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

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Old 10-13-2007, 04:28 PM   #1
Hari Singh
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Measuring Work and Power

CrossFit defines fitness as “work capacity across a broad range of time and modal domains.” Since the objective is increased work capacity, perhaps there should be an easy way to provide CrossFitters with a measure of the work done during any given WOD.

The answer to the question of whether an athlete should increase the weight or decrease the time is always “yes” (i.e., do both). But as a practical matter, the better performance is the one that requires the greater power (= work per unit time).

For any given athlete, it is easy to show, for example, that Grace done with 95 lbs in 7:30 is less of an effort than doing it with 115 lbs in 8:00. The athlete should know this and be aware of the precise difference in work and power.

Weights and times are readily observable. Work and Power need to be computed, but since the equations are simple and standard, why not provide a simple screen with each WOD to do the computations. (Think of the BMI screens that request height and weight and return BMI). With a similar setup for the WOD, instead of simply recording weights and times, the athlete can record work and power.

It should be fairly easy to develop a simple 6-input screen that would work for just about any WOD. The screen would return the athletes total work performed and average power output.

As inputs, use:

BW (Body Weight)
H (Height)
W1 (weight # 1)
W2 (weight # 2)
W3 (weight # 3)
T (total time)

So, if the workout is Linda, it is fairly simple to compute the total work done by 55 Dead Lifts (using W1) plus 55 Bench Presses (using W2) plus 55 Cleans (using W3).

The formula for the WOD would make an estimate of how far the weight was moved using the athlete’s height, and then return an estimate of the total work and the average power over the interval.

For an example of how these computations are done, see “Fooling Around With Fran,” March 2005 CrossFit Journal. It should be fairly simple to build a set of macros in Excel for most of the basic exercises. Formula for work done in running, rowing, etc. are also readily available and can be put together as needed for any given WOD. For example:

Helen Work = Work for a person of a given BW running ¾ mile + work for a person of a given Height swinging (Weight # 1) kettle ball 63 times + work for a given height and BW doing 36 pull-ups.

Helen Time is interesting, but Helen Work and Helen Power are perhaps more interesting and more relevant.

Based on the level of interest, I may try to set up a simple Excel spreadsheet on the Black Box (CrossFit NYC) website for some of the WOD’s.
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Old 10-13-2007, 04:36 PM   #2
Jay Cohen
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Re: Measuring Work and Power

Hari;

Interesting idea. You are aware that PM has an Output Calculator, though it's not CF WOD specific.

Link is W/F/S

http://www.performancemenu.com/resou...owerOutput.php
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Old 10-13-2007, 04:49 PM   #3
Hari Singh
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Re: Measuring Work and Power

Jay,

Thanks!

That's exactly what I was thinking of. I'm surprised people don't take advantage of this sort of tool.
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Old 10-13-2007, 04:49 PM   #4
George Mounce
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Re: Measuring Work and Power

Hari - I like the idea of WOD specific numbers, go for it!
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Old 10-13-2007, 04:52 PM   #5
Brandon Oto
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Re: Measuring Work and Power

If we're going to analyze on this level, I think it starts to become incumbent that we establish the power --> fitness link more concretely.

That is to say, if we calculate that Grace in 7:00 minutes at 115lb has slightly higher power output than Grace at 6:00 minutes with 100lb (just making these numbers up), I'm not at all sure whether we can definitively call it "better" for that reason alone. I'll willingly buy CF's "more power is better" position on a general basis, but I dunno whether it's equally clear on this much finer scale, and that seems to be where the usefulness in what you're suggesting arises.
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Old 10-13-2007, 04:56 PM   #6
Brandon Oto
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Re: Measuring Work and Power

To clarify, I read your idea as coming up with comparative power numbers for different variables within a workout. If the notion is to yield a shared number with which to compare BETWEEN workouts (that is, overall power of your Fran versus power of your Helen), that seems more defensible to me, because the margins ought to be larger. And that would indeed be pretty handy, if it gave us a way to quantify "this one lasted longer, but that one really smoked me with the intensity" and the like.
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Old 10-13-2007, 06:48 PM   #7
Barry Cooper
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Re: Measuring Work and Power

Hari,

I understand the thought process, but really it seems to me that if the goal is to track progress over time, the times themselves are enough. If your weight is constant (and presumably your height), then an improved time equals improved work output. If the goal is to prove that big guys do more work, then I can tell that yes, they do. Just watch me do Helen some time. It ain't pretty.

