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
Steve,
The key phrase in your analysis is 'if the drag forces remain constant'. In swimming, they don't. Far from it. The difference between the drag coefficients in water with the hand-in-front, outstretched position (other hand releasing) (relatively streamlined) and the arm-sticking-straight out position when hand is at chin or shoulder (very unstreamlined) is off the charts.
Taking an armstroke in freestyle is like streamlining, then throwing a parachute out the back, then cutting the cord to it and back to streamlining again...that occurs with each arm pull. That is why we decelerate into that horrible arm-out position in spite of a significant force being applied up front.
To appreciate the drag forces we are dealing with when our hand is at our shoulder underwater, try kicking fast with fins on with one arm over your head and the other sticking straight down. You will see what I mean about the parachute.
What makes swimming complicated to analyze is that we have significant changes in power from front end to back end of the pull with even more significant changes in drag occurring simultaneously. Now, throw in the propulsive and drag forces of a six beat kick and you have one complicated mess.
Yours in swimmming,
Gary Sr.
Steve,
The key phrase in your analysis is 'if the drag forces remain constant'. In swimming, they don't. Far from it. The difference between the drag coefficients in water with the hand-in-front, outstretched position (other hand releasing) (relatively streamlined) and the arm-sticking-straight out position when hand is at chin or shoulder (very unstreamlined) is off the charts.
Taking an armstroke in freestyle is like streamlining, then throwing a parachute out the back, then cutting the cord to it and back to streamlining again...that occurs with each arm pull. That is why we decelerate into that horrible arm-out position in spite of a significant force being applied up front.
To appreciate the drag forces we are dealing with when our hand is at our shoulder underwater, try kicking fast with fins on with one arm over your head and the other sticking straight down. You will see what I mean about the parachute.
What makes swimming complicated to analyze is that we have significant changes in power from front end to back end of the pull with even more significant changes in drag occurring simultaneously. Now, throw in the propulsive and drag forces of a six beat kick and you have one complicated mess.
Yours in swimmming,
Gary Sr.
