have to burn within our muscles to deliver that work. It can only assume a certain production efficiency (25%).

However the actual efficiency depends on drag. We are free to choose the drag that lets us deliver the maximum amount of work for the amount of energy we burn. Very high and very low drag lead to low efficiency - which means we may get tired, but without delivering much work to the handle.

These two, energy burnt and work delivered are NOT in a fixed relationship.

Incidentally (or maybe not), we deliver most work when the drag is around 110-130, because this enables a fast and long pull and we can use our legs. Doing this is what gets us fit, because leg muscles are large and place a large load on our CV system. Just what's needed to get fit.

So the moral is, if you want to get fit, learn to row. Technique is all, it gets you fit and fast.
78y, 188cm, 87kg, last seen MHR 163. 2k (24 May 19) 8.46.6@22

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Post by Sheepster » April 2nd, 2009, 12:19 pm

jamesg wrote:The erg measures how much work we put into each stroke when we pull the handle.

....

So the moral is, if you want to get fit, learn to row. Technique is all, it gets you fit and fast.
Reading this and given my experience, I would say the moral is get a heart rate monitor and don't rely on the erg.

The erg doesn't measure how much work we put in at all. It measures output. It then makes assumptions about the work put in based on that output. The assumptions include an assumption about what kind of person we are (i.e. the 80kg person) to estimate work put in which may not reflect reality. It also assumes that at a given output the calories burned is the same which is clearly not true.

A fit person can put in little effort and get better output than an unfit person who may be working very hard for a "slow" pace. The unfit person will probably be burning more calories - though. That's why intensity and/or duration has to increase as one becomes more fit to get the same calorie burn.

That's why I find the Suunto monitor that measures not only heart rate but also estimates "training effect" useful because it takes some of that into account (although it too has its idiosyncrasies - like the time it decided I was at the level of an Olympian athlete :shock: ha ha ha )
Basically as one exercises more and over time the monitor requires greater input to achieve the same training effect.

Heart rate monitors are not perfect but at least they measure how much a certain exercise effort increases one's heart rate. It will be able to tell that the slow pace row hasn't budged the world champion rower's but has increased the rowing newbie's significantly and the calories burned estimate will be more accurate than the concept 2's.

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How accurate are HR monitors at estimating calories burned?

Post by iain » April 2nd, 2009, 1:20 pm

I am not so sure that it follows that C2's energy method is much worse than the HR monitor. I beleive that HR monitors assume that the energy utilisation is a function entirely of Heart Rate (i.e. what they measure), while C2 uses work carried out by the flywheel. I accept that HR monitors adjust for weight, but not for stroke volume and hence will relatively underestimate the energy used by those with exceptionally large stroke volumes as they will underestimate the blood circulation and hence the oxygen consumption as well as the energy used by the heart itself. as increase in stroke volume will be one of the key changes for someone doing the same workout at a lower HR, i think this is likely to be significant.

2 people of the same weight who generates the same power at the same rating with an identical stroke will be generating the same external work. I appreciate that producing more energy anaerobically will consume more energy (as the lactate will be reconverted for reuse or storage) and it may be that more energy is wasted by one than the other through energy leakage etc. But if one does it at high HR and the other at a more modest level, why should that radically alter the energy usage? I would say that an olympic oarsman doing the same time of exercise at the same heart rate as a similar sized less fit person would require much more food to maintain their weight. I'm not sure the HR monitor would predict this, while an erg would show a faster pace and hence show a higher energy consumption. hence amending the C2 calculation for the rowers weight and rating might well provide a more accurate estimate than an HR monitor.

- Iain

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Post by Sheepster » April 2nd, 2009, 7:09 pm

Depends on the Heart Rate monitor - mine measures heart rate and heart rate variability. It also has me input height, weight, maximal heart rate, age, sex, activity level, and allows you to put in your Fitness MET (if known - otherwise they estimate), and altitude (don't really use this) - so it does take into account other variables. I think there is one monitor that directly measure breathing rate as well - but that's not common.
I admit - I don't personally really follow calorie expenditures on either the C2 or HR monitor. I don't find it useful for my goals which are related to aerobic fitness. But I do find the HR monitor more useful for training for that goal than the C2 monitor.

