Friday, April 19, 2013

Power is the Path to Fitness by Jeff Pruitt


Written by Jeff Pruitt of CrossFit 316

How many of you try and use the prescribed weight for a workout just to prove to yourself that you can do it? Let me be the first to tell you that prescribed weights suck. They’re fine for competition, or benchmark workouts to see where you rank among thousands of other CrossFitters, but they are definitely sub-optimal for improving your general level of fitness.

How do you pick what weight to use during a workout? For too many people it’s just a random decision and that’s unfortunate because while it may not be rocket science, there is a certain amount of science involved in getting more fit. I’m going to explain how and why to choose the appropriate weight in order to maximize the efficiency of any given workout.

In CrossFit we define fitness as increased work capacity across broad time and modal domains. In plain English that means improving your ability to do more work using different movements in workouts of varying times. And as anyone that has done a CrossFit workout will attest, increased work capacity comes via intensity.

Now the beauty of intensity is that we can measure it. Intensity, as we define it, is just the average power you produce during a given workout. We don’t need to make this overly complicated but just know that in physics average power equals the amount of work done divided by the time taken to do the work.

That means there are two paths to increasing the average power of your workout – the first would be to increase the weight used and the second would be to do the workout faster. Many people choose the first approach because it seems harder or because of some bogus notion of prescribed weights but this is often counterproductive. Many times dropping the weight and doing the workout faster will actually increase your average power and thus improve your fitness faster. The reason is because there is no work being done while you are resting and staring at the bar.

There are formulas that attempt to map the number of reps in a workout to some percentage of your one rep max and that is exactly why you’ll see those percentages show up on the whiteboard for certain workouts. But practically speaking, the weight (or scaling for gymnastics movements) you should use is one that allows you to do the workout unbroken but right on the edge of having to rest.

Now when we do strength work we are looking for a different stimulus and thus we increase the rest periods between lifts, but for metabolic conditioning there is simply no arguing with physics and physics says you need to pick a weight that makes sense in order to maximize your fitness level. So don’t just think about finishing a workout with a prescribed weight; think about maximizing average power by doing the workouts unbroken or with very minimal rest…

This post was originally written for Guerrilla CrossFit by Jeff Pruitt