Friday, January 26, 2007

Static vs. Dynamic Ergs - Concept II Comments


Yesterday I posted the comments of Mark Campbell of Rowperfect on the FITD erg discussion, and today I have Dick Dreissigacker's of Concept II. If you recall, a paper by Ivan Hooper of Rowing Australia (and some FITD commentors), found fault with static ergs. (See the last post for links to the paper and FITD posts.) In short, the argument is that static ergs are more likely than dynamic ergs to cause injury because there is greater force applied at the catch and it promotes overcompression. Other problems relate to the way the erg is used. Critics also contend that a dynamic erg better simulates actual rowing. As the manufacturer of a static erg (although one which can be made dynamic through the use of slides), Concept II came out on the short end of the stick. For this reason I'm particularly happy to have Dick's comments.

As I did before, I'll simply quote most of the C2 email to avoid mis-stating anything or quoting it out of context (emphasis is mine). Dick began by saying:

I agree that volume of work and the intensity of forces applied by the athlete are critical to monitor. However, it seems that in this discussion comparing ergometer rowing (fixed and dynamic) and rowing on the water, the most important aspect is overlooked. The magnitude of the force and the “speed vs. force relationship” that an athlete is able to apply is largely adjustable by settings on the ergs or by rigging of the boat. In general I feel that rowing athletes choose to train on ergs with the damper setting (drag factor) set too high, creating a situation where they can generate high forces at slower speed of movement than in a boat. This is not generally a good idea, and I have spoken with a number of coaches who have their athletes row the erg in the “easiest” damper setting, so they train to move more quickly.

The effect of low stroke rating on the force felt by the erg rower is significant. The more time spent on the recovery the more the flywheel slows down. The slower the flywheel at the catch the heavier the feel - in other words the more force the rower will be able to generate. The same is true in rowing with a low rating in the boat. We completely agree with the point that coaches need to consider the risks involved with long rows at low rating.

Interestingly, there is a strong tendency to row the erg in dynamic mode at a higher rating, thereby effectively reducing the force (the flywheel doesn't slow down as much between strokes at higher ratings). This factor may account for much of the difference seen in stress/load/force on the rower between static and dynamic mode.

Dick goes on to discuss the difference between the static and dynamic mode. I recall watching rowers test on C2 slides shortly after they came out. Some rowers pulled better scores while others couldn't stop banging the stops and had to go back to a static erg. Everyone, and I do mean everyone, said that slides couldn't be used for real testing because it was easier (tell that to the stop bangers). Well, what Dick has to say next came as a surprise:
When the Slides first came out, we all thought it would be easier to get a better score on the dynamic erg for all the reasons that have been stated. However, it turns out that the scores are quite similar in most cases (except in the case of short pieces where the dynamic is clearly faster probably due to the higher stroke rates). Hagerman's VO2 measurements on many subjects showed this as well. The metabolic costs of the static and dynamic C2 erg were very similar although there were individual preferences for one type of erg or the other.
Next, Dick addresses a finding in the Rowing Biomechanics Newsletter that highlighted the difference in power application between the static erg and a boat:
We also need to remember that power is not the same thing as force. Regardless of what part of the body is generating the power, the whole body will feel the force. Everything is connected. For this reason, we need to be careful about how we interpret the legs/trunk/arms power percentages of 37%/41%/22% on the erg as compared to the 45%/37%/18% in the boat.

The loading (force)in a boat is even more complex since it involves many variables such as angles, blade design, outboard/inboard ratios, spread, overlap, boat speed, stroke rate, body mass movements, etc. Given this complexity, it seems very difficult to make any across-the-board statement that either rowing in a boat or rowing on an erg is either heavier or lighter than the other. On a related note, we have been working hard to convince coaches that they need to shorten their oars when using our Fat blades. This is because the blade is more effective at “holding” the water, and thus more force can be generated at the end of the handle. It is our opinion that the “effectiveness” of a blade should be maximized and that the “loading” of the athlete should be adjusted by rigging or overall length.

In conclusion, we would offer that coaches need to pay considerable attention to the total training load with respect to volume, intensity, and force. An increased awareness of the situations that create the high stress/load/force situations, both off and on the water, will help the coach manage the training of their athletes.
So now, how to make sense of all this? Well, I think Concept II clearly recognizes the issues raised in the Hooper paper. C2 addresses the greater force at the catch problem by stressing that too many athletes erg with their settings too high. Dick talked about coaches who have their crews erg with the damper at the lowest setting. He didn't say if they were men or women, but think about what setting your team uses. It would certainly seem that lightweight women would have their damper the lowest of all. The feel issue (at least in terms of loading) is also addressed through a discussion of settings, both on the erg and in a boat.

I understand the point C2 makes with the settings, but I think it's a bit problematic. I think most rowers believe that they will pull their best scores at a damper setting other than 1. They'll erg at 1 if forced, but if push comes to shove, when trying for their best score, they'll move it up. Perhaps we can all be trained to race at 1, but it will take some time. Given that the erg is still static, however, it seems that the lower damper will only mitigate the problem, not solve it. Finally, I'm not sure how the feel can ever be the same as a boat on a static erg.

Erg selection aside, however, the most important thing I took away from Dick Dreissigacker's comments is that we're all likely rowing with too much load - on erg or in boat. If his general advice is to lower the damper and shorten the oars, it seems extra important for lightweight women to have those settings correct. I believe I've heard of more injuries than usual this year and I have to wonder if overloading isn't the culprit.

Now that you've read both responses, please let's hear your comments. If you look at the comments to yesterday's post, you'll see that Xeno Muller left his thoughts. He disclosed that he has a vested interest in the success of Rowperfect, but then again, as an Olympic gold medal winner his opinion should be worth something.

1 comment:

XENO said...

Hello
There is no doubt in my mind, that to teach, improve rowing technique and power it is imperative to use the dynamic indoor rowing machine system. Within a short time we FINALLY will have two choices. One is the C2 with slides or the Rowperfect. The cool thing about the Rowperfect is that you can directly put in your own weight and your "speed" is then the result of your power and your current weight.
In the case of the Iron Oarsman, our rowing studio here in Costa Mesa, it is crucial for me to be able to fit more rowing machines on my square footage. The Rowperfect requires roughly HALF the amount of surface than the C2 with slides. The potential of using the Rowperfect in gym multi purpose rooms is tremendous. From an indoor rowing exercise point of view, I could care less whether the C2 and slides is heavier than the Rowperfect. The most important for the success of an indoor rowing studio is that people get to row on a D Y N A M I C machine. In addition rowing the dynamic system gives the opportunity to row with one leg at a time that truely shows off the PUSH before the PULL specific to efficient rowing. There is also the REHAB or during injury training ability where in some cases, ankel, knee, or hip joint is hurt, by leaving that leg on the ground a "full" body exercise is still possible.
Good job Fightindog for giving us the opportunity to discuss better and healthier forms of training.
Over and out for now.
XENO