But because the heart rate monitor is measuring a physiological variable directly, I do think they are better at comparing variations in a single person. i.e. if today I row 20 minutes at a HR of 120 and yesterday I rowed for 20 minutes at a HR of 180 - I know that yesterday's workout was more intense. Of course I'll see a different power output as well - but for subtler differences I find HR more consistent with perceived effort (which is also reasonable measure) than power output per the C2. I agree HR is not as useful in comparing between people.

In the example of the rowing newbie and world champion rower - the two are generating the same power output on the c2 monitor - but they definitely do not have an identical stroke. Certainly a major component of why the world champion will expend fewer calories is the greater efficiency of their stroke - they are more efficient at translating their energy consumption into rowing power so they use less energy for a given output. Their heart rate and breathing rate will be lower (fewer calories burned here as well - although a much much smaller component).

It's the energy wastage - that primarily makes the power output less accurate estimate for energy consumption. Especially for a relative beginner where there can be a lot of variability in technique which leads to variability in energy wastage which leads to variability in the relationship between power output and calorie consumption. For the experienced rower it may be that technique is more constant and HR is more variable. Obviously combining the two (HR & Power output) is better than relying on one or the other alone.

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No truly acurate calorie counting method

Post by iain » April 3rd, 2009, 3:12 am

Sheepster, I agree that the HR monitor might be better. I was over stating my case above. In short without impractical equipment for everyday training, it is not possible to measure calories used that accurately. However it is impractical to measure calories in that accurately as well. So at least the HR monitor and C2 give a guide and then following long term weight loss with a regular diet and trainingprogram will be the best way to ensure that a balance is maintained.

Fopr balance, I admit that where the C2 falls down is at very low intensity levels. In the gym I use I regularly see people doing 400-500 Cal/hr (29-58W, 3:00-3:50/500m) to a set calorie amount. Given that 2/3 of the calories recorded are the estimate of calories for sliding up and down without pulling the handle, here the C2 record is next to useless. Also I believe that the 300Cal/hr "allowance" overstates the use at low ratings.

- Iain
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Post by jamesg » April 3rd, 2009, 3:14 am

The erg allows for lack of fitness and bad technique by including in its kCal total the 300/h. One allowance is enough. The 25% efficiency presumably is chemistry, we're considered as fuel cells.

Beyond that, it would seem quite ridiculous if not almost impossible to work hard on the erg, but not put that work into the handle.

The erg is not designed to measure kCal, but the work done by the flywheel as it decelerates. Such a simple calculation of kCal cannot expect to be closer than 10% I'd guess, probably good enough for most purposes, whatever these may be. To get any serious accuracy would require come very expensive calorimetry I should think.

Have you seen discrepancies larger than this between differing systems, but not due to the 300 free of charge? I suspect these differences are small, especially if measured against the standard cream bun or carbonara.
78y, 188cm, 87kg, last seen MHR 163. 2k (24 May 19) 8.46.6@22

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Applying above to the author s stats

Post by iain » April 3rd, 2009, 3:39 am

Vsaksena, As stated above the 300 cals/hr allowance may be way off and so is a major source of error at lower power outputs. Increasing from 11k to 12k in an hour (a very creditable improvement) is an increase in power and therefore "useful" work done of 30%, while the calories burned are only 14% higher per the monitor as the 300 doesn't change. However this 300 includes what you would have burned at rest in addition to making assumptions about the length of the stroke and speed of movement on he slide. The extra calories from moving your weight along the slide per an earlier post increases with teh cube of the rating, so is far from constant. So I would concentrate on the 30% increase in work rather than the more miserly C2 calorie count (although not to the extent of an extra 30% of food intake!)

- Iain

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Post by Citroen » April 3rd, 2009, 5:10 am

I think you have to go back to how C2 came up with the mythical 300(k)Cal/h number.
Jon Williams of Concept2 (12 Aug 04) wrote: The 300 kC/hour has always been our best approximation for keeping alive and awake and going through the rowing motion at a reasonable stroke rate on an erg with the flywheel removed. This was arrived at from internal experiments and observations, data from Fritz Hagerman and studies done at Ball State.
Without knowing the sample size and how well trained the subjects of that testing were that is largely equivalent to having a random number plucked from the ether. The calories display tends to be used by the folks hoping to achieve weightloss, but they are probably so far from the sample group that it really is meaningless.

