Originally Posted by Zenturtle
Ok, we cut the treetrunc into slices, drill a hole in the center and stick a rod through the hole to keep everyting aligned. Al the slices are connected with muscles (the core muscles).
On top of that we give it 2 wooden legs which have the same degree of freedom as a human leg.
So all the parts between shoulders and toes are free to rotate in an organised manner now.
What would be the optimal internal action between toes and end of tree to help its forward movement in the water compared to the stiff treetrunc with stiff wooden legs?
Or in other words, what is the essence of hipdrive without bending and without kicking?
I don't think you have the right question, so I'll modify it a little bit and see if you can live with my changes. Don't just cut the tree trunk in slices, but also cut it parallel to its axis through the middle, so you can now slide the halves forward and backward with respect to each other. This is what happens when you reach forward with your extended arm and your hips on the same side move with respect to your hips on the other side. Now you can rotate the slices with respect to each other, but you can also slide them back and forth. But you have to keep everything absolutely straight. Now what is the optimal action?
I haven't the faintest idea, but at least now the question makes sense to me as a swimming analogue. I suspect that the answer also depends on the range of motion of your shoulder and hip joints, but I don't know this.