slides?

[johnlvs2run]

John: if you are 3 sec faster then it is probably your technique that is perfectible!

Thank you!

It's .5 spm for 2 seconds, i.e. the same meters per stroke.

[johnlvs2run]

I compliment you on being a much better rower than I am, and I'd suggest much better than most of the people on this board - the first time I used them I kept bouncing off the ends, losing my timing, and generally getting a very good aerobic workout with a very poor split.

Cheers, Paul

Thanks, Paul.

Maybe I just have rowed more.

Anyway have you checked to make sure each slide is level?

When they are level, it is very difficult to click on the ends of them.

[Chad Williams]

It looks like it has nothing to do with "able" (like you) or "incapable" (like me, as you insinuate)

Mark, you are very insecure. If you had a positive metal attitude, that would help you in a lot of ways.

[PaulH]

John - As I said earlier, I've only tried them once or twice in a gym. I had no doubt that I could get used to them pretty quickly, but the thought of hopping on and comfortably beating my PBs immediately amazes me.

Cheers, Paul

[mpukita]

It looks like it has nothing to do with "able" (like you) or "incapable" (like me, as you insinuate)

Mark, you are very insecure. If you had a positive metal attitude, that would help you in a lot of ways.

Chad, I will give you this, you do make me smile ... which is a good thing BTW ...

When we meet, and we will if you race at any or all of Evesham, BIRC, EIRC, or CRASH-B this year, you'll realize how funny this post really is ...



I'm just here for the beer ...

[Chad Williams]

I want to shake you by your hand and BiRC Mark (or is it neck)

You also make me laugh.

[mpukita]

Whatever ... hand, neck ... just keep your hands off my wallet, watch, and private parts and we'll do just fine!

[ancho]

It is out there, go and find it like I did.

It was based on 16 water rowers, all different weights, heights and abilities, they where tested on slides and then off slides, then reversed, slides then static erg.

"In summery, the best performance increase was in the heavier individuals, improvements of between 3%-5%, in the lighter categories (male and female) the performance (making allowances for fatigue) was negative."

Not very helpful at the beginning, but getting better towards the end.
I kinda like the new atmosphere generating around here...
Chad shaking necks with Mpukita, great!
Keep it on!

[ancho]

I've had several goes on RowPerfect, and the feeling is quite different, it makes you push more with your legs and less with the upper body.
RowPerfect idea is superb, general finish is much better on C2.

How do you like the RowPerfect?

I like it very... strange!
Haven't rowed it enough to have a clear idea. The feeling is just it gets much more from your legs, and less from the upper body.
And it's not near as robust as a C2, so there is a subjective (and absurd) "insecurity" feeling.
C2 sound is better as well!
I've also rowed with my crew mate in 2 RowPerfects linked in parallel, which is great fun!

[PaulS]

Thanks Mark for your valuable feedback!

Regarding efficiency, Paul Smith (an able rower IMO) has done some tests that show that to generate the same watts on slides, one has to increase the stroke rate by about 1.5 spm (if I remember correctly). He concluded that if anything, slides are slightly disadvantageous for someone with good technique. Please Paul, correct me if I am wrong!

Xeno Muller (another able rower!) likes them alot.

Not exactly. All of the scientific evidence I have seen has shown no particular difference between being on or off slides, and it appeared that there may even be a slight disadvantage as far as energy consumption goes when on the slides, inasmuch as that can be determined by HR monitoring.

My own view is that ALL the indicated advantage (read 'displayed pace on the PM') has to do with the associated increase in stroke rate, i.e. The DRIVE was no more powerful, but the stroke time became shorter and this decreases the value of the denominator in the Power Formula (watts=joules/sec) which is converted to PACE. So it's basically 'gaming the PM', but it can't continue for very long periods of time at anywhere near maximal effort. Maybe for a 100m time trial, but certainly not for a 2k. A person might do better on a long distance, since they would not be pushing the limit of their system, by definition. Perhaps a psychological factor of 'thinking there is an advantage' would come into play.

Slides do tend to punish some technical errors less than being on a grounded Ergo, especially problems associated with higher stroke rates and having to burn energy reversing the bodies momentum at the catch which then cannot be used to spin the flywheel.

As for the "Able Rower" argument, it appears that Chad's Study (which I have not seen, but would be happy to review) could easily be explained by what has been known for a long time; "lwt rowers tend to be more technically adept than their hwt counterparts." (Though if techique/fitness are equal the hwt always wins, both on the Erg and on the water.) So while it might appear that the 'advantage' is determined by weight, it is actually determined by skill. i.e. A technically good hwt will show no advantage, just as a technically good lwt; and if both are not technically good, both will show a relative advantage as the slides punish the flaw less than the grounded Erg. The lwt will be 'punished' less on the grounded Erg because they have less body mass to cause problems with. Thus the lwt that sees a big advantage on the Slides is likey to have very dodgy technique, as they manage to cause themselves problems in spite of having little body mass to do so.

The difference in force profiles between the grounded and Erg on slides is a way of illustrating the underlying technical flaws, IMO. Minimize those differences and you are well on your way to having a solid technique. Notice I don't specify the particulars of the "optimal profile" since this will vary by coach, and it allows for those differing views to be supported by the "Slides Vs Grouded Erg" profile indications. Just as ErgMonitor can give feedback on a "well coordinated stroke" regardless of the exact shape of the profile.

