Previously I discussed the positives and negatives of training with wearable weights, as seen in martial arts anime. However, there is another type of training found in shounen anime and that is the gravity training popularized by Dragon Ball Z. Instead of training with body weights the characters train in heavier than earth gravity, which is created artificially in a specialized room in most cases.
Warning Astrophysics Content
Gravity is one of the four fundamental forces of the universe, and it is the attraction of objects with mass towards each other. Every object that has mass, from the sun and planets to small specks of dust, exhibits gravity, but the larger the object, the more gravity it has. (Realistically, we only worry about gravity from celestial objects like stars, planets, and moons, and not our cars and backpacks.) The distance between objects also matters when talking about gravity: the closer they are, the stronger the force of gravity is, and the further apart they are, the weaker the force of gravity is. This is why we are pulled down by gravity on the surface of the Earth, but we can float if we are in a spacecraft orbiting Earth.
But what causes gravity in the first place? First let’s think of the universe as a giant blanket called spacetime.
This blanket is all of the space in the universe, but what about the matter or stuff in the universe? Matter as I first describe it to my students is stuff that takes up space, and this is what happens when it is placed on our spacetime blanket.
See how the matter deforms the blanket, creating an indent in spacetime, and the bigger the object, the bigger the indent. The size and slope of the indent represents gravity. Now imagine that the yellow ball is the Earth. If you are at the bottom, the slope is very hard to climb up, but once you get up the hill, the slope almost disappears, meaning there is much less gravity. This is essentially what happens when you go into space, you travel past the steepest part of the slope and the pull of Earth’s gravity is greatly reduced.
FYI- the gravitational pull does vary slightly across the surface of the earth, maxing out at 9.83m/s^2 at the poles, and a minimum of 9.76m/s^2 at the equator, with an average amount of 9.8m/s^2 (1g) everywhere else.
Astrophysics content over
I am not going to get into the physics of how an artificial gravity machine might work at this time, and instead focus on how gravity training, specifically in gravity higher than Earth’s gravity might affect the body. The idea behind high gravity training as explained in the show is that it is more effective than wearing weighted clothing as it can train the entire body instead of just the muscles. Now according to the Dragon Ball wiki, Vegeta weighs 123lbs, so when he is training in the gravity room at 400G his body now feels like it is 49,200lbs or 24.6 tons (greyhound bus). I think we can all agree this is insane, even for a human-like alien that can turn into a giant monkey.
Human response to high gravity
While it is impossible to make a gravity chamber like what we see in Dragon Ball Z, there are situations where regular humans can experience higher than normal gravity. This occurs due to certain types of movement, specifically high-speed acceleration. One such example is when you are driving your car and hit the accelerator to quickly merge onto the highway, pushing you into the back of your seat. Another example would be the feeling of your stomach being pulled towards your feet while on a roller coaster.
This type of high gravity exposure is called positive G force, and the average person can only handle about 5.5G’s before passing out. This occurs in stages and is due to gravity pulling the blood in the body towards your feet and away from the brain.
Grey out- Loss of color vision as blood flow to the retina is reduced
Tunnel Vision- Loss of peripheral vision as blood flow to the retina is severely reduced
Blackout- Loss of vision as blood flow to the retina is cut off.
G-LOC- Gravity induced loss of consciousness due to a lack of blood flow to the brain.
Death- Due to a lack of blood flow to the brain, heart, and lungs.
A normal untrained person can sustain anywhere from 4 to 6 times the normal force of gravity for a short period of time without passing out, depending on the cause of the force. Trained individuals with the right equipment can handle up to 9 times the force of gravity without passing out. FYI- the position you are in while experiencing the force matters.
A prone position is the easiest position to be in when exposed to high gravity because gravity cannot pull all of the blood to your feet when lying on your stomach. It makes sense that Goku is laying down to recover while after some gravity training.
The other type of G forces a person can experience are negative G’s and that is the feeling of all of the blood rushing to your head. You can experience this at certain amusement park rides or simulate it by doing a head stand for a short period of time. Sadly, the human body’s resistance to negative G’s is much less as you will pass out after 2-3 negative G’s. Also, all of the blood rushing to your head floods the brain with too much blood, overloading the vessels and potentially causing them to burst, causing a hemorrhagic stroke.
Slightly more realistic gravity training
Leaving aside how you might create a high gravity environment, let’s take a look at what might be considered a slightly more normal approach to high gravity training. Now let me start by saying there will a lot of conjecture on my part here as there is no way to perform experiments on this particular topic.
First off let’s go with a more modest high gravity situation, say 1.25-1.5G’s. This means your body feels 25%-50% more than it would otherwise. To begin with, everything that occurs during body weight training would occur here. As a result, I would recommend only spending small amounts of time working out at higher gravity and not living in it all the time.
Theoretically if you spent more time in a high gravity environment or trained at higher amounts of gravity, then there are some other side effects that might occur. The first is high blood pressure, which might not make sense, but let’s think about it, more gravity makes the blood heavier, meaning the heart has to work harder to pump it through the blood vessels. This would result in the blood being at a higher pressure. While it is a relatively silent condition, meaning that it doesn’t have readily observable symptoms, over time it will damage an individual’s cardiovascular system.
The next potential issue is restrictive cardiomyopathy, which is when the heart cannot fill with blood, meaning less blood is being pumped each time the heart beats. This means the heart has to beat more often to maintain blood flow around the body. Typically, this is caused by stiff heart muscle that has trouble expanding.
In our case the higher gravity is pulling the blood to your feet, meaning that it isn’t flowing into the heart. The resulting symptoms include:
Shortness of breath
Oh, and a person with this condition is restricted when it comes to exercise and no weight lifting.
The final possible condition caused by training in high gravity is left ventricular hypertrophy, which is an overgrowth of heart muscle. Normally an increase in heart muscle can be a good thing, but in some cases the muscle grows on the inside of the heart instead of the outside shrinking the volume of the ventricle (Asymmetric Septal Hypertrophy).
The condition can be genetic and/or it can be a maladaptation to exercise, meaning that the body adapts in the wrong way to exercise. The symptoms include:
Shortness of breath
While it does involve more than a little scientific speculation, I am going to call gravity training busted, on the grounds that while it might make you stronger, gravity training is going to damage other parts of your body and potentially kill you.