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.
Former Member
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'd be tempted to say that the reason why your fastest point in th estroke cycle be when hand first enters the water, is that whilst this is occuring, the other hand has just finished its job, that is ensuring the the peak power occurs near the end of the stroke.
Peak power during the pulling path in Free Style occurs by the second half of the pulling.
Gary, there's one very simple way to experiment and measure this: Swim with one arm only!!
Also consider that, if we're doing it right, our stroke is getting a little bit of help from lift, which is actually moving our hand forward. If not, then the hand stays put (fooling around with drag) while our arm changes position indicating continuously how far our body has moved forward.
Also consider that, if we're doing it right, our stroke is getting a little bit of help from lift, which is actually moving our hand forward.
I disagree. Lift is a component of force perpendicular to the mean flow. Since we're moving forward in the water, lift can only affect our body position, not move us forward. The only thing moving us forward is a propulsive force with a forward compnent caused by the arms and legs reacting against the water.
The power forces of the hand change from almost pure lift in the outstretched position, to nearly pure propulsive drag when the hand is about at the shoulder level. The motion of the hand is in nearly a perfect circle of about 2 feet. It moves forward, down, then back, up and forward again, leaving almost exactly where it started. In between these points at the top of the circle (pure lift, moving forward) and the bottom (pure drag, moving backward), there are vectors of force for both lift and propulsion occurring simultaneously. Lift likely has the effect of increasing our velocity by reducing drag, if we have any significant propulsion with our legs. It turns out, understandably, that the best hold-out-in-front, lift swimmers have the best kicks (Thorpe, Phelps, Hackett, Lezak etc). Out front, they are generating lift not just from the hand, but from the entire arm. Also, the more speed they can generate while holding out in front, the more lift...just like a plane taking off down the runway.
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.
Where's that physics prof? His presence would be a bonus, but all that has been throughly studied, analyzed and described since 1980 by Ernest Maglischo.
And again, to better guess when the power occur just perform one-arm freestyle. It then becomes clear.
Does lift in the stroke keep you higher in the water creating less drag?
Or does the added "surface turbulence" just slow you down?
I have no hard numbers to compare, but my Early "Nearly" Vertical Forearm stroke has evolved to my elbows barely below the water surface .....with the forearm at about 5 - 10 deg. to perpendicular to the bottom.....creating some lift. I will concentrate on perpendicular (no lift)to see what outcome.
Georgio :bolt: :bliss::argue:
I disagree. Lift is a component of force perpendicular to the mean flow. Since we're moving forward in the water, lift can only affect our body position, not move us forward. The only thing moving us forward is a propulsive force with a forward compnent caused by the arms and legs reacting against the water.
Kirk,you are right about the direction,but the key is the hands,not the body. When the hands generate lift it is because they are moving side to side relative to the body(the old S stroke idea) and that "anchors" the hand allowing it to be used for thrust.Sculling is lift generated propulsion.It works,just evidently not as well for freestyle as the more drag dominant EVF pulls currently in vogue.
I disagree. Lift is a component of force perpendicular to the mean flow. Since we're moving forward in the water, lift can only affect our body position, not move us forward. The only thing moving us forward is a propulsive force with a forward compnent caused by the arms and legs reacting against the water.
Whether lift or drag, propulsion occurs when the forces pair up, and lift indeed is a propusive force that pulls my hand forward. Now that kind of assistance I'll accept gladly.
