# Weight of a pushup?

1. Aug 23, 2008

### lax1113

Hey guys,
I was just wondering what would need to be known to determine the weight that one encounters when they do a pushup. I'm guessing that you would need the angle of your body to the floor and the weight of the person. So, with that being said, where would i go from there? Because the weight is split somehow between your upper body and legs i suppsoe right? Any thoughts would be appreciated.

Thanks,
Ben

2. Aug 24, 2008

### rock.freak667

You'd also need the distances of your feet to your arms and also from your centre of gravity to your feet. Take moments about the fulcrum. and find the normal reaction of your arms.

3. Aug 24, 2008

### Staff: Mentor

I wouldn't bother with the angle, since it is shallow and it changes anyway. Just the CoG and distances like rockfreak said.

4. Aug 24, 2008

### Staff: Mentor

Or just do a pushup on a bathroom scale and note the weight.

5. Aug 24, 2008

### atyy

Good idea! If you try that, let us know how the weight (as read by the scale) changes during the pushup. It may depend on whether you do it explosively (like the when you want to clap your hands between pushups), or meditatively (ala qigong).

6. Aug 24, 2008

### pallidin

It would be interesting to have a digital camcorder capturing the movements of the person on the scale and the scale readings.
With that, a suggested enhancement: 2 scales, one for each palm placement/impact.
The scales should be firmly attached to the floor(or otherwise braced) for "explosive" pushups.
Ideally, a third scale for the feet would be utilized, providing for a very complete analysis.

7. Aug 24, 2008

### TeTeC

Maybe the scale will not display the number fast enough. Some scales won't even allow you to have a second measurement, and you actually have to step down and wait.

Try it.

8. Aug 25, 2008

### pallidin

Very true, and is why I did not talk about the scales. But now I will.
Household digital scales have limited usefulness in this. Analog scales would be superior.
But "response" time is important, and either type of standard household scales are not designed for fast response.
Even still, an analog scale would be adequate for a gross analysis of a slow push-up.

If one were actually doing this to submit a "paper", one would go digital, designing a special set of scales with very fast response times. That, really, is a minor engineering problem easily resolved. Though I doubt there is enough interest for anyone to do it.

9. Aug 25, 2008

### rcgldr

Or the person could just hold the position at the top and bottom of the pushup so the scale readings would stabilize.

10. Aug 25, 2008

### atyy

11. Aug 25, 2008

### pallidin

Good point Jeff, and great link atyy!

"the percentage (60%) is different for everyone. The amount of force necessary to move a lever is dependent upon the distance that the weight being moved is from the fulcrum. In this case, the fulcrum being the toes, a person with a large upper body and chicken legs would need to apply more force to complete a push up than someone with very heavy legs and a small upper body. Thus, there is no single answer that applies."

12. Aug 25, 2008

### Staff: Mentor

Yes, that would be my suggestion. Bathroom scales won't be able to give "dynamic" readings with any accuracy.

If you find the top and bottom readings are significantly different I would suggest just doing a linear interpolation for any intermediate weights needed. Otherwise just use the mean.