Does Headgear Prevent Concussion? What the Science Actually Shows
Sports headgear is often promoted as protection, in some cases even understood or believed to be prevention against concussion [1]. Yet many studies and media headlines suggest that headgear does not reduce concussion risk in sport.
The reality is that the efficacy of headgear around concussion and brain injury is more complex.
Some specialist headgear can reduce concussion risk, but only when it addresses the biomechanical forces that cause brain injury during head impacts. But no headgear can prevent concussion, because concussion is a statistical risk. Modern neuroscience and sports biomechanics research increasingly shows that concussion and many other traumatic brain injuries are driven primarily by rotational forces transmitted to the brain during head impacts.
Most traditional non-helmeted sports headgear was not designed or even safety tested to reduce these forces. Instead, traditional non-helmeted sports headgear was originally developed to reduce visible injuries such as cuts, abrasions and cauliflower ear by cushioning linear impact forces at the surface of the head.
This design and functional distinction is critical.
Understanding the difference between head protection and brain protection explains why some headgear appears ineffective in scientific studies, while other technologies demonstrate meaningful reductions in concussion risk both in biomechanical testing and in real world play.
Definition: Brain Protection in Sport
Brain protection refers to protective equipment designed specifically to reduce the rotational forces transmitted to the brain during concussive and sub-concussive head impacts; these forces are the primary biomechanical driver of brain injury in sport.
Rotational forces occur when the head rotates rapidly during an impact. Because the brain is suspended within the skull in cerebrospinal fluid, it briefly lags behind the skull’s motion due to inertia. This creates shear strain within brain tissue.
Research consistently shows that rotational acceleration produces greater deformation of brain tissue than linear acceleration alone, making it a key mechanism in sub-concussion, concussion and traumatic brain injury [2].
Effective brain protection therefore requires equipment designed to reduce rotational force transmission during head impacts.
Head Protection Is Not the Same as Brain Protection
Many sports headgear products were originally designed to protect the scalp and skull rather than the brain itself.
| Head Protection | Brain Protection |
|---|---|
| Designed to reduce cuts, abrasions and surface injuries | Designed to reduce brain injury risk |
| Typically focuses on reducing linear impact forces | Reduces linear forces and, more importantly, rotational forces, the primary driver of brain injury |
| Typically uses foam padding | Uses advanced protective technology engineered for brain safety |
| Protects the surface of the head | Designed specifically to protect the brain |
| Traditional all-head coverage sports headgear | Modern brain protection technology |
Foam padding can reduce linear acceleration of the skull during an impact. However, sub-concussion, concussion and many forms of brain injury are strongly associated with rotational acceleration of the brain within the skull [3]. Padded headgear has limited effect in reducing rotational force transmission.
This means equipment designed primarily to cushion the scalp will have limited ability to address the forces most closely associated with brain injury.
How Different Headgear Designs Compare
Non-helmeted sports headgear for football, rugby, basketball, netball and combat sports varies widely in how it is designed and what it protects. The table below compares commonly used products across different sports.
| Product | Brain Protection | Qualified Rotational Force Reduction | CE / UKCA PPE Classification | Virginia Tech Helmet Lab Rating | Product Specification | Weight | Thickness | Registered Medical Device |
|---|---|---|---|---|---|---|---|---|
| Rezon Halos® | Yes | Yes (up to 61%) | CE / UKCA Category II PPE | 5-Star | Patented Rotection® Technology (learn more) | 70g | 9.5mm | FDA registered |
| N-Pro Scrum Cap | No | Yes (average 34%) | Category II PPE | Not publicly declared | Viscoelastic Foam | 190g | 13mm | No |
| Hedkayse Headguard | No | No | Category I PPE | Not publicly declared | Amnesic Foam | 220g | 11mm | No |
| Storelli ExoShield | No | No | No | 5-Star | Foam padding | 116g | 12mm | No |
| Unequal Halo | No | No | No | 5-Star | Foam padding | 178g | 10mm | No |
| Headstrong Headguard | No | No | No | 5-Star | Foam padding | 190g | 8-17-26mm | No |
| Gamebreaker Aura | No | No | No | 5-Star | Foam padding | 86g | 10mm | No |
| Goldline Head First | No | No | No | Not tested | Foam padding | 300g | 10mm | No |
Most sports headgear relies primarily on foam padding to cushion impact at the surface of the head. While this can reduce some linear force, it may not significantly reduce the rotational forces associated with brain injury. The comparison highlights a fundemental difference between traditional headgear and modern brain protection technology.
