T Nation

Theory on Strength and Gravity

I was watching a show on the Travel Channel last week and it showed an Ecuadorian woman balancing an egg on a pin. She explained she was able to do this because the gravity is less at the equator (the gravity is less due to something called equatorial bulge; the distance from the Earth’s surface to the center of the Earth is larger at the equator, hence less gravity.)

Naturally, I started thinking about the implications for powerlifting and strength and it occurred to me that people who live near the equator have to overcome less gravitational forces and as a result, perhaps develop less musculature. An analogy might be a horse that carries a 100 pound load up a hill every day will get stronger than one carrying an 80 pound load.

Granted, the gravity difference is small, but it was mentioned that your weight is a kilo or 2 less at the equator, which certainly is not a trivial effect.

Maybe this explains why Scandinavian people, people who live at extremely high latitudes and hence higher gravity, dominate strength sports. Just a thought-anyone else agree?

Very interesting idea. I don’t disagree that it is a possibility. It would for sure be a very interesting study for an anthropologist to perform. I know I’d watch the PBS special on it.

Although gravity maybe slightly less, and you may weigh less, your mass isn’t affected. So it would be impossible to “weigh” 2 kilos less. A kilogram is a measure of mass, so your mass is the same on the moon as on earth.

Your weight is mass x gravity. So take a person who has 100kg of mass. As you stated, at the pole he may weigh 4 pounds more.

Pole person = 220 pounds
equator person = 216 lbs

The 4 lbs difference in weight would be divided over your entire body, so i doubt you would even notice the effect.

HOWEVER, the whole thing is inconsequential because you probably wouldn’t weigh more at the poles. You actually weigh less as you approach the center of the earth, and at the center you would be weightless because you have the mass of the earth pulling on you from all directions.

If you could survive at the center of the earth, you would levitate and every direction would be “up”. So the word of an egg balancing village person means little to the laws of physics. balancing objects has to do with the center of gravity, weight has little affect anyways unless is was so heavy you couldn’t lift it.

HOWEVER, will the distance change be offset of magnitude of acceleration. Gravity is measured from the “center of mass” of objects. Because the earth rotates, you accelerate toward the center, in this case the earth’s axis and center of mass.

Weight equals mass x gravity (acceleration toward the center of an object, in this case the earth). When the earth is spinning, you have gravity and circular acceleration acting on you. at the axis, you would just have gravity, because you are on the exact axis of spinning.

To solve this dilemma you would need to weigh yourself at the equator and the True north, not the north pole. Then you would have your answer. There are so many variables in this equation you would need to account for everything. I’m sure someone somewhere has calculated it out, but it needs more proof than a balancing egg.

please correct me if i’m wrong. It’s friday evening and i’m just getting off work, i really didn’t have much time to think about it.

[quote]SamuraiWannaBe wrote:
Very interesting idea. I don’t disagree that it is a possibility. It would for sure be a very interesting study for an anthropologist to perform. I know I’d watch the PBS special on it.[/quote]

Indeed. I’d definitely tune in.

would that mean that it would require less energy to lift the same amount of weight, thus higher 1RM?

Maybe that’s way all those Scandavians are tearing up strongman…

[quote]baretta wrote:
Although gravity maybe slightly less, and you may weigh less, your mass isn’t affected. So it would be impossible to “weigh” 2 kilos less. A kilogram is a measure of mass, so your mass is the same on the moon as on earth.

Your weight is mass x gravity. So take a person who has 100kg of mass. As you stated, at the pole he may weigh 4 pounds more.

Pole person = 220 pounds
equator person = 216 lbs

The 4 lbs difference in weight would be divided over your entire body, so i doubt you would even notice the effect.

HOWEVER, the whole thing is inconsequential because you probably wouldn’t weigh more at the poles. You actually weigh less as you approach the center of the earth, and at the center you would be weightless because you have the mass of the earth pulling on you from all directions.

If you could survive at the center of the earth, you would levitate and every direction would be “up”. So the word of an egg balancing village person means little to the laws of physics. balancing objects has to do with the center of gravity, weight has little affect anyways unless is was so heavy you couldn’t lift it.

HOWEVER, will the distance change be offset of magnitude of acceleration. Gravity is measured from the “center of mass” of objects. Because the earth rotates, you accelerate toward the center, in this case the earth’s axis and center of mass.

Weight equals mass x gravity (acceleration toward the center of an object, in this case the earth). When the earth is spinning, you have gravity and circular acceleration acting on you. at the axis, you would just have gravity, because you are on the exact axis of spinning.

To solve this dilemma you would need to weigh yourself at the equator and the True north, not the north pole. Then you would have your answer. There are so many variables in this equation you would need to account for everything. I’m sure someone somewhere has calculated it out, but it needs more proof than a balancing egg.

please correct me if i’m wrong. It’s friday evening and i’m just getting off work, i really didn’t have much time to think about it.[/quote]

The weight versus mass issue is nitpicking; the point is that the force of gravity is less at the equator. Of course you won’t notice a few kilo difference, but over the course of a lifetime, differential muscular adaptation as a result of latitude differences might be significant.

Interesting theory. Unfortunately, the variation in g (the acceleration due to gravity) is too small to make that much difference. The value of ?g? varies from 978.281 at Chennai (near the equator) to 982.273 at Reykjavik in Iceland (near the north pole).

Translated into the effect on your weight, if you weighed 97.8 kg wt at Chennai, you would weigh 98.2 kg wt at Reyykjavik. You could gain more weight by eating a steak.

[quote]sharetrader wrote:
Translated into the effect on your weight, if you weighed 97.8 kg wt at Chennai, you would weigh 98.2 kg wt at Reyykjavik. You could gain more weight by eating a steak.[/quote]

or lose more with big poop

nice theory but completely off because the difference is trivial and the human body does not respond to a tiny difference over a lifetime. The human body respond to progressive overload over a period of 2-3 weeks with a backoff period, or something similar.

move someone from the equator to the pole and in 2 weeks they have done all the adapting they are ever going to do and it is going to be absolutely microscopic.

thousands of other factors come into play

and there are some big people at the equator, too

Interesting but the physics doesn’t really pan out. The gravitational constant is 6.67E-11Nm^2/kg^2. The force of gravity = Gravitational Constant x (m1 x m2)/r^2. With the massive mass of the earth and the very small mass of a person and the extremely small variation in the diameter of the earth the gravitational force is barely different.

And weight is a force. That would be Newtons. Kg is a mass, not a weight. Newton = Kg x Gravity. The weight of the lifter involved would change slightly, but not the mass.

But this example would be like saying does the 5mm heel out perform the 6mm heel in bench. It just doesn’t really matter.