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Old 05-28-2010, 06:32 PM   #1
Latham Fell
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Adjusting Wall Ball Reps: An Output Calculation

I switch gyms frequently, and one thing I can never seem to find is a 20# wall ball. So, I did the output calculations for when I have to use a 16# or 10# ball. I am a 180#, 69" male, but I imagine these calculations are still pretty close for other body sizes. My methodology is below, so you can duplicate my results for your body size if you like.

The bottom line is:

-If using a 16# ball, do 10% more reps.
-If using a 10# ball, do 25% more reps.


Methodology:

I used the Catalyst Athletics output calculator, located here: http://www.cathletics.com/resources/powerOutput.php

To find the work output of one wall ball rep, I added together the work output of a weighted squat, and the force acting on the ball as it travels from my face at the top of the squat to the 10' mark (a distance of about 4 and a half feet).

Work output of squat portion of rep (from Catalyst output calculator):

20# ball: 237.39 ft-lbs
16# ball: 228.6 ft-lbs
10# ball: 215.41 ft-lbs

Work output of remainder of rep:

20# ball: 20# times 4.5 feet = 90 ft-lbs
16# ball: 16# times 4.5 feet = 72 ft-lbs
10# ball: 10# times 4.5 feet = 45 ft-lbs

Total work output for one rep:

20# ball: 327.39 ft-lbs (237.39 + 90)
16# ball: 300.6 ft-lbs (228.6 + 72)
10# ball: 260.41 ft-lbs (215.41 + 45)

From here it is easy to calcuate the work ratio.

327.39 divided by 300.6 is 1.09. Therefore, 100 20# wall balls is equivalent to 109 16# wall balls.

327.39 divided by 260.41 is 1.26. Therefore, 100 20# wall balls is equivalent to 126 10# wall balls.
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Old 06-01-2010, 12:37 PM   #2
Walker Fenz
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Re: Adjusting Wall Ball Reps: An Output Calculation

Quote:
Originally Posted by Latham Fell View Post
So, I did the output calculations for when I have to use a 16# or 10# ball. I am a 180#, 69" male, but I imagine these calculations are still pretty close for other body sizes. My methodology is below, so you can duplicate my results for your body size if you like.
Crossfitters: Not just Strong, Smart too ;-)

This is cool, thanks for sharing.
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