In the well-known anime Attack on Titan (AOT), the Survey Corps is the most elite and dangerous military branch, tasked with direct engagement against Titans, studying them, and expanding human territory beyond the walls. To join the Survey Corps, recruits must undergo rigorous physical and mental training, demanding a mastery of advanced mechanics, energy conservation, and From a physics standpoint, passing this training is a significant achievement. This discussion explores the stress on the human body when using ODM gear, using Levi Ackerman as an example.
As a member of the Special Operations Squad, Levi is known for his exceptional combat skills, including his signature high-speed rotational attacks. This discussion involves understanding the conservation of energy, centripetal force, and conservation of angular momentum. The human body’s response to these effects and Levi’s body motion to reduce such effects during the combat are also discussed.
We will use a scenario to do some basic calculations for better understanding.
Levi is swinging between buildings while pursuing a Titan. He hooks onto a 12 m tall building in front of the Titan and jumps 6 m above the ground, creating a pendulum-like swing to gain speed. He must land precisely on the nape of a 15 m Titan, which is 30 m away.
Levi’s mass is 65 kg, and his ODM gear adds 25 kg, making his total mass 90 kg. The cable is attached to a fixed point 6 m ahead, and he starts swinging at an angle of 60° from the vertical. This movement follows a pendulum-like motion, similar to a swing. Ignoring air resistance and by conservation of energy, his speed at the lowest point of the swing, calculated using the formula:
The velocity is approximately 11 m/s.
At the lowest point, Levi experiences centripetal acceleration equal to 9.8 m/s² (also known as 1g, equivalent to the weight experienced by the object on Earth). A centripetal acceleration is an acceleration derived from a centripetal force that helps the object to move in a circular motion. The tension in the cable must support both his weight and the centripetal force, resulting in a total force of 2g acting on him, which is equivalent to twice Levi’s weight.
However, to reach the Titan’s nape, Levi needs a speed of 17 m/s, which gravity alone cannot provide. His ODM gear must generate an additional acceleration of approximately 3g, comparable to that of a roller coaster ride. It would take him 3.5 seconds to reach the Titan at this speed. To cut the time in half, his acceleration must increase, potentially reaching 5g or higher.
To understand how Levi survives these forces, we must now consider the human body’s response to acceleration.
At 5g, breathing becomes difficult, and vision may blur. At 9g, blood is pulled downward, leading to dizziness or even blackouts. Jetfighter pilots need to endure up to 9g but require specialised suits and breathing techniques to remain conscious.
To withstand extreme ODM manoeuvres, Levi must have adapted some special technique to tense his muscles while swinging to maintain blood flow to his brain. Also, do not forget that Levi is from the Ackerman clan, known as the king’s shield and bodyguard; they are physically stronger and more agile.
Knowing Levi’s fighting style, his signature rotational attack is an aerodynamic strategic movement that has a real physics advantage. His spin creates angular momentum, stabilising his movement like a gyroscope and preventing sudden trajectory shifts. According to the conservation of angular momentum, the axis of rotation would remain constant if no external force is applied and resists any change to it, which also helps to stabilise his movement and trajectory. Additionally, such rotational movement distributes g-forces across the body, reducing strain and delaying G-LOC (g-force-induced loss of consciousness).
His rotational attack also redirects the downward force acting on his body, preventing excessive G-force build-up on one side. Like cats that twist mid-air to land safely, Levi’s rotational movement smooths out acceleration changes. Moreover, the build-up of angular momentum enhances his cutting power, much like a rotating saw blade, which delivers deeper, more efficient cuts.
Levi’s combat efficiency is a perfect blend of physics and skill, but achieving such mastery requires immense effort and conditioning. To withstand the extreme forces of ODM manoeuvres, Levi must train his body to endure high g-forces, develop precise timing, and apply optimal trajectory control. His ability to execute high-speed swings, rapid accelerations, and controlled rotations demands physical endurance and technical expertise far beyond that of an average soldier.
By refining his ODM techniques — such as controlled acceleration boosts, optimised anchor points, and improved trajectory planning — Levi could push his agility and lethality even further. His ability to turn physics into an art form makes him the deadliest soldier on the battlefield.
Prepared by:
Tan Kwee Yong
Cover image source: CBR.com
