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.
It sure is counterintuitive that we're actually decelerating at precisely the time when we're applying the most force to the water. I guess the fact is we've got to live with this deceleration to get the acceleration at the point that propulsive force outweighs the drag.
This got me thinking about rowing. You know how in rowing races you can see the shells in neighboring lanes surge ahead slightly or fall back based on when they are stroking? I guess I always assumed the "surging ahead" was happening when those rowers were stroking, but go watch a video and you'll see it's just like in swimming: the boat actually decelerates the instant the oars go into the water. It's obvious when you think about it. It's like putting on the brakes until the rowers are able to overcome all that drag caused by the oars. The boats probably start to accelerate somewhere around the point where the oars are perpendicular to the shell.
For swimming it certainly makes you wonder if there is some way we can stroke that will reduce that drag up front without sacrificing the power.
It sure is counterintuitive that we're actually decelerating at precisely the time when we're applying the most force to the water. I guess the fact is we've got to live with this deceleration to get the acceleration at the point that propulsive force outweighs the drag.
This got me thinking about rowing. You know how in rowing races you can see the shells in neighboring lanes surge ahead slightly or fall back based on when they are stroking? I guess I always assumed the "surging ahead" was happening when those rowers were stroking, but go watch a video and you'll see it's just like in swimming: the boat actually decelerates the instant the oars go into the water. It's obvious when you think about it. It's like putting on the brakes until the rowers are able to overcome all that drag caused by the oars. The boats probably start to accelerate somewhere around the point where the oars are perpendicular to the shell.
For swimming it certainly makes you wonder if there is some way we can stroke that will reduce that drag up front without sacrificing the power.
