My freestyle technique, what needs work?

Wow...some very introspective thought from the last post. This is why I enjoy posting some of our findings on a public forum like this because all of our work for the last 20 years has gone through extensive peer review by some of the best in the business, and I enjoy the feedback. I actually have forwarded your post to one of my aerospace engineer alumni to evaluate your comments. I believe all the comments you mentioned can be measured with our technology. Just a matter of getting to the right equations. Let me try to answer some of your observations that we have tried to examine. if you have a swimmer push off in a streamline, and then push off and start kicking immediately you should be able to get a handle on how much propulsion the kick provides at different velocities. How much propulsion the kick provides has been a hot topic for many years and I think you have the tools to answer it. At least for a given swimmer's kick. Have you done any testing along these lines? We have conducted extensive testing doing exactly what you described above, and in general terms here is what we found. Starting with push and glide from the wall, you get an exponential velocity deceleration curve like the one you posted earlier of my swimmer. When you push and flutter kick immediately it also produces an exponential deceleration curve with small “bumps” of acceleration and deceleration variance. The variations in the telemetry are caused by the opening and closing of the feet/legs. However, when you fit a mean line though the push and kick telemetry, and plot it against the push and glide line, they plot right on top of each other. (No difference) Again, I think you assume kicking from the wall provides propulsion that would create a deceleration curve that would be greater than the push and glide curve, but the act of separating the feet/legs creates drag, and the net effect is the same deceleration curve. Generally the curves separate somewhere around the 1.5 meters/sec point, where the push and glide curve continues down exponentially, and the push with kick velocity starts to level off. Again referring to thousands of push off and glide verses push off and kick trials, the push with flutter kick rarely ever produces a deceleration curve line that is better than the push and glide line, until you get to really slow velocities, not associated with regular swimming speeds. In addition, for most of the swimmers we have tested using the push and dolphin kick immediately from the wall typically produces a line that is slower than push and glide or the push and flutter kick to somewhere around 1.5 meters/sec. because most swimmers are really not as good at the dolphin technique as they think, and stay underwater to long and breakout well below their regular swimming velocity. But for that particular application, our technology can specifically define that intersection precisely without guesswork. Would I be correct that your values for acceleration, power, and force are derived from the velocity data? If so, the force would be net force (propulsive - resistant drag) on the swimmer rather than propulsive force?They are derived from the velocity data, and at this time, I would agree with you, because our values from the velocity meter were slightly higher than the hand sensors. That is why on the post, I used the values from the hand sensors and not the Velocity Meter. I also assume that the Aquanex measures pressure rather than force, i.e. it doesn't tell you what direction the force is in, and the pressure has to be multiplied by the surface area to determine the total force? If so, someone with a windmill style pull might be exerting force near the top of the stroke but much of that force would be downward and not be contributing to forward propulsion.I believe from the synchronized video, we can make some assumptions about the direction of the force/pressure through any part of the stroke cycle, and we have developed a very effective method of demonstrating that effect. The force telemetry I have seen with freestyle up to this point shows max force or pressure as you call it, occurred in general terms somewhere under the shoulder. To date, I have not seen any telemetry where the max force/pressure value for a stroke cycle occurring anywhere during the initial phase of a stroke cycle for freestyle. And if our comparable numbers are anywhere close to correct 20 to 30 something pounds of propulsive force does not seem very high to me, but as I said earlier, may be those are high numbers for free swimming. Also, when dealing with pressure the total force is proportional to the surface area (actually projected backward facing surface area would be the effective area) so someone with a bigger arm (or better oriented arm) could exert a larger propulsive force than a smaller arm (or less well oriented arm) even though the pressure they are generating is smaller.This is where I think we differ. When you speak about how one person could produce more or less propulsive force, what I think you leave out is during the stroke cycle as propulsive force is progressively being generated to its peak during a stroke cycle, what is also concurrently happening with the instantaneous velocity of swimmer? I believe I have already given you evidence to the answer of that question. It seems to me that the velocity meter inherently measures net force so you need something more to tease apart propulsive and resisting drag forces. The pressure sensor helps in this regard but requires effective surface area to determine propulsive force. Video data taken from the front could help determine area, although an outline taken from the front angle and combined with out of the water measurements could do the trick at the expense of a lot of calculations, although I guess computers can take care of those.At this time, the Velocity Meter could be measuring net force, and more work needs to be done in this area. This was the first time where two devices collected telemetry at the same time, so it's never good to jump to any conclusions without careful review, but the initial results were encouraging. Obviously these kind of measurements are not as easy like with other sports because the physics of moving through the water are not analogous to movements or measurements on dry land. Have you tried attaching the pressure sensor to the upper arm to see how much drag pressure there is there? That would give some very informative data with regard to your drag hypothesis.Not yet, the first step was to see how close those aerospace engineering alumni of mine could come up with equations that would output values from the Velocity Meter close to the hand sensors telemetry.

