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Fitness Theory and Practice. CrossFit's rationale & foundations. Who is fit? What is fitness?

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Old 01-22-2008, 10:19 PM   #11
Steven Low
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Re: Calculating Power.

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Originally Posted by Matthew Doyle View Post
Note that the power as calculated by the Performance Menu calculator is basic physics (force x distance / time), and is not related to physical exertion (i.e. calories burned, etc.). It is interesting to see some of the numbers for certain workouts though.

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Old 01-22-2008, 10:34 PM   #12
Dale F. Saran
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Re: Calculating Power.

Some basic physics:

Work = Force applied over a distance. Commonly, F x d
Power = Work per unit of time. Work/time = F x d/t
Note also that F = mass x acceleration (classic Newtonian stuff) F = ma

Finally, classical physics is somewhat unhelpful for calculating power output or work done with the human body. If I hang from a pullup bar, in the classical sense, no "work" is being done (let's skip the initial jump onto the bar and drop off). But you hang there for about 45 secs and tell me you're not working. Now do it 10 times and tell your hands that they're not working. And if it's not "work", then why are you sweating like that, hunh? Riddle me that, Batman. Okay, you get the point.

But for a lot of what we do, it can be useful, although only in a general sense. It's just easier, since your BW is unlikely to change that greatly, to simply compare your workout times (for the same workout) or weights lifted. Why bother converting to to Newton-meters or some other number that doesn't mean anything to you when you can simply look at your Helen time and say, "Wow, 30 secs better this time" as opposed to "1.736 watts better than last time!"

Finally, running is almost impossible to calculate, although I think there's probably something out there somewhere that might help do this.

Last edited by Dale F. Saran : 01-22-2008 at 10:38 PM.
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Old 01-22-2008, 10:37 PM   #13
Joe Cavazos
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Re: Calculating Power.

You are doing work. Your muscles are firing off to keep you on the bar. That takes energy.
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Old 01-23-2008, 12:15 AM   #14
Shane Bradbury
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Re: Calculating Power.

The only reason I bring up power output and how to calculate it and such is because Coach puts such an emphasis on it through out the videos, and especially this quote in the 'Foundations' Journal: "Power is defined as the “time rate of doing work.” It has often been said that in sport speed is king. At CrossFit “power” is the undisputed king of performance. Power is in simplest terms, “hard and fast.” Jumping, punching, throwing, and sprinting are all measures of power. Increasing your ability to produce power is necessary and nearly sufficient to elite athleticism. Additionally, power is the definition of intensity, which in turn has been linked to nearly every positive aspect of fitness. Increases in strength, performance, muscle mass, and bone density all arise in proportion to the intensity of exercise. And again, intensity is defined as power. Power is one of the four defining themes of the CrossFit Program. Power development is an ever-present aspect of the CrossFit Daily Workout."

So I am just trying to learn more about it and trying to see how it is calculated how much it is revelant etc. etc. All comments are appreciated.
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Old 01-23-2008, 07:52 AM   #15
Joe Cavazos
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Re: Calculating Power.

Work and Power are obviously very important and central aspects of CrossFit. However, actually calculating work isn't really important and more of a novelty, since it has no impact on what we do and is, unless you're on a rower, pretty much impossible to calculate.

Take a Thruster, for example. It's easy to look at it and say "okay, the body weighs this much and moves this far, and the bar weighs this much and moves this far... multiply the reps..." and think you've calculated the work. It would be a (somewhat) accurate calculation, if you magically skipped the negative portion of the exercise. You're also letting the bar drop and stopping it, as well as letting your body drop and stopping it, too. How much work is being done there? Tough to say, since you don't know what percentage of the change in energy is being output by you. Then you have the work done by your body to stabilize the weight. Even a movement as simple as the Thruster becomes a mess of technical considerations that are too complex to figure out.

That's why I don't sweat figuring out how much horsepower this movement or this movement generates. It might be a fun diversion, but the inaccuracy ultimately renders it meaningless.

What does matter, though, are the general concepts. For example, if I do Nancy in 20 minutes, then do Nancy in 17 minutes, I've increased my power output, since the work has stayed constant while the time has decreased. If I do a Bear Complex with 135 pounds instead of 115 pounds, I've increased the work I've done, since the weight (and, thus, force applied) has gotten larger while the distance remained constant. CrossFit is concerned (and very much so) with the general concepts of work and power, but not with the actual quantization.
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Old 01-23-2008, 08:14 AM   #16
Brandon Oto
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Re: Calculating Power.

I agree on all counts.

I have also had friends who've done the actual work in trying to calculate these kinds of physical forces basically laugh and laugh at the idea that it's as simple as x weight, y distance, etc. That is not how the body works.
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Old 01-23-2008, 11:22 AM   #17
Shane Bradbury
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Re: Calculating Power.

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Originally Posted by Joe Cavazos View Post
What does matter, though, are the general concepts. For example, if I do Nancy in 20 minutes, then do Nancy in 17 minutes, I've increased my power output, since the work has stayed constant while the time has decreased. If I do a Bear Complex with 135 pounds instead of 115 pounds, I've increased the work I've done, since the weight (and, thus, force applied) has gotten larger while the distance remained constant. CrossFit is concerned (and very much so) with the general concepts of work and power, but not with the actual quantization.
Alright this makes sense to me, using the concepts of work and power and not the actual quantization makes things much simpler. Thanks for answering.
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