As a gym instructor said to me, it does give them a target to aim for. It's common for them to give the instruction to newbies "Row for about five minutes until it displays 100 calories".

The watts display (and the pace calculated from that with the 2.8 fudge factor) is more accurate and therefore more useful.

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Post by Sheepster » April 3rd, 2009, 10:58 am

Citroen wrote:I think you have to go back to how C2 came up with the mythical 300(k)Cal/h number.
Jon Williams of Concept2 (12 Aug 04) wrote: The 300 kC/hour has always been our best approximation for keeping alive and awake and going through the rowing motion at a reasonable stroke rate on an erg with the flywheel removed. This was arrived at from internal experiments and observations, data from Fritz Hagerman and studies done at Ball State.
Fritz Hagerman - the one whose data the V02 calculator is based on. My beginning 2000m times gave me a NEGATIVE V02 using his calculator. :shock: :lol:

Now that I (re?) discovered the calorie adjustment calculator -

I went back to a couple of my rows and the c2 monitor isn't that far off:

I rowed 10, 000 m in 55:58.9 minutes (2:47.9) - the Suunto estimated a calorie consumption of 563 kcals (included 7 extra minutes surrounding the workout.) I don't have the exact c2 data but using the various equations - I calculated that the c2 would have given 599 kcals and with weight adjustment (I used 60kg) 526.

I tested again with a 30minute row (performed 2 days later) (5600m, 2:40.7 split). I had the monitor on for 47 minutes - total kcal 372. Actually calculating the concept2 calories with weight adjustment gave me 372.

But the real issue is this - for the 30 minute row my HR was > than 180 for 6.5 minutes and between 160-180 for 23.5 minutes. And with the 10,000 meter row my heart rate was between 160 and 180 52:40 minutes. These workouts were considered in the "overreaching" range by the H.R. monitor.

From the standpoint of aerobic fitness - it's a easier for me to judge appropriate effort using the HR monitor (and its fancy training effect and EPOC calculations) than it is using power output. It becomes obvious why, if I did care about calories - long slow rows are necessary to accumulate them. A long row with a split of 3:45 still had my heart rate between 140-160 for over 55 minutes and over 160 for a couple minutes. (140-160 is actually within 75-85% of my maximum heart rate.) That was encouraging for me because faster rows can really exacerbate some musculoskeletal issues that I have. So even if a world champion rower and I burn similar amounts of calories at the same power which clearly has to be set to the low level that I can actually obtain and sustain (although I still think they might burn fewer) - I can clearly obtain aerobic benefit from rows which would have minimal to no aerobic benefit for them.

Much of the information and discussion of power/pace on these forums or for training - are aimed at people with much faster splits. And I think it can be difficult for the deconditioned newbie, particularly a lightweight female, to know how to appropriately aim their rows from the power ratings/pace given that there is little good information for comparison. That is the main reason I think the HR monitor is useful not because if its potential greater calorie estimation accuracy. I certainly felt a lot less discouraged about rowing so slowly and about the times where I have to slow down from the musculoskeletal standpoint.

Connecting workouts with their effect on my CV system, helps me remember that even though I rowed for over 7 minutes longer than the other 14 rowers in the 6k during my first race (it's so lonely rowing alone) my split of 2:34.6 was still a real accomplishment for me (especially given that it was after a P.B. 2K 4.5 hours earlier) :) (Don't actually know what my HR was - but this was only 4 weeks after the 30 minute row above.)

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Post by Citroen » April 3rd, 2009, 11:31 am

Sheepster wrote:I tested again with a 30minute row (performed 2 days later) (5600m, 2:40.7 split). I had the monitor on for 47 minutes - total kcal 372. Actually calculating the concept2 calories with weight adjustment gave me 372.
You are so far off the end of the bell curve that most numbers whether derived by the PM3 and adjusted with the website or from the Suunto software won't work for you.

