I want to get some simple, black & white facts on the table....Rxing the workout is absolutely a phenomenal feeling! You've been working so hard in the box to be able to write those two little letters next to your score on the board, and you finally got it! Let's take a second to diagnose wether that was the best choice for your fitness, or if scaling would've been the better option for the end result. Let's first talk about what intensity is. Your intensity in a workout is exactly equal to your average power output in a workout. This means, in our world, the CrossFit world, you can put an exact number, or measurement to your intensity level. Our intensity levels have everything thing to do with our fitness. If you want a higher back squat you need more intensity, do you want to lose body fat and gain lean body mass you need more intensity. Anything we want out of a fitness program we can get with intensity. We will do this shortly. Now, your power output is the work you did in a given amount of time. There is two ways you can look at how powerful you were in a workout that will have everything to do with whether or not Rxing the WOD was worth it. Let's take something simple like the Benchmark WOD Fran. In the March of 2005 CrossFit Journal Article "Fooling Around With Fran" (http://library.crossfit.com/free/pdf/31_05_fooling_with_fran.pdf) Coach Greg Glassman put Greg Amundson through Fran with three different weights. Here is the intensity, i.e. power output, breakdown.
To figure out work done we use the equation force x distance/time=power. Here is the breakdown of power output below:
Fran done as: 21-15-9 reps of: Thruster @ #95 Pullup
Fran done as: 21-15-9 reps of: Thruster @ #115 Pullup
Fran done as: 21-15-9 reps of: Thruster @ #75 Pullup
If you take a look at the bottom line average power output in the tables above you see Fran at #95 had an average power output of 315 ft. lbs./second. Fran at #115 had an average power output of 253 ft. lbs./second. While Fran done at #75 had an average output of 338 ft. lbs./second. Looking at this data you could look at this two different ways. First off, let's completely get rid of Fran at #115 because you can see the power output is significantly lower than the other two. The argument is to be made using tables 1 and 3. Comparing these two you could argue Greg is better off using #75 because he had a higher power output and this could be true. Here is my opinion whether Greg should do this Rx next time. If he went unbroken and did not stop moving through all those thrusters I would say it's time to move up to the Rx weight. Now, if he went up to the Rx weight and his power output dropped down to the 200's I would now consider taking him down a little more.
To wrap this up I would say the main things to consider would be "how much am I staring at my barbell, i.e resting, during the wod?", "am I finishing the workout within the intended stimulous the programmer had in mind for this workout?", and/or "am I going to get fitter from my output I just had in this workout?". You have to be honest with yourself and check your ego at the door. Ask yourself those questions and if you are being honest with yourself you will have the answers you need. Just remember, when you are 80 years old and you are still able to run around on the playground with your great grandchildren does it really matter how many times you were able to write Rx next to your name on the board.