Take My Idea - Measure Any Exercise

I’ve had this idea bouncing around inside my head for a long while and I’ve come to the realization that I’m never going to see it to fruition. Instead of letting it just rot on my computer, I thought I’d give it away instead. If you want it, take it. If you want to chat about it feel free to contact me.

Note: I’m trying to write out this idea as clearly as possible but since it isn’t a fully formed idea in and of itself I may not make complete sense — proceed with caution.

The Problem

Quantifying the output of a workout is hard for many of us. If you’re a runner or cyclist then you can use distance, speed and even heart rate easily enough. But what if you do CrossFit, P90x or lift weights. Well, you can record weights lifted and time it took but, as this style of workout is designed to do, it changes so often that measuring your performance over any significant length of time is not all that useful.

The Opportunity

Workouts of varied intensities and ever changing routines are now trendy. P90x, CrossFit and lots of local “boot camps” serve this crowd. It’s still a minority of the general exercising public but it’s a segment that is growing rapidly and those trend-setters have no way good to measure their performance.

There are plenty of sites that allow you to record and track these types workouts and even compare them to other individuals, but none do anything clever to compare across different workouts (in an “apples to apples” way) or handicap based on body type or size.

In short, these people, who have money to spend, have a need that isn’t being met.

The Solution

The common denominator in every exercise routine, regardless of its methodology, is that you’re moving weight (even if it is just your body-weight) over a distance for a given amount of time. Using those inputs you can calculate power output (in Joules and Watts) and use that measure to compare anything, equitably. Rowers, treadmills, stationary bikes and ellipticals often provide this measurement but there is no reason you can’t get this measure for everything else. That includes pullups, pushups, cleans, deadlifts, runs, swims, etc.

Power output measures can not only factor in weight lifted or distance traveled, but it can include other variables such as a person’s height and weight. Using power output to measure performance is a great equalizer. Imagine a method where you can compare a power-lifting session to a run to see which was “more work.” Or how fun would it be to get fair comparison of performances between a 250lbs bruiser and a 100lbs waif.

How it Applies

With me so far? Here a some ways the measurement can be presented to users:

• Graph workout output for a single person over time, no matter what form of exercise they choose and clearly show their progress.
• Compare two athletes handicapping for weight and size differences
• Get teams together to compete for most power generated. That could really be fun!
• Provide real-life equivalents for how much energy they generated (enough to light a 100w bulb for an hour, enough to power a radio for a week, etc.)

Calculating Power

The first problem I faced, how to actually calculate the power output, was simple enough to find in Google — Joules = force x distance. Joules is a measure of power and Joules over time is described as Watts. To follow is a breakdown of the Joules equation.

• The distance variable represents how far something moved and is measured in meters in this formula.
• The force variable can be calculated by taking the weight of the object moved (in kilograms) multiplied by 9.8. The 9.8 constant represents the fight against gravity which one must do to lift something.
• To derives Watts from Joules you simply divide the Joules by the number of seconds the activity took.

That’s a very brief overview. If you’re interested in learning the details in this formula you can read more about the particulars in the Work section of this article — or just take my word for it and keep reading.

Lets put this to an example:

• I weigh 70kg
• I jump .5 meters in the air
• It took me 1 second to perform the task

As a result I generated 343w in that second. That’s enough to power a 100w light bulb for 3 seconds or this computer for almost 2 minutes!

Here is the breakdown of the above calculation (Remember Joules = force x distance and force is weight against gravity in our calculation):

• 343 Joules = (70kg * 9.8) * .5m *343 watts = 343 Joules/1 second

Thats a pretty simplistic example but it gets across the main premise anyway.

Deriving the Variables

With the power calculation figured out I next needed to determine how to fill the variables of the equation. Distance traveled seemed easy at first until I started to think about it. How far does the weight travel in a deadlift or a pullup? (I’ve done some work here but more needs to be done.) I started with this graphic which shows the average percentage of the body a particular part represents. For example, the distance from the ground to your hip is 53% of your height. Lets say I’m 1.8 meters tall. That means the distance from my hips to the ground is .95 meters (1.8 * .53). Follow?

Using these measurements you can compute distance traveled for an exercise. Let’s look at the pullup as an example. I’m 1.8m tall and, according to the chart, the distance from my forearm to my shoulder is 33.2% of my height or .60m. That is the distance I travel in a pullup. With that I plug that distance and my weight of 70kg into the aforementioned equation. According to the calculation my pullup would generate 416 Joules and if I did a pullup at a rate of 1 every 3 seconds I would generate 136 watts per pullup. Pretty cool huh?

((70 * 9.8) * (1.8 * .332))/3 = 136

Now you may be thinking what about the body weight moved? In the case of a pullup it is 100% of your body weight but that isn’t true for all exercises. What about a sit-up? For that problem I used the same sort of methodology I did for distance. I found this PDF which has a percentage of a body’s weight each body part represents (check out the tables in the front of the publication). A sit-up would be your body weight less the weight of your legs.

What’s Already Done For You

I’ve gone through the trouble of putting all of the information I gathered into a spreadsheet which includes the blueprint for measuring over 30 exercises. That should be enough to get anyone started. It’s a bit messy but if you’ve read this far and understand where I am trying to go with this it should make sense. I hope.

I’ll leave it to your imagination how to implement this for the user but I hope for three things with this post:

• People confirm this idea makes sense — Or point out some fundamental flaw in this whole scheme.
• I’ve made it clear enough that people actually understand the need for it — I would use it.
• Someone picks it up, runs with it, makes a killing, and sends me a nice case of beer as a thank you in the future.

I’d love to hear any feedback on this idea and certainly let me know if you take the idea and plan on bringing it to life — I’d love to see that!