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

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Old 11-15-2006, 10:12 PM   #1
Eric Cimrhanzel
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"From load, distance, and time we calculate work, and work-capacity/intensity/power."

That's great, but there's a small problem with using Power to measure Fitness. Not all loads are the same on the human body, even given the same weight and movement. Also, given the same distance, the load on the human body is different depending on the stability with which the distance is crossed.

Easy example: Do Fran with a 105lb barbell, two 53lb kettlebells, and a 105lb sandbag. Now do the pullups on a solid Pullup bar, then gymnastics rings, then a T.A.P.S. pullup bar (a pullup bar suspended by one chain). That's 9 different variations of the same 21-15-9 workout. As you progress from one type of apparatus to the next, each exercise--the Thruster and Pullup, respectively--becomes increasingly more difficult.

Now you can say that the Work, expressed by (Force*Distance), is the same for each workout, but simply calculating Power (Work/Time) will not give you an accurate estimation of fitness unless the apparatus is always the same, which it shouldn't be if you're going for pure randomization and variation in your program.

Stated another way: If I do Fran with a 95lb barbell and on a solid Pullup bar in 4 minutes flat, and my buddy next to me does Fran in the same time with a 95lb sandbag and on a T.A.P.S. bar, assuming that we execute every rep to full depth and extension, he is abviously more fit than I am, even though according to Physics formulas we are producing the same level of Power.

I'd love to hear what others think about this. This has been on my mind for a while, and today's WOD quote is what finally brought out my thoughts to the Forum.
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Old 11-16-2006, 03:15 AM   #2
Charlie Jackson
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I think you are referring to efficiency (how well power is converted into from one form to another). Take the overhead squat and the back squat. The weight, distance and time are the same but to a novice, it takes much more power to lift the same weight with an overhead squat. As you technique becomes more efficient, your max overhead squat gets closer to your max back squat even though there is no increase in strength or conditioning.

Compare driving a car with flat tires to driving a car with full tires. The flat tires create more friction and the conversion from mechanical energy to kinetic energy is impeded so it takes more power to move the car with the same weight.
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Old 11-16-2006, 05:48 AM   #3
Andrew Nashel
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Classical mechanics will only be a very rough approximation to any real world system, especially for anything involving biomechanics.

In the Fran example, your friend is firing his stablizing muscles a lot more, expending more energy, and the basic equations don't take any of this into account.
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Old 11-16-2006, 06:37 AM   #4
Ben Kaminski
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IMHO, classical mechanics is close enough in most cases for determining power. Thrusters and pullups are easy enough to characterize using classical mechanics. However, a backflip (with rotational forces) or a static hold (no weight moved) is not as straight forward.
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Old 11-16-2006, 06:45 AM   #5
Jon Gilson
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The calculations employed by Crossfit HQ are rudimentary, per Greg Glassman's own admission. In this case, we're missing the forest for the trees--the fittest athlete is the one capable of producing the most power across the widest variety of exercises. This is an irreducible fact.

The most powerful athlete will give a top-tier performance regardless of the apparatus and its stabilization requirements.

Let's take Greg Amundson, the gold standard of Crossfit-type power production: Do you think it would matter whether you gave him a barbell, dumbbells, two kettlebells, a thick pull-up bar, a rotating bar, a TAPS bar, etcetera?

Hell no. He'd still produce the most work in the shortest amount of time. When you reach that level of elite athleticism, stabilization is not an issue--it is necessarily top-notch, as it is prerequisite to reaching elite status in the first place.

Crossfit is not a university-level course in applied physics, and therefore disregards the intracacies of the discipline. In fact, I would posit that the nuances of biomechanics do not change the general outcome of the calculations to a statistically significant degree.

Despite the inattention to detail, classical mechanics provides a sound basis for understanding why we do what we do, and serves to frame the entire concept elegantly.

Carry on.



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Old 11-16-2006, 06:51 AM   #6
Larry Cook
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In addition to Charlie and Andrew's excellent comments, I think you may be mis-applying the result of the calculation. To expect the power output for different exercises (even if only slightly different) to be comparable is like expecting the power output when doing body weight squats to be similar to the power output when doing HSPUs. Your basic premise of "That's 9 different variations of the same 21-15-9 workout" seems off to me.

Also, I don't think Crossfit defines fitness as having greater power output for just one WOD (e.g., Fran). The fitter individual has greater power over a wide range of activities, and also exhibits better overall skills as defined in the "10 general physical skills".

I think that the power output calculation is great for 3 things ... 1) comparing the power output of 2 different individuals doing the exact same exercise(s) ... A vs. B, 2) comparing an individuals performance for a paricular exercise at different points in time ... A1 vs. A2 and 3) comparing any individuals power to some theoretical maximum A vs. X.


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Old 11-16-2006, 10:32 AM   #7
Lincoln Brigham
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Rudimentary - yes.

Bear in mind that most exercise programs don't take power into account at all. To most other programs, walking a mile in 15 minutes is the same as running a mile in 5 minutes. To most other programs, a half-hour of exercise is the same whether it's doing "Angie" or doing tai chi.

Power is a better metric for fitness than work, even though power is more difficult to measure. Power is metabolically expensive. Power is good. Calculate power as best you can, that's all.

(Message edited by lincoln on November 16, 2006)
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Old 11-16-2006, 12:33 PM   #8
Keith Wittenstein
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Excellent discussion. In a strange way I agree with everyone. That never happens. Power is the best metric we have at the moment to judge fitness no matter how rudimentary it may be.

Yes, there is something to be said for making your life harder by doing workouts with unstable objects, but Coach has observed that the power output is asymtotic and approaches around 1/2 horsepower per minute in top performers like Amundson. At some point I would think it makes little difference what you are lifting when you reach maximum levels of power output. If there is a person out there that has a sub 3min Fran with sandbags and ring pullups, then switching to a barbell and fixed pullup bar might shave a few seconds but probably not much as that person is already approaching the maximum power output.

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Old 11-16-2006, 01:51 PM   #9
Andrew Nashel
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So, what does Crossfit use for the load factor of the human body? I've seen people use about 80% of bodyweight for a squat.
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Old 11-16-2006, 03:51 PM   #10
Eric Cimrhanzel
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I agree with you Keith: "Power is the best metric we have at the moment to judge fitness no matter how rudimentary it may be." I'd just like to hear if there is a better way to do this. All ideas are welcome.

And great observations by everyone! As Jon observed, I may have been a bit myopic in my observation, but I would still like to hear more thoughts on this.

Also, to Jon (and to anyone else who can answer): Let's take the issue of gettting to Elite athletics. Do you think that using only unstable loads (NOT unstable surfaces to load on! That's a completely different discussion!) such as Ring Dips, T.A.P.S. Pullups, sandbags, etc, get us to an elite level faster than if we either A) only used stable loads --bar Dips, barbells, solid Pullup bars, etc--OR mixed both unstable loads and stable loads (like it seems most CrossFitters do)?

Then, at what point do we reach margins of diminishing returns with unstable loads?

Lots to think about!
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