Wow...some very introspective thought from the last post. This is why I enjoy posting some of our findings on a public forum like this because all of our work for the last 20 years has gone through extensive peer review by some of the best in the business, and I enjoy the feedback. I actually have forwarded your post to one of my aerospace engineer alumni to evaluate your comments. I believe all the comments you mentioned can be measured with our technology. Just a matter of getting to the right equations. Let me try to answer some of your observations that we have tried to examine. if you have a swimmer push off in a streamline, and then push off and start kicking immediately you should be able to get a handle on how much propulsion the kick provides at different velocities. How much propulsion the kick provides has been a hot topic for many years and I think you have the tools to answer it. At least for a given swimmer's kick. Have you done any testing along these lines? We have conducted extensive testing doing exactly what you described above, and in general terms here is what we found. Starting with push and glide from the wall, you get an exponential velocity deceleration curve like the one you posted earlier of my swimmer. When you push and flutter kick immediately it also produces an exponential deceleration curve with small “bumps” of acceleration and deceleration variance. The variations in the telemetry are caused by the opening and closing of the feet/legs. However, when you fit a mean line though the push and kick telemetry, and plot it against the push and glide line, they plot right on top of each other. (No difference) Again, I think you assume kicking from the wall provides propulsion that would create a deceleration curve that would be greater than the push and glide curve, but the act of separating the feet/legs creates drag, and the net effect is the same deceleration curve. Generally the curves separate somewhere around the 1.5 meters/sec point, where the push and glide curve continues down exponentially, and the push with kick velocity starts to level off. Again referring to thousands of push off and glide verses push off and kick trials, the push with flutter kick rarely ever produces a deceleration curve line that is better than the push and glide line, until you get to really slow velocities, not associated with regular swimming speeds. In addition, for most of the swimmers we have tested using the push and dolphin kick immediately from the wall typically produces a line that is slower than push and glide or the push and flutter kick to somewhere around 1.5 meters/sec. because most swimmers are really not as good at the dolphin technique as they think, and stay underwater to long and breakout well below their regular swimming velocity. But for that particular application, our technology can specifically define that intersection precisely without guesswork. Would I be correct that your values for acceleration, power, and force are derived from the velocity data? If so, the force would be net force (propulsive - resistant drag) on the swimmer rather than propulsive force?They are derived from the velocity data, and at this time, I would agree with you, because our values from the velocity meter were slightly higher than the hand sensors. That is why on the post, I used the values from the hand sensors and not the Velocity Meter. I also assume that the Aquanex measures pressure rather than force, i.e. it doesn't tell you what direction the force is in, and the pressure has to be multiplied by the surface area to determine the total force? If so, someone with a windmill style pull might be exerting force near the top of the stroke but much of that force would be downward and not be contributing to forward propulsion.I believe from the synchronized video, we can make some assumptions about the direction of the force/pressure through any part of the stroke cycle, and we have developed a very effective method of demonstrating that effect. The force telemetry I have seen with freestyle up to this point shows max force or pressure as you call it, occurred in general terms somewhere under the shoulder. To date, I have not seen any telemetry where the max force/pressure value for a stroke cycle occurring anywhere during the initial phase of a stroke cycle for freestyle. And if our comparable numbers are anywhere close to correct 20 to 30 something pounds of propulsive force does not seem very high to me, but as I said earlier, may be those are high numbers for free swimming. Also, when dealing with pressure the total force is proportional to the surface area (actually projected backward facing surface area would be the effective area) so someone with a bigger arm (or better oriented arm) could exert a larger propulsive force than a smaller arm (or less well oriented arm) even though the pressure they are generating is smaller.This is where I think we differ. When you speak about how one person could produce more or less propulsive force, what I think you leave out is during the stroke cycle as propulsive force is progressively being generated to its peak during a stroke cycle, what is also concurrently happening with the instantaneous velocity of swimmer? I believe I have already given you evidence to the answer of that question. It seems to me that the velocity meter inherently measures net force so you need something more to tease apart propulsive and resisting drag forces. The pressure sensor helps in this regard but requires effective surface area to determine propulsive force. Video data taken from the front could help determine area, although an outline taken from the front angle and combined with out of the water measurements could do the trick at the expense of a lot of calculations, although I guess computers can take care of those.At this time, the Velocity Meter could be measuring net force, and more work needs to be done in this area. This was the first time where two devices collected telemetry at the same time, so it's never good to jump to any conclusions without careful review, but the initial results were encouraging. Obviously these kind of measurements are not as easy like with other sports because the physics of moving through the water are not analogous to movements or measurements on dry land. Have you tried attaching the pressure sensor to the upper arm to see how much drag pressure there is there? That would give some very informative data with regard to your drag hypothesis.Not yet, the first step was to see how close those aerospace engineering alumni of mine could come up with equations that would output values from the Velocity Meter close to the hand sensors telemetry.