Concept2 and lower back pain

[Nosmo]

Try again: The question is about the movement of the hands period. You did not answer the question. Do the hands move horizontally or not?

Start there then we can go on to the rest of it.

The line of force is from the shoulders to the water.

Clearly we can not go on to the rest of it. You've been taking too many cues from Ranger. Perhaps the chemtrails have affected your brain.

[johnlvs2run]

John, you really aren't thinking about what you're saying. Which is what I drew in on that piss poor force-body diagram.

Paul, your diagram shows the line of force well. Thanks for sharing it.

To paraphrase Yoda: See, or do not. Thinking does not matter.

[johnlvs2run]

Clearly we can not go on to the rest of it.

There are none so blind as those who won't see.

[bloomp]

John,

if the net force was indeed in that direction, there would be acceleration in the opposite direction. Upwards, in the argument you're using. Yet the boat moves horizontally.

[snowleopard]

John,

Do you know what a punt is?

[peterhowd]

John - think teeter-totter. You push down on one end, and no matter how you do it, the other end goes up. It doesn't matter what contortions you might go through, if you push down with sufficient force, the other end goes up. Now, turn that on its side and you have an oar. As long as you move the oar handle MOL horizontally toward the bow, however you might do that, the blade will move toward the stern. Newton tells us that actions have equal and opposite reactions, so the boat moves forward. If the force was entirely vertical, as Paul diagrammed to make this point, the boat would bob up and down in place. Does this make any sense to you?

The oar isn't a force vector, it is a lever that transmits the rower-applied force at the handle, across a fulcrum, to the blade, giving an oppositely directed force at the blade. All the leg, hip, shoulder, elbow, hand and boat rigging angles are important to the magnitude of the force, but not so much the direction. Again, think teeter-totter. Not sure we can make it simpler than that.

[johnlvs2run]

if the net force was indeed in that direction, there would be acceleration in the opposite direction. Upwards, in the argument you're using. Yet the boat moves horizontally.

In that direction? Okay I see you are thinking of pressing the line of force downward.
What a crazy idea. The comparison on an erg would be to move the handle up and down.

Obviously, you move the line of force forward and backward, the same as on the erg.
I answered this question previously here. http://www.c2forum.com/viewtopic.php?p=128175#128175

Errrrrrr, if that were the case how does a boat move horizontally?

When the rower moves the line of force front to back, the boat goes the opposing direction.

The difference on the erg is that one end of the line of force is horizontal to the other.

In a boat otw, one end of the line of force is at the shoulders, and the other extends down under the water.

Big difference.

Hopefully everyone is able to see this now, as is obvious in all of the photos. Just look at the photos.

[bloomp]

John,

There are not two forces in one direction in either situation. There is the force of the rower on the erg handle, and the tension of the chain against the handle. That creates one vector. On the water, there is the force of the rower on the oar handle, and the force of the water against the oar (inertia).

What you seem to be suggesting is that the legs and shoulders create two different vectors for the force. But they don't, because the body acts as one unit. We cannot make ourselves move without having a reactionary force. We don't walk because we move, we walk because of the force of friction. The flywheel doesn't spin because our legs push, it spins because there is the tension of the cable. The same applies for OTW, there is no difference between the push of the legs and the pull of the arms.

When you pull in OTW (I am not sure how much OTW experience you have), it's identical to pulling in on the rower. There is zero difference. The fact that the force applied is distributed differently has nothing to do with the fact you are still applying the identical forces. Because you have a lever, however, it is that much more effective to pry your way through the water. The axle height is as it is because that's WHERE OTW rowers will maintain a steady handle height through the drive.

[johnlvs2run]

John - think teeter-totter. You push down on one end, and no matter how you do it, the other end goes up. It doesn't matter what contortions you might go through, if you push down with sufficient force, the other end goes up. Now, turn that on its side and you have an oar. As long as you move the oar handle MOL horizontally toward the bow, however you might do that, the blade will move toward the stern. Newton tells us that actions have equal and opposite reactions, so the boat moves forward.

A simple teeter totter would not work, as it would be entirely horizontal and have no contact with the water.

Now, put the fulcrum of the teeter totter on the edge of the boat on one side, pointed downward to the water,
the same on the other side, and you have a pair of oars, pointed downward to the water, not horizontally.

If the force was entirely vertical, as Paul diagrammed to make this point, the boat would bob up and down in place. Does this make any sense to you?

That would be a silly idea, except maybe as good as holding the oars out horizontally.

The oar isn't a force vector, it is a lever that transmits the rower-applied force at the handle, across a fulcrum, to the blade, giving an oppositely directed force at the blade. All the leg, hip, shoulder, elbow, hand and boat rigging angles are important to the magnitude of the force, but not so much the direction.

The rigging is important as it determines the line of force direction to the water.

think teeter-totter. Not sure we can make it simpler than that.

The photo is much better. Just look at the photo.

Anyone should be able to see the oars are in the water, and are not horizontal to the shoulders.

[johnlvs2run]

John,

There are not two forces in one direction in either situation. There is the force of the rower on the erg handle, and the tension of the chain against the handle. That creates one vector. On the water, there is the force of the rower on the oar handle, and the force of the water against the oar (inertia).

Extend those out, on the erg there is the tension from shoulders > hands > axle > almost horizontal.
On the water, there is the tension from the shoulders > hands > to under the water > most notably downward.

What you seem to be suggesting is

What I have said is what I am saying. Look at the photos.

The fact that the force applied is distributed differently has nothing to do with the fact you are still applying the identical forces.

The fact that the force is applied differently is exactly the issue.

The axle height is as it is because that's WHERE OTW rowers will maintain a steady handle height through the drive.

That is not so!

You cannot show even one photo of someone rowing in Olympics or World Champs with the line from the shoulders > arms > oars all being horizontal!

Because the oars would not be in the water and it would not be possible to make any progress.

It is not the same as the erg.

The line of force on the erg is completely different from the line of force when rowing otw.

[peterhowd]

I give up.

[Nosmo]

I give up.

That is the appropriate response. It is hopeless.

[Frihed89]

Getting back to the original question. I have a collapsed disk that was never operated on. It gives me great lower back discomfort in level walking in the city, but not climbing. Use of the Concept 2 45-50' minutes a day does not seem to have any beneficial or adverse effect on my back. However, I can not say what the baseline would look like without indoor rowing.