What activity class do you have in the Suunto software, that makes an enormous difference to how it uses the R-R and EPOC data to calculate a TE and other values.

Also the paces you've give (even for an unfit lady) tend to point to technique issues.
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Post by iain » April 3rd, 2009, 12:33 pm

Citroen wrote:
Sheepster wrote:I tested again with a 30minute row (performed 2 days later) (5600m, 2:40.7 split). I had the monitor on for 47 minutes - total kcal 372. Actually calculating the concept2 calories with weight adjustment gave me 372.
You are so far off the end of the bell curve that most numbers whether derived by the PM3 and adjusted with the website or from the Suunto software won't work for you..
I would be surprised if Sheepster is off the bell curve, I would have said that the above times would be fairly typical for a lightweight female. The O'Neil fitness test shows 2:20 split for 4mins as Average performance, I would have said that was no better than a 2:35 6k. It is easy to forget that times of people recorded on the Forum are for some of the fittest fastest people around as well as forgetting the differences of people in the slower classes. However, teh C2 calorie counter is dubious as the calories used pulling the handle will be comparable to those sliding up and down and surviving.

- Iain

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Post by Sheepster » April 5th, 2009, 7:05 pm

Citroen wrote:You are so far off the end of the bell curve that most numbers whether derived by the PM3 and adjusted with the website or from the Suunto software won't work for you.
Which bell curve? Actually my two best efforts the 2K in 9:54.2 minutes and the 6k result mentioned above per the rankings are 80-82% in my weight and age class - not great but still on the bell curve. If one considers that those ranking results might be skewed towards faster rowers who are probably more likely to rank times than the group of all rowers - I am probably closer to average or slightly below average. (Haven't done a serious attempt the O'Neill fitness test recently but in Sept I was at 817 m (my best 2K time in Sept was 10:09.5 - but given my improvement in the 2K I think I could make the average category now.)
What activity class do you have in the Suunto software, that makes an enormous difference to how it uses the R-R and EPOC data to calculate a TE and other values.
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. Maximum measured HR is 188 about what it should be for my age (35) - and spending 52 minutes at 85-95% of one's maximum heart rate is still a significant workout at any activity class level. The EPOC actually seems more directly related to HR, HRV than activity class - but the TE clearly requires different attainments and durations of EPOC levels depending on activity level.

Also the paces you've give (even for an unfit lady) tend to point to technique issues.
My technique isn't bad (according to those who have observed) - although it certainly could be better. That's why slow rows focusing on technique are still beneficial to me. I just started rowing last August. I more often have has to slow down because of musculoskeletal issues than because of aerobic capacity limitations. The problem with rowing is that the faster one rows, the more resistance - so sometimes slowing down is my only option if I want to keep rowing without hurting myself. (DF is already at 1.) Also initially, when trying to go fast my technique would deteriorate - but this is much less of a problem now than it was. After over a million meters - I hope it's not too much of a stretch to think of myself as at least somewhat fit rather than unfit. ;)

I agree with Iain in that I don't think the paces in the forums reflect the full range for all fitness levels and classes of people. I got an inkling of this when I convinced a friend of mine to do more rowing and she was a lot slower than me (she's also a lot smaller than me.) That's why I found the HR monitor useful in giving me a better idea of the intensity of my workouts. I still benefit from slow rows focusing more on technique and using the right muscles - but I thought adding the H.R. monitor would help me make sure I'm getting some aerobic benefit.

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Post by jamesg » April 6th, 2009, 4:38 am

I don't think the paces in the forums reflect the full range for all fitness levels and classes of people.
They certainly don't. Most people on the forum have been rowing for years. The difference in fitness to those who do nothing is enormous.
With six months rowing under our belts, we can all consider ourselves in the 1% fittest on the planet.. so long as we pull reasonably hard with all the muscle available.
As to indices, HR tells us we're working in a training band and getting the aerobic benefit, W/kg our intensity level, Watts/rating our stroke quality nd technique; and when we end the piece, litres of sweat confirms it all. After those six months, it's the skin on our hands.
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