The Clinic is our playbook – a place to learn about engineering, medicine, and other issues pertaining to sports protection and performance.
What is a concussion?
A concussion is a brain injury caused by an impact to the head or body, making the brain move back and forth quickly inside the skull. Researchers do not fully understand the causes of concussion.
What is CTE?
Chronic Traumatic Encephalopathy (CTE) is thought to result from repeated blows to the head over time, causing progressive damage to nerve cells in the brain. Researchers do not fully understand CTE’s prevalence or causes.
The causes of concussion and CTE remain inconclusive. While it is thought that reducing impact forces has a positive affect, this link has not yet been scientifically established. No helmet can eliminate brain injury, but all helmets are not created equal.
Newton’s Laws of Motion
Isaac Newton’s three laws of motion were first compiled in 1687. The second of those laws governs football collisions:
FORCE = MASS x ACCELERATION
A helmet’s job is to reduce the FORCE from a collision before it can reach the player’s head and brain. The player’s MASS cannot change, so in order to reduce FORCE one must reduce ACCELERATION.
There are two primary types of ACCELERATION resulting from a football collision:
- LINEAR ACCELERATION, which results from a straight ahead collision
- ROTATIONAL ACCELERATION, which results from a glancing blow or twisting motion
Physics and The ZERO1
The VICIS ZERO1 is a 21st century helmet that employs several longstanding principles in physics, starting with Newton’s 2nd Law from the 17th century.
The ZERO1’s RFLXTM layer leverages a sophisticated construction of columns that bend and flex in response to linear and rotational impacts. The behavior of columns in response to axial load was first described by Swiss physicist and mathematician Leonard Euler in the 18th century.
The ZERO1’s ARCHTM shell is designed to spread force from impact over a broad area in order to reduce risk of head injury. Its name was inspired by arches used throughout the Roman empire and in architecture dating back to 2000 BCE.
To measure the effectiveness of helmets, researchers look at PEAK G and SEVERITY INDEX:
What is PEAK G?
PEAK G is the highest G-Force (multiples of gravity) measured during a head impact.
What is SEVERITY INDEX (SI)?
SI is a method for determining a helmet’s ability to reduce impact forces to the head, integrating acceleration over time.