Physics puzzle: chin-ups.

[pzhon]

Suppose I weigh 200 pounds and can perform a set of 10 chin-ups. What weight of dumbell should you expect me to be able to curl 10 times?

[billygrippo]

well these are not all the same musscles at work here.

[pzhon]

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well these are not all the same musscles at work here.

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Right, not all are the same. The chin-up uses back muscles, too. What component of the chin-up comes from using the muscles involved in a curl?

[billygrippo]

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[ QUOTE ]
well these are not all the same musscles at work here.

[/ QUOTE ]
Right, not all are the same. The chin-up uses back muscles, too. What component of the chin-up comes from using the muscles involved in a curl?

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i have no idea.

this is more of a personal trainer question than a physics one.

[Central Limit]

people who are very thin can often do many chin-ups but not curl very much.

[billygrippo]

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people who are very thin can often do many chin-ups but not curl very much.

[/ QUOTE ]

youre a genius.

[mostsmooth]

[ QUOTE ]
[ QUOTE ]
well these are not all the same musscles at work here.

[/ QUOTE ]
Right, not all are the same. The chin-up uses back muscles, too. What component of the chin-up comes from using the muscles involved in a curl?

[/ QUOTE ]
underhand chinups, as in your palms would be facing you.

[pzhon]

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i have no idea.


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So why post?

[ QUOTE ]
this is more of a personal trainer question than a physics one.

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It is a physics problem with applications to other areas. While I might get better feedback by asking experienced physical trainers, this has applications to bar bets, too. If you see that someone can't quite curl 75 pounds, is it safe to bet that he can't do a 1-handed chin-up?

[billygrippo]

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If you see that someone can't quite curl 75 pounds, is it safe to bet that he can't do a 1-handed chin-up?

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i would say no, and 1 handed chin ups are absurdly hard.

[hmkpoker]

Surprisingly different exercises. It depends on how strong your biceps are vs how strong your lats are.

I can do chinups till kingdom come, but I have no biceps and I can't curl worth a damn.

[Central Limit]

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people who are very thin can often do many chin-ups but not curl very much.

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youre a genius.

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True, but irrelevant.

[CollegeKid]

I'm gonna say 40 lb dumbbells bob.

[SBR]

[ QUOTE ]
Suppose I weigh 200 pounds and can perform a set of 10 chin-ups. What weight of dumbell should you expect me to be able to curl 10 times?

[/ QUOTE ]

Impossible to know.

[Aver-aging]

This is a biology problem, not a physics problem.

[pzhon]

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Impossible to know.

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Really?

Suppose I have an accident and my biceps are cut. Do you think I could still do a chin-up? I hope not. Ok, what if this reduced the strength of my biceps to 10 pounds maximum? 20?

Ok, when you do a chin-up, focus on your biceps. How much does it feel like you are curling? Why? (The answer to the why is basic physics.)

These are the types of things I expect people to think through before posting. If you can't be bothered to think about it, why post?

[billygrippo]

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[ QUOTE ]

Impossible to know.

[/ QUOTE ]
Really?

Suppose I have an accident and my biceps are cut. Do you think I could still do a chin-up? I hope not. Ok, what if this reduced the strength of my biceps to 10 pounds maximum? 20?

Ok, when you do a chin-up, focus on your biceps. How much does it feel like you are curling? Why? (The answer to the why is basic physics.)

These are the types of things I expect people to think through before posting. If you can't be bothered to think about it, why post?

[/ QUOTE ]

there simply isnt enough info to make an accurate guess.

[evolvedForm]

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If you see that someone can't quite curl 75 pounds, is it safe to bet that he can't do a 1-handed chin-up?

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Nope. I can do a one handed chin-up, but I'm not even close to curling 75 pounds (with one hand at least). More like 50 for a 1-rep max when I'm in good shape.

As for your problem, it seems impossible to measure accurately. There are too many factors, one of which is how proficient the individual lifter is at the chin-up versus the curl. This fact throws off your whole study, since it is dependent on the subject. You might be able to figure out some reasonable range, however. To do that would probably take experiments, though. This cannot be determined conceptually.

[gumpzilla]

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This cannot be determined conceptually.

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He isn't looking for some kind of rigorous proof of an exact number which doesn't even necessarily exist. I would assume he's looking for some kind of argument, based on some reasonable physical assumptions, to make an educated guess. This kind of thing is interesting in its own right.

pzhon, it's an interesting question. I'll think about it for a bit.

[Green Kool Aid]

the title is hilarious.

and im sure there is a correlation between the two with a pretty large variance, but its not even close to a physics "puzzle." lol

[gumpzilla]

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and im sure there is a correlation between the two with a pretty large variance, but its not even close to a physics "puzzle." lol

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I don't do this all too often, but I'm going to pull rank on you here. Just because this isn't a textbook problem with a clear cut answer doesn't mean it's not an interesting question. (In reality, textbook problems with clear cut answers are usually the least interesting questions.) pzhon is a mathematician. I'm a physicist. We both seem to think that it is an interesting question. Perhaps that should be given some weight in this instance.

[evolvedForm]

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This cannot be determined conceptually.

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He isn't looking for some kind of rigorous proof of an exact number which doesn't even necessarily exist. I would assume he's looking for some kind of argument, based on some reasonable physical assumptions, to make an educated guess. This kind of thing is interesting in its own right.

pzhon, it's an interesting question. I'll think about it for a bit.

[/ QUOTE ]

I don't see how the educated guess could be very accurate considering the subjective nature of physical training. Think about this: a person is well-trained in curling but poorly trained in chin-ups. This will make a huge difference in the results. I know from experience that the body adapts to specific motions. One person's body may adapt better to one than another.

This is why the impossibility of finding an answer. I agree it was interesting too, until I thought of this roadblock.

[traz]

There isn't much correlation between vicepts and chin-ups. There's obviously some..but your example is flawed. If your biceps were severely injured you wouldn't be able to do many things, not just chin-ups.

Its the same thing with push-ups...many people think pushups are some kind of indication of bicep strength.

[benkahuna]

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There isn't much correlation between vicepts and chin-ups. There's obviously some..but your example is flawed. If your biceps were severely injured you wouldn't be able to do many things, not just chin-ups.

Its the same thing with push-ups...many people think pushups are some kind of indication of bicep strength.

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Many people seriously believe that?

Morons. Obviously, push-ups are more reliant on extensor muscles in the upper arm (triceps) and pectoral muscles. Biceps are necessary for a smooth downward motion toward the ground, but their use is clearly minimal in that calisthenic (sic).

What gets sore when you do push-ups? Exactly...