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Old 01-27-2010, 05:03 PM   #11
Jeremy Kauffman
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Re: Versatile fitness tracking for affiliates / members

I was talking to Brad in depth about this idea yesterday and I think it's possible. You would essentially need the following information, for each exercise:
  • A formula equating a person's height to the distance the center-of-mass travels
  • The percentage of a person's weight that moves in each exercise (e.g. for a squat, the calves aren't really moving)

Obviously, these numbers would not be perfect. But as Maurico points out, as long as they're reasonable and consistent you can gain information. Certainly, this information is a better estimate than simply guessing.

I think the larger sticking points are:
  • Collecting the data. How do you figure out how much mass moves how far?
  • Handling certain exercises. How much work is a lunge, which is primarily in the horizontal plane? How do you handle an exercise like SDHP, where the weight is moving a larger distance than the COM?

If anyone has any ideas for these I'd love to hear them. I think this can be definitely be done.
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Old 01-28-2010, 07:12 AM   #12
Lawrence "Bo" Boland III
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Re: Versatile fitness tracking for affiliates / members

Quote:
Originally Posted by Jeremy Kauffman View Post
I was talking to Brad in depth about this idea yesterday and I think it's possible. You would essentially need the following information, for each exercise:
  • A formula equating a person's height to the distance the center-of-mass travels
  • The percentage of a person's weight that moves in each exercise (e.g. for a squat, the calves aren't really moving)

Obviously, these numbers would not be perfect. But as Maurico points out, as long as they're reasonable and consistent you can gain information. Certainly, this information is a better estimate than simply guessing.

I think the larger sticking points are:
  • Collecting the data. How do you figure out how much mass moves how far?
  • Handling certain exercises. How much work is a lunge, which is primarily in the horizontal plane? How do you handle an exercise like SDHP, where the weight is moving a larger distance than the COM?

If anyone has any ideas for these I'd love to hear them. I think this can be definitely be done.
I'm pretty sure that BTWB does a work capacity calculation based on measurements of the body:

-Foot to knee
-Knee to hip
-Shoulder to elbow
-Elbow to fingertips
-Length of torso

Then there are some formula's already out there that calculate the force/work required to do a thruster,squat,etc.
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Old 01-28-2010, 11:52 AM   #13
Roger Harrell
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Re: Versatile fitness tracking for affiliates / members

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* Collecting the data. How do you figure out how much mass moves how far?
Analysis of each movement. I've got 36 exercises completely broken down for this. Then we look at anthropometry to work out variations in people. Measurements of specific body segments for individuals can be added for increased accuracy, but for most purposes averages work well.

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Handling certain exercises. How much work is a lunge, which is primarily in the horizontal plane?
The only work in a lunge is the vertical component. Running is a far more complex situation, where work is a polynomial relative to speed and distance.

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How do you handle an exercise like SDHP, where the weight is moving a larger distance than the COM?
External weight movement and body segment movements are treated separately. Not difficult.
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Old 01-28-2010, 01:13 PM   #14
Brad Motzer
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Re: Versatile fitness tracking for affiliates / members

Roger, you're basically where we are in terms of discussion, but I'd greatly disagree that propelling yourself forward in a lunge is much more challenging (because of increased work) than a stationary lunge or split squat. As far as mono-structural or "cardio" work, we run into differences because gravitational pull on the body is not the same as vertical displacement and if we're comparing work we need to find a formula for them to be equalled. The speed aspect should be taken care of by your effort and reflected in your workout time. Therefore, we would need to devise a formula that just equates how far of a distance you need to run in order to to get the same amount of work (force x distance) to another exercise like a pull up. The simplest way to define force is to use weight acting in opposition to gravity. But mono-structural exercises keep you the same vertical distance from the ground throughout the exercise (for the large part, I do realize that acceleration phases and max speed phases of running have different body position angles) and gravity doesn't work the same as when we move vertically. Otherwise an 8" pull up would be the same amount of work as an 8" run. So what Jeremy and I will be trying to figure out (and what we hope to receive some help with) is what formula could we use to make the work equal between mono-structural exercise and vertical distance exercise. To further complicate things past running, we'd also like to find a similar formula for swimming, biking and rowing since numerous affiliates make use of those types of cardio, too.
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