9/19/07

Food For Thought

Gary Winckler send me the following thought from Esa Peltola. Esa is a great coach and sport scientist who now works at ASPIRE in Qatar, he was formerly the sport science coordinator for Athletic Australia.
"The fastest movement does not always produce the highest power implying that high power does not always mean fast force production"

9 Comments:

At 9/19/07, 11:41 AM, Anonymous Anonymous said...

I would love for you to extrapolate the implications of this statement for us not-so intelligent intellectuals. :)

Jonathan Hewitt ATC
move.beyond@hotmail.com

 
At 9/19/07, 12:57 PM, Anonymous Laura Mac said...

We actually see this a lot in rowing. When an athlete suspends their weight off an oar handle against the water, their legs should not be able to push down quickly. The load is too heavy for that. Instead, they can begin to move the weight slowly and then increase the velocity as they gain momentum. If a rowers legs push down fast, they are NOT suspended! Hope this helps!

 
At 9/19/07, 2:05 PM, Anonymous Anonymous said...

So it's kinda like fly fishing. If you bring the rod back too slow or not fast enough the line will not properly load behind you so that you can make a quality cast. However the longer the line is from the rod, the time allowed for the line to load must also be adjusted. The same for shorter line, shorter quicker casts, longer line = lengthier motion.

Thanks!

Jonathan Hewitt ATC
move.beyond@hotmail.com

 
At 9/19/07, 9:24 PM, Blogger Bonnie said...

The fly fishing example is of a different physical process: waves. The reason timing is important there is that you have to wait for the motion started at the rod to reach the tip of the line (just like a wave on a string with one free end).

The issue of power's relationship to force (F), distance (D), and time (T), P = (FD)/t, is well illustrated in the rowing example. When the distance is constant, requiring a greater force, say twice as much force, buys a person more time (twice the amount of time) in which to complete the motion while maintaining the same power.

One could also think of momentum as an intuitive example of these ideas. When a boxer punches a bag that is swinging towards them, the bag will stop swinging. Although the movement at the point of contact is slow, and the distance short, the power may well be the same (or greater) than when the boxer hits a bag that is swinging away.

Bonnie Kirkpatrick

 
At 9/20/07, 3:05 PM, Anonymous Anonymous said...

Thanks Bonnie,
I didn't do well in my explanation about fly fishing but the rod tip is what's analogous to the power example of rowing. As the fly is pulled from the water, the starting movement is slower, as the resistannce of the water decreases the speed of the rod tip increases and thus produces enough power to cast the entire line backwards, load, and with the forward motion of the rod, cast the line forward again. The similarities are in the act of oversoming the water with oar or a flyline. The return stroke of the rower is more like the forward or backward cast of a flyline once it has left the surface of the water. If the rod is loaded too fast in either direction the line will break and the line will not be casted and fall short of the target distance. So the gradual increase in power over time is the same principle of the rower. Back to the post, sometimes slower production of power results in a higher power output overall than does a very fast movement. Right?

Thanks again,
Jonathan Hewitt
move.beyond@hotmail.com

 
At 9/20/07, 3:32 PM, Anonymous Kristof said...

It is true that the fastest movements do not produce the highest power and that high power does not always mean high 'velocity'.

But to assume high power doesn't lead to 'high force production' is false. Power is the rate at which mechanical work (force*distance, as in Bonnie's example above) is being done. In most sports the distance through which force is applied stays constant (e.g., motion of the rower). So with distance/ROM constant, more power means either more force or a shorter period of time to apply force. In both cases the rate of force production would increase.

I would perhaps add another question and ask where would we want the power to go: 1) shorter time interval or 2) more force.

kristofk@hotmail.com

 
At 9/20/07, 9:55 PM, Anonymous Anonymous said...

Physics aside, I think that QUALITY of motion can be as much or more of a factor as QUANTITY.

By QUALITY I mean timing and sequencing.

Jeff W
Buffalo

 
At 9/21/07, 12:33 PM, Anonymous Kristof said...

Jeff, I totally agree. I should have included an analogue similar to your distinction in my comment. In my mind 'shorther time intervals' would be your qualitative (i.e. temporal) factor, whereas 'more force' would be a quantitative factor. In any case the tradeoff between these two factors would depend on the objective.

 
At 9/21/07, 12:39 PM, Anonymous Anonymous said...

kristof,
I agree, Optimal power production does not assume optimal outcome. I think it is very important to also ask what are we trying to accomplish by producing this force? Also how often do I need to produce this force, meaning how frequent. As for quality that's where power endurance comes into play. As fatigue increases I beleive movements have an incraesed potential to become sloppy.

Jonathan Hewitt
move.beyond@hotmail.com

 

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