Conventional and EVF can be one in the same unless a conventional swimming stroke means purposely dropping your elbow. The pulling pattern should never be straight back because the longer and the harder the hand moves backward the greater reduction in drag force (negative drag coefficient). The hand must move (scull slightly) into less turbulent water so peak drag force or pulling power can be maintained. As strong swimmers begin to improve their EVF, sprinters will begin to evolve into more right angled looking strokes like Rebecca Addlington's and less like Alain Bernard's. With everything being equal, a stroke like Bernards, in my opinion, can become faster by getting his forearm/hand vertical earlier. With that being said, Bernard may have anatomical factors (weak shoulder cuff, flexibility issues, EVF strength conversion habit issues) that could prevent that EVF alteration (his coach knows best). My contention is that any swimmer who can, without compromising anatomical health, improve the length of time they can keep their hand/forearm in the vertical position and improve how early they can get their hand / forearm in a vertical position, will drop time. I think conventional (as long as it doesn’t mean purposely dropping your elbow) and EVF are the same and physical limitations and training habits create the variances from swimmer to swimmer. The fastest swimmers in the world may have different looking strokes but the winners keep their hands/forearm in the vertical position earlier and in a vertical position that produces the most power the longest. Getting your hand / forearm in a power position early and keeping it their longer, isn’t all about pulling strength, it’s more importantly about the ability to resist dropping one’s elbow. I started doing an exercise where swimmers kick 50 yards with fins, holding their arms in front of them (breathe to the side or in the front), holding an EVF position. Try it and it will show you the ability to “set-up” your stroke early (conventional or not) is more difficult than you can imagine. The pressure of simply swimming forward requires strong shoulder-cuff stabilizing muscles ( supraspinatus, infraspinatus, teres minor, and subscapularis) and the above exercise will show you how weak or strong yours are. I think it’s safe to say, more often than not, swimmers don’t have the necessary shoulder cuff strength that allows them to properly “set-up” their stroke. And, let’s think about it, if you can’t keep your arm in a “set-up” position (conventional or not) for 50 yards, what are the chances of ever developing a better “set-up position until you strengthen and train to improve the muscles responsible for that position. I think isometrics and the use of surgical tubing offers the most effective way to improve shoulder-cuff strength. Email me at tomtomp@netzero.com if you’re interested in more information. Good luck, Coach T.
Former Member
Let me simplify this a bit so we can get to the meat of the issue:
1) Let us say that you have grabbed an immovable bar with your hands so you have a stationary pivot point
2) Let us say you are swimming butterfly in order to keep things symmetrical
3) Let us say that your elbows can flex as needed so that your body can travel in a straight line forward as you pivot rather than in an arc.
It seems to me that you have a load, in this case the drag on your body that is acting backwards, i.e. pulling the lever in the opposite direction from that desired.
You have a muscle attached to your arm and to your trunk which again is pulling the arm in the wrong direction.
The only force I can see that is exerting a moment in the forward direction is the momentum/inertia of your body.
If this is the case then you cannot use the hand as a pivot.
You had suggested that in freestyle you can use the opposite shoulder to generate a moment around the pivot point but I don't see how you can push the lever forward.
If you use the shoulder joint as your pivot then you have muscles which can generate a moment in the desired direction around the shoulder joint, that creates a force at your hand, which the water returns providing forward propulsion.
Have I erred somewhere?
Also, when paddling a canoe one of your hands acts as a pivot, either you hold the lower hand stationary and push the top forward (1st class lever), or you hold the top stationary and pull back with the lower hand (3rd class lever), or a combination of the two, moving the pivot point between your hands.
First of all; whether you are swimming, rowing a shell, paddling a canoe or kayak; the water is the fulcrum for your 2nd class lever. The water is not the load. The load is your body, the shell, the canoe or kayak. The force comes from the top hand pushing forward on the canoe or kayak paddle, and the hands pulling back on the oar handles. The load is between the force and fulcrum, and moves in the direction of the force. That is why our body moves in the same direction as the outside/opposite shoulder (force) is moving when swimming. A third class lever would only result in the load moving backwards. Have you read Swimming Fastest? I am curious to hear about your opinion on chapters dealing on the various forces involves in human swimming propulsion?
No one has yet identified with certainty the way swimmers propel the body through the water. All we have are theories, and they have varied considerably through the years. Ernest W. Maglischo, 2003.
Just to add to what you're explaining, the reason Clyde may think that the hand doesn't move back, is that the entry and exit points are virtually at same location.
The detail that is overlooked though is that after entering, then hand travels forward quite a lot. Therefore it travels back to exit pretty close to entry point.
