A while back, I jumped on the triathlon website Slowtwitch and got attacked for saying that the power in the freestyle pull comes in the front of the stroke (hand entry to shoulder), not in the middle (shoulder to belly button) or back (belly button to release). Nonsense...they said. Didn't you read the article by Popov's coach showing the power is at the end of the stroke?
That never made sense to me. After all, at the end of the stroke there is only about one muscle still working, the tricep, and the hand is not in that position for very long.
At last, I got the proof I needed. A few weeks ago I was tested on the Velocity Meter, a very cool device that measures the speed of the body through the entire stroke cycle. It was VERY revealing and provided tons of information I could not get elsewhere.
Such as:1) the body speed slows by as much as 40% from the fastest to the slowest point during a single arm stroke. 40%!!! That is huge. The difference in speed is directly caused by the body going from a relative streamlined position to a very non-streamlined position and back again.
2) The fastest point in the stroke cycle is when the hand first enters the water and the slowest point is when the hand is about at the shoulder underwater. That is when the upper arm is pointing nearly perpendicular to the line of the body (ie most drag).
I realize that the speed of the body at any given instant is a result of the propulsive power minus the drag forces, that one cannot determine just from the velocity that the power is really greater in front. But when the speed drops from 2.5 meters per second when the hand is in front to 1.4 meters per second when it is in the middle, I have to believe that the power in front is greatest.
By the way, the propulsive power of the arm is created by both lift forces at the beginning and drag forces in the middle, as the hand shifts from forward motion to backward motion (then forward again as it releases).
Anyway, read my latest blog on our website www.theraceclub.com to find out more revealing secrets from the Velocity Meter.
Gary Sr.
Parents
Former Member
Dear Tomtopo,
I have not seen the research from the Olympic Training Center, but I can tell you that one cannot determine power by knowing what the velocity, acceleration or deceleration is at any given moment in the stroke cycle. The reason is that one can accelerate (or decelerate) by either a change in propulsive power or a change in resistive drag or a combination of both. Most objects we study in motion do not change shape, but the motion of the human body swimming freestyle is complicated by both changes in propulsive power and drastic changes in shape, significantly increasing pressure drag, as the arm moves through the underwater cycle.
Although there is deceleration (40% loss of speed) of the body from its fastest point in the cycle (with arm outstretched and other arm preparing to release) to its slowest point (with upper arm nearly perpendicular to the body line, hand about at the chin), I submit that this deceleration or loss of speed is not due to reduction of power but rather to a huge increase in drag force.
Anatomically, it makes no sense to say we have no power in front when virtually all of the muscle groups are working. By the time we release the hand, very few muscles are left working (tricep?). The power generated is also influenced by the counter-rotation of the hips (core), creating a counter force against which we pull, which is initiated with the catch and continues during the entire underwater pull.
The strongest argument one can make for believing there is significant power in the front quadrant is that we spend half of our cycle time in that front area. The other half is spent in the back quadrant and the complete over water recovery....ie hurrying to get our arm/hand back out in front again. If we weren't getting power there, I don't think we'd be spending so much time up there.
Gary Sr.
Dear Tomtopo,
I have not seen the research from the Olympic Training Center, but I can tell you that one cannot determine power by knowing what the velocity, acceleration or deceleration is at any given moment in the stroke cycle. The reason is that one can accelerate (or decelerate) by either a change in propulsive power or a change in resistive drag or a combination of both. Most objects we study in motion do not change shape, but the motion of the human body swimming freestyle is complicated by both changes in propulsive power and drastic changes in shape, significantly increasing pressure drag, as the arm moves through the underwater cycle.
Although there is deceleration (40% loss of speed) of the body from its fastest point in the cycle (with arm outstretched and other arm preparing to release) to its slowest point (with upper arm nearly perpendicular to the body line, hand about at the chin), I submit that this deceleration or loss of speed is not due to reduction of power but rather to a huge increase in drag force.
Anatomically, it makes no sense to say we have no power in front when virtually all of the muscle groups are working. By the time we release the hand, very few muscles are left working (tricep?). The power generated is also influenced by the counter-rotation of the hips (core), creating a counter force against which we pull, which is initiated with the catch and continues during the entire underwater pull.
The strongest argument one can make for believing there is significant power in the front quadrant is that we spend half of our cycle time in that front area. The other half is spent in the back quadrant and the complete over water recovery....ie hurrying to get our arm/hand back out in front again. If we weren't getting power there, I don't think we'd be spending so much time up there.
Gary Sr.
