Physics

25
Nov

Physics

Power = Force x Distance / Time

This is the CrossFit prescription – move a large load (force), a long distance (distance), quickly (time). And if you generate more power, you will increase your intensity.

Think about it. Let’s take your bodyweight (force) and move it 5km (distance) in 30 minutes. Now let’s repeat that, but do it in 25 minutes. Your power increased. You were more intense. Pretty simplified (I know), but still cool to think about.

So why would you want more power (intensity)? Well, increased power output will yield increased results. Do something faster, and you improve. Isn’t that the goal of every workout?

This concept can even be used (theoretically) for scaling workouts (ie. choosing the right loads). Let’s look at an example. A few weeks ago, we did Diane. I did 45 deadlifts at 225# and 45 handstand pushups. When I plug my height and weight into the Catalyst Power Output calculator, along with the movements and weights, my power output was 78 foot-pounds per second.

Let’s say I did that same workout, but used 275# instead, AND, it took me 3 minutes longer? Using the calculator, my power output would only be 64 foot-pounds per second (that’s quite a drop!).

Now, this is all great, in theory. But it can be used in practice. We have goals for every workout (ie. under 10 minutes for Fran). So when we ask you to scale, it’s because we want you to generate the most power possible. BAM! Doesn’t that blow your mind?!

Justin generating a ton of power with his double kettlebells!

9 Responses

  1. Wicked picture, looks like he’s firing at something. *pew pew pew*

    Totally agree, much better to get a more intensive workout while you are at the box, even if it means a little bit of scaling.

  2. Heather S

    Great post! While it’s always a thrill to be able to write “Rx” after a WOD (I don’t get to do that very often) I know it’s a “wod done well ‘ when I’m gasping and and making sweat angels on the floor!

  3. Lora

    Mind blown 😉

    Great post, Kevin. If you are not able to do the workout as intensely as intended…then you haven’t worked as hard as you could have. There is a point of diminishing returns. It took me a while to “get” this concept when I first started doing Crossfit. I was always chasing “Rx” and probably cheating myself on some great workouts because of it. There is no “shame” in scaling. In fact, you will probably get a better workout because you scaled (and we are not even talking about technique, form, etc.)

    I hope a lot of people get to see your post today. It is excellent information for the newcomers and a great reminder for those of us who’ve been around for a little while.

  4. WU x2

    1 mile run = ~10 mins (not in a rush) 😛

    Volume: EMOTM 15 mins – Pushups = 105 (15 x 7 reps)

    … then rest 1 min …

    AMRAP 1 min Pushups= 28 (25 unbroken, but slow)

    Not bad for a sunday session at home….

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