There may be a few theoreticians who still pick Lift as the main source of propulsion at all strokes, but I think the highest profiles have changed camp over the last few decades.
What I find particularly interesting nowadays though, is that when you speak to the swimmers themselves, those who are bloody fast I mean, most seem to have simplified the mental image of a good pulling path. Most describe it as being from point A straight back to point B. I had this chat with a very young future master fancying lowering the 200fly U2:00. Asked him recently, pull straight back, no fancy stuff, as simple as that.
So it seems the message went through quite nicely.
I suspect that Maglischo was shy about making definite statements after going through the whole lift forces debacle.
While swimming is complicated to analyze in detail we can experimentally determine many of the gross mechanisms. We can measure the drag forces on the body as a whole and we can measure the drag forces on individual limbs to determine their approximate contributions.
We know without a doubt that Bernoulli's principle doesn't apply to human hands and arms. We know that the vortex theory completely failed to look at the relative magnitudes of the forces postulated. We know that some really fast swimmers pull straight back, not using lift forces in their pull at all.
Hopefully we have learned that hypotheses should be tested before being published. Ok, I'm officially on a tirade. :blah:
Isn't it odd that "drowning" is the only swimming related smiley?
It's mildly amusing that messages I post show up in my inbox before the web page I submit them with changes.
And finally, there should be a law against posting videos like this one:
">www.videojug.com/.../how-to-swim-butterfly-stroke"
Especially if your domain name is swim-teach.com
Got timed out on the reply and unable to recover it so here goes a briefer one: I really enjoy all the different responses and yes I read his first book and many others a long time ago.
Anyway, regarding 3rd class levers, I belive the problem today is the way they are illustrated with the fulcrum incorrectly placed in the same position as a 2nd class lever. This is an error that has been repeated over and over for the past 50+ years, and caused so many erroneous opinions. Using a broom should demonstrate that the fulcrum should be placed on the opposing or opposite side of the lever or it will not work. A canoe paddle can be used as all three (3) levers, but only when used as a 2nd class lever will propel the canoe forward. As a 1st class lever, the fulcrum becomes the lower arm, and the load (water) travels in the opposite direction of the force (top hand). As a 3rd class lever, the fulcrum becomes the top hand, and the load (water) travels in the same direction of the force (bottom hand). Levers in anatomy are internal and should be kept separate from the action that's external.
Whether drag, lift, vortex shedding or axial flow, they all involve the action of forces that act in pairs. The trick is making a better marriage of them with EVF. clyde
A canoe paddle can be used as all three (3) levers, but only when used as a 2nd class lever will propel the canoe forward.
This is the crux of the matter. Consider the case of using the paddle as a 1st class lever, i.e. top hand pushing forward and bottom hand holding stationary. The top hand is placing a forward force on the paddle which generates a backward force against the water at the other end of the paddle. The water exerts an equal and opposite forward force on the paddle. The lower hand has to exert a backward force on the paddle equal to the sum of these two forward forces. That means the paddle is exerting an equal and opposite forward force on the lower hand, and it is this force that causes you and the boat to be propelled forward.
Performing a similar analysis on the case of a 3rd class lever is left as an exercise for the reader. :)
Exactly what happens when the water is the fulcrum (2nd class lever) and not the load. And why some swimmers are faster than others because they are moving themselves forward and not wasting energy moving water backwards. Reminds me of the textbook that shows a picture of a fisherman rowing a boat and incorrectly calling the oarlocks the fulcrum.
Exactly what happens when the water is the fulcrum (2nd class lever) and not the load. And why some swimmers are faster than others because they are moving themselves forward and not wasting energy moving water backwards. Reminds me of the textbook that shows a picture of a fisherman rowing a boat and incorrectly calling the oarlocks the fulcrum.
It's not actually possible to use a paddle as a 2nd class lever. The 2nd class lever scenario you are putting forth has the upper hand working as the force, pushing the end of the paddle forward, the lower hand working as the load, therefore pulling the middle of the paddle backward, and the bottom of the paddle acting as the fulcrum. This is actually a 1st class lever with the lower hand acting as the fulcrum. The water won't apply a net force on the paddle unless the paddle is moving through the water, in which case it doesn't meet the definition of a fulcrum as the paddle will be pivoting around the lower hand.
Consider a bar attached to a solid wall with a hinge, you are holding it with one hand at the end, and the other half way, the equivalent to what you are suggesting is that you could push the bar up with the hand at the end of the bar while hanging by the hand in the middle of the bar. This is clearly impossible because the sum of the forces you exert on the bar will always amount to the force of gravity on your mass.
So the text book was in fact correct, the oar locks are the fulcrum, i.e. the fixed point around which the oar will rotate.