Summary:
Power production is power production, we input energy on the drive and then recover in a way that makes the entire stroke efficient or not. We can not magically produce more drive input by putting the Erg on slides, but some may be able to produce "less input at a greater rate" which will display a faster pace, just as a crew hopes to bring the rate up and advance their boat more quickly in the final sprint, though sometimes just the opposite occurs simply due to inefficiencies in the whole system, which is different from an Erg on Slides which has no drag penalty as a boat does.

[johnlvs2run]

To sum it up, slides are faster by 3 to 6 seconds for heavyweights per 500 meters.

[PaulH]

The problem with summing something up when you're wrong, John, is that the summing makes you more wrong.

For example - if I weigh 166lbs then I'll be 3-6 seconds faster, but if I lose 2lbs I'll suddenly be no faster, and perhaps even slower? But if I magically become a woman, I'm suddenly 3-6 seconds faster again?

Cheers, Paul

[arakawa]

Everything I've seen published says there is no advantage that can be determined scientifically. Yet, many post this as if it's fact. Maybe it is and I've just missed the results from the study or studies.

I've posted this link to a comparison of dynamic ergs (i.e. ergs that are allowed to slide back and forth, like the RowPerfect or a C2 erg on slides) and static ergs (e.g. a C2 erg on the floor) in the old forum. I don't recall if people commented on the validity of the analysis. My only complaint about the analysis is that it doesn't consider the recovery (if you're strapped in, chances are you're pulling yourself forward, and that's not energetically free).

If we accept this analysis as correct, then

• Rowing on a dynamic erg at a specific pace and stroke rate takes less energy than rowing at the same pace and stroke rate on a static erg. If I have a stroke rate of 30 SPM, which is equivalent to half a stroke per second, and I expend 20 joules more per stroke on a static erg than I would on a dynamic erg, then I have to generate 10 watts more to maintain the same pace on the static erg.
• The extra energy a rower must expend on a static erg (as opposed to a dynamic erg) is directly proportional to his/her mass. If two people of identical drive length (reasonably approximated by height or leg length) and drive duration (reasonably approximated by stroke rate) but with one person weighing twice as much as the other, the heavier person gets approximately twice the energy advantage while maintaining the same pace on the dynamic erg (presumably the person weighing twice as much doesn't have an erg that weighs twice as much - if the heavier person did have an erg that was twice as heavy, then the energy advantage would be exactly a factor of two).
• The power advantage on a dynamic erg is approximately proportional to the square of the stroke rate. Assume that the ratio of drive to recovery is independent of stroke rate. Then, if you double your stroke rate, your drive time (the variable t in the analysis) is halved, thus doubling the energy advantage per stroke. But, because you doubled your stroke rate, you're enjoying this per stroke energy advantage twice as often. Let's say, at a stroke rate of 20 SPM, I'm saving 16 joules per stroke on a dynamic erg. If I double my stroke rate to 40 SPM and keep my drive to recovery ratio constant, then my drive time is halved and I'm saving 32 joules per stroke. At a stroke rate of 20 SPM, I'm saving 320 joules per minute or 5.3 W. At a stroke rate of 40 SPM, I'm saving 1280 joules per minute or 21.3 W, which is four times 5.3 W.

I think that it should be noted that this analysis makes no allowances for differences in rowing style between the dynamic erg and the static erg, and so we must therefore assume that technique (however that might be defined) is identical in the two cases.

The analysis and my conclusions conflict with other people's statements; I welcome critiques of both (although I am not the author of the analysis).

In the grander scheme of things, perhaps we should consider the use of slides just another tool to help people either simulate rowing on the water or getting better at rowing on the water, as it "feels" more like rowing on the water, independent of the extent to which the use of slides might affect one's performance on the erg. After all, we are all aware of how the erg does nothing to each people how to handle an oar in the water as well as how many people use stroke techniques that may produce better times but would never work on the water, but we all still use the erg.

[johnlvs2run]

The problem with summing something up when you're wrong, John, is that the summing makes you more wrong.

Thank you for giving an example of that, Paul.

By heavyweights I am referring to those who are 200 to 250 pounds or so.

Many women are around 100 to 110 pounds so, no, they would not be automatically considered to be 250 pound male heavyweights. Lightweight for women is 135 pounds or less.

The slide advantage increases, as the difference between the weight of the rower and the rowing machine likewise increases.

[johnlvs2run]

Assume that the ratio of drive to recovery is independent of stroke rate. Then, if you double your stroke rate, your drive time (the variable t in the analysis) is halved, thus doubling the energy advantage per stroke. But, because you doubled your stroke rate, you're enjoying this per stroke energy advantage twice as often.

I agree with your summary with the exception that if the ratio of drive to recovery stays the same, then your energy advantage is the same, not doubled, i.e. there is no energy advantage from increasing your stroke rate.

The advantage is simply that, as the slides are faster, you can go a faster speed on them, while keeping your stroke rate proportional to your speed, and proportional to your meters per stroke.