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

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Old 04-19-2011, 10:04 AM   #1
Chris Sinagoga
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Intensity = Power

Hey I'm writing a paper about CrossFit and I am going to mention how Intensity is defined as "exactly equal to" power by exercise scientists. I would like to site an external source to back this claim up. Can somebody give me a link/study/source that I can use? I have looked but nearly all of the results either have to do with energy wavelengths or re-direct back to CrossFit.

Thanks
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Old 04-19-2011, 10:59 AM   #2
Jared Ashley
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Re: Intensity = Power

Honestly, I doubt you'll find one, because scientists know that trying to mathematically quantify intensity is nonsensical.

For the same workout, it's intuitively obvious that a shorter time means greater power and greater intensity, but it's impossible to calculate the relative intensities of say a 2:15 "Fran" and a 50-second 400m run. The results are simply meaningless.

It's better to focus on the true statement that short bursts of higher-intensity work has many fitness benefits that are not easily achieved by prolonged lower-intensity work and leave it at that.
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Old 04-19-2011, 05:18 PM   #3
Chris Mason
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Re: Intensity = Power

Where is intensity defined that way by exercise scientists?

Most of them will define it as a percentage of one's 1 rep max (1RM).
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Old 04-19-2011, 06:21 PM   #4
Adam Carlson
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Re: Intensity = Power

You could talk about both intensity as a 1 rep max and intensity as related to horse power. To find horse power, you would need to measure distance moved, time taken to move said distance, weight, etc. Freddy C talked about measuring horse power in his Fran at the cert I attended.
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Old 04-19-2011, 06:47 PM   #5
Troy Becker
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Re: Intensity = Power

Mason has it- more generally, I would define intensity is how close to your ultimate threshold that you perform doing whatever you're doing. Unfortunately, this can never be accurately measured. It can, however, be recognized, however vaguely.
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Old 04-20-2011, 12:08 AM   #6
Mauricio Leal
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Re: Intensity = Power

There is Mechanical Energy (or Work), which CrossFit often refers to, and there is Chemical Energy (or Energy Expenditure), which your typical Exercise Physiology book will often refer to.

Mechanical Work is not terribly complicated to measure -- the human body is a series of levers with mass centers and axes of rotation (joints). In theory, if you could measure their respective trajectories simultaneously in real time, you could determine very closely the mechanical work (and power) being done at any given moment by summing their respective contributions together. In theory. If there is a barbell/external load involved its work contribution is the easiest one to compute, and you can tack that on to the total. In practice we make gross approximations and at the end of the day standardize the movements such that the way we measure "work capacity" is reduced to one variable: time or reps/pts (as in an AMRAP).

To my knowledge, no one has done it yet, but in the near future I imagine it would be fairly simple to place a few accelerometers on various parts of a human and on a barbell or what have you, and pretty accurately track the mechanical work/power output of an individual doing a workout in real time.

Energy Expenditure is a much tougher egg to crack, because it implies knowledge at the cellular level of work done, and the processes that govern that are, needless to say, complex. But surprisingly, it has been done, to a certain degree anyway. Scientists back in the day figured out you can put someone in a chamber and measure the amount of heat they give off while exercising through a measurement process called Calorimetry (google it). It has severe shortcomings however, because there is a significant lag time between one's exertion and the system's measurement, low resolution of changes in exertion level, and a lot of potentially confounding heat sources. The second method they came up with was to measure the gas-exchange ratio (Respiratory Exchange Ratio, or RER) between CO2 and oxygen and draw connections to aerobic output. But this has the shortcoming of (you guessed it) only measuring aerobic output. So a 400m sprint would be grossly misrepresented, a 200m sprint would barely register, and your average CF WOD, well, forget it.

They have some nifty ideas on how to correlate Excess Post-Exercise Oxygen Consumption (EPOC) to anaerobic effort, but long story short they pretty much suck.

Of all the methods CrossFit's is the most intuitive, yet, somewhat surprisingly, the least lab-tested. Apparently no one ever thought to look closely at the human body as a machine, at least when it comes to exercise and particularly performance in exercise, where calories still dominate the conversation outside of CrossFit.

P.S. Here is a quick textbook ref (wfs) on the basics of this stuff.
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Old 04-20-2011, 04:08 AM   #7
James Yates
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Re: Intensity = Power

Quote:
Originally Posted by Chris Sinagoga View Post
Hey I'm writing a paper about CrossFit and I am going to mention how Intensity is defined as "exactly equal to" power by exercise scientists.
I think you need to consider that there is a correlation between power and intensity for a given individual for a given movement/exercise.

A phrase like "exactly equal to" is gonna get you in trouble. The other simple fact is that power output is necessarily different between a 40 yd sprint and an 800, yet they may both be performed near max intensity. Compare a run to a lift and, well....

It is also different for different people... I am a horrible swimmer. I expend tons of energy moving through the water inefficiently. If you measured my calories burn, it is probably very high, yet if you timed me, the time would be unimpressive. A good swimmer could easily match my speed, while not working nearly as hard... how do you account for that difference in power?
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Old 04-22-2011, 06:39 PM   #8
Chris Sinagoga
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Re: Intensity = Power

Mauricio,

thanks for the response. I've always wondered if they're ever going to have a workout that says "post power output to comments"...

James,

I was concerned with the phrase "exactly equal to" as well. But that's how it was presented at the Level I, and numerous videos on the journal. And to answer your question, the stopwatch would account for the difference in power, right?. Assuming you two weigh the same?
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Old 04-22-2011, 11:57 PM   #9
Katherine Derbyshire
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Re: Intensity = Power

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Originally Posted by Chris Sinagoga View Post
thanks for the response. I've always wondered if they're ever going to have a workout that says "post power output to comments"...
A couple of workouts measure rower output in calories...

Quote:
I was concerned with the phrase "exactly equal to" as well. But that's how it was presented at the Level I, and numerous videos on the journal. And to answer your question, the stopwatch would account for the difference in power, right?. Assuming you two weigh the same?
Just because the Level 1 cert explained it that way, that doesn't mean your professor will buy it. CFHQ doesn't actually seem to pay much attention to scientific rigor. IMO, absolute statements about something as complex as human physiology are automatically suspect.

Exercise science has several measures for intensity: % of 1RM for lifts, % of VO2max for aerobic exercise, etc. Convincing me that *all* of them are "exactly equal" to power is going to take some doing.

Katherine
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Old 04-23-2011, 08:15 AM   #10
Eric Montgomery
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Re: Intensity = Power

Quote:
Originally Posted by Chris Sinagoga View Post
Mauricio,

thanks for the response. I've always wondered if they're ever going to have a workout that says "post power output to comments"...

James,

I was concerned with the phrase "exactly equal to" as well. But that's how it was presented at the Level I, and numerous videos on the journal. And to answer your question, the stopwatch would account for the difference in power, right?. Assuming you two weigh the same?
I think there are just too many minor variables at play to make a 100% accurate power assessment on anything other than rowing or Airdyne biking where you have a computer measuring exactly how much work is done.

For example you could have two guys, both 6' and 200lbs, cranking out 95lb thrusters at the rate of 20 per minute but producing very different average and peak power outputs. Anthropometric variations (i.e. one has longer arms, one has shorter femurs and a longer torso, where they carry most of their bodyfat, etc.) will produce slight variations in their ROM, and you'd have to consider how they're actually doing the movements. One might do 5 reps in 10 seconds then rest 5 seconds and repeat that process 4 times to complete the minute, while the other could keep a slow and steady pace throughout the minute. Plus inefficiencies in the movements could be at play just like James mentioned with his swimming.
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