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
The major contributor to drag (pressure drag) during the underwater pull is the upper part of our arm. That part of the arm is moving forward at all times, while the hand has a net zero velocity (forward at the beginning, backward, then forward again) and contributes little to forward drag.
What is very interesting is that positioning the arm straight down creates a larger drag coefficient than the arm positioned out to the side. That is why all great swimmers use high elbows....not for more power or surface area, but for decreased drag.
You can test this yourself by kicking 25 meters all out with fins, first with the arm positioned straight down (other arm in front) and then by bending the arm at 90 degrees to your side. Both contribute to a large drag (you will feel it!) but much more with the arm straight down.
I was amazed at how quickly we go from the fastest positon to the slowest position (a few tenths of a second) strictly based on these long arms of ours. Poor engineering for moving fast in the water, but we have to deal with the cards we are dealt.
Gary Sr.
The major contributor to drag (pressure drag) during the underwater pull is the upper part of our arm. That part of the arm is moving forward at all times, while the hand has a net zero velocity (forward at the beginning, backward, then forward again) and contributes little to forward drag.
What is very interesting is that positioning the arm straight down creates a larger drag coefficient than the arm positioned out to the side. That is why all great swimmers use high elbows....not for more power or surface area, but for decreased drag.
You can test this yourself by kicking 25 meters all out with fins, first with the arm positioned straight down (other arm in front) and then by bending the arm at 90 degrees to your side. Both contribute to a large drag (you will feel it!) but much more with the arm straight down.
I was amazed at how quickly we go from the fastest positon to the slowest position (a few tenths of a second) strictly based on these long arms of ours. Poor engineering for moving fast in the water, but we have to deal with the cards we are dealt.
Gary Sr.