Other than that, that tool would perhaps provide useful motivational information, but in all reality you already know you did a bunch of work. Your back will say: "Hello, Hari, I've been thinking about us and our relationship, and I think we need to talk. . . . ", and of course there is never any good ending to that conversation. Actually, in this case 2-5 days later your back pain leaves you, and you're good. So many analogies to real life.

I will say simply, though, that I've been aware of that tool for some time, and frankly just not sure what to do with it. Take any given WOD, your goal is to improve your time. I really think it is that simple. HOW you do that, of course, can get complicated if you want it to.

Hopefully that makes sense.
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Old 10-13-2007, 06:51 PM   #8
Patrick Donnelly
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Re: Measuring Work and Power

1. It is important to also note the total work of a WOD. It's nice to have a Fran where your average power is 500 watts, but you can only keep that up for about 2:30, giving a work output of 75 kilojoules. If you cut your wattage down to 300, could you keep it up (in some other WOD) for a significantly greater time and therefore do more overall work? I believe the MetCons are meant to increase work over "varying time and modal domains."

2. Everyone's bottom squat height is different, as is their top squat height, their overhead height, their pull-up height, their burpee jump height, etc.

3. People's body's have different proportions, and that must be taken into account. Sadly, you can't. See the current thread about push-ups if you want proof of that.

4. How would you calculate the power for each movement? Net difference between start and end of each rep? The clean has a front squat in the middle of it which would definitely foul that method up, and even for things like a backsquat, you are exerting a force on both the down and the up portion of the squat. If you wanted to calculate the net work and/or power for the total workout, I can save you the trouble: the answer is 0! The plates, med balls, dumbbells and you all end up in the same place after the workout as before.



Why worry about it? If you increase the weight, good for you. You've got more strength. If you degrease the time, good for you. You've got better endurance. If you improve both, that's even better! Just aim for that, because that's really all you need. Calculators like this only help you in comparing yourself to others, and that's not what CrossFit is about.

Edit:
In agreement with Barry, overcomplicating/worrying about things is never beneficial. So why bother?

Last edited by Patrick Donnelly : 10-13-2007 at 06:54 PM.
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Old 10-14-2007, 06:33 AM   #9
Hari Singh
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Re: Measuring Work and Power

Patrick,

1: For a given person and a given weight, Fran always requires the exact same amount of work, no matter the time. What varies is the power.

2-3: I agree that it is impossible to get an exact range of motion for any given person, but assuming correct form, the range can be fairly accurately estimated as a function of height. Whatever the error factor (e.g., underestimating travel distance by, say, 4 inches) it would remain constant for the person. People comparing themselves to one another would not have perfect accuracy, but they also do not have perfect accuracy now, since forms, ROM, etc., vary tremendously.

4: The work done moving a 100 lb bar from the ground to a point 7 feet above the ground is 700 ft lbs. That work is done entirely by the athlete. The work done putting the bar back is zero by the athlete and 700 ft lbs by gravity. The total work done on the bar is zero, but the total work done by the athlete is 700 ft lbs.
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Old 10-14-2007, 07:03 AM   #10
David Wood
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Re: Measuring Work and Power

Quote:
Originally Posted by Hari Singh View Post
Patrick,

4: The work done moving a 100 lb bar from the ground to a point 7 feet above the ground is 700 ft lbs. That work is done entirely by the athlete. The work done putting the bar back is zero by the athlete and 700 ft lbs by gravity. The total work done on the bar is zero, but the total work done by the athlete is 700 ft lbs.
Agreed, although, as with most things involving the human body, it's still slightly more complicated than that. Assuming the athlete lowered the bar under some degree of control (and didn't just drop it in free fall), then even more work was done by the athlete.

I'd certainly be willing to ignore/neglect that part of it to simplify the calculations, though.
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