What Causes Brain Injury in Sport?
The human brain is a soft organ suspended within the skull in cerebrospinal fluid.
When the head experiences a sudden impact, the skull accelerates rapidly while the brain momentarily lags behind due to inertia. This relative motion causes deformation of brain tissue.
Two types of acceleration occur during head impacts:
Linear acceleration
Straight-line movement of the head where the brain moves in a linear plane.
Rotational acceleration
Angular motion of the head causes the brain to rotate inside the skull.
Biomechanical research consistently shows that rotational acceleration produces greater strain within brain tissue than linear acceleration alone, making it a major driver of concussion and other traumatic brain injuries [4].
During impacts rotational forces cause:
- tearing of tiny blood vessels and brain cells
- resulting, over time, in the breakdown of the blood-brain barrier and
- the creation of damaging neuro-inflammation
Reducing rotational forces to the brain is essential to lower the risk of neuro-inflammation [5].
Why Sub-Concussions Matter
Many head impacts in sport do not produce symptoms of concussion. These smaller force impacts are known as sub-concussions.
A sub-concussion is a head impact of lower force than required to cause a concussion, but it still causes damage to the brain without any symptoms. Sub-concussive impacts are hundreds of times more frequent than impacts which result in concussion.
For example, players of all levels may experience hundreds of sub-concussive impacts across a single season of contact or collision sport [6].
Although an individual sub-concussion may produce no noticeable symptoms (asymptomatic), repeated exposure can produce cumulative neurological effects over time and adversely affect memory, the ability to focus, learn and think as well as behaviour. Research increasingly links repeated sub-concussive impacts with long-term brain injury risk and neurodegenerative conditions such as chronic traumatic encephalopathy (CTE) [7].
How Headgear Is Tested for Concussion Protection
Protective sports equipment is sometimes tested using biomechanical impact testing.
In these tests, instrumented headforms measure the acceleration experienced by the head during controlled impacts. These measurements allow researchers to estimate the risk of concussion based on known biomechanical thresholds and using data points.
The Virginia Tech Helmet Lab has developed a globally recognised and peer reviewed rating system that evaluates protective equipment based on its ability to reduce both linear and rotational acceleration.
Products are assigned a STAR rating from 1 to 5, with higher ratings indicating lower predicted concussion risk.
Virginia Tech recommends 4-Star and 5-Star rated equipment as the most effective options for reducing concussion risk. To date, no World Rugby-approved scrum caps have declared a 4- or 5-star rating [8].
Why Some Studies Suggest Headgear Does Not Work
A widely discussed and cited randomised controlled trial with x participants examining headgear concluded that protective headgear did not significantly reduce concussion incidence among adolescent players [9].
However, closer examination of the study results reveals an important point of detail.
Approximately 60% of players in the trial wore lower-rated 3-Star headgear, while only around 40% wore higher-rated 5-Star products.
Virginia Tech’s rating system recommends only 4-Star and 5-Star equipment for meaningful concussion risk reduction.
Within the study results, the highest-rated headgear demonstrated a statistically significant reduction in concussion risk, with risk ratios suggesting reductions of approximately 60% compared with players wearing no headgear. No headgear eliminated concussion risk, but higher-rated headgear demonstrated lower relative risk.
This finding highlights a key point:
The effectiveness of sports headgear to reduce concussion risk depends heavily on how the equipment is designed, not simply whether headgear is worn or not.
Why Rezon Halos® Is Different
Most sports headgear relies on foam padding designed primarily to cushion surface impact.
Rezon Halos® was engineered specifically to address the rotational forces associated with brain injury.
Halos® uses a proprietary multi-layer system known as Rotection® Technology, in which nine independently moving protective layers dissipate energy during concussive and sub-concussive head impacts.
Independent biomechanical testing using the Virginia Tech Helmet Lab methodology demonstrates that Halos® can reduce rotational force transmission by up to 61% while reducing concussion risk by approximately 74%.
Unlike traditional padded headgear designed primarily to protect the scalp, Halos® was designed from the outset as brain protection technology.
Why Children and Women May Face Higher Brain Injury Risk
Brain injury risk in sport can affect all players at every level of the game, but does not necessarily affect all individuals equally.
Children’s brains are still developing throughout late childhood and adolescence. Neural pathways and supporting structures continue to mature during this period, potentially making the brain more susceptible to injury from repeated head impacts.
Children also have a longer potential exposure window to head impacts and brain injury through sport, meaning cumulative exposure to sub-concussive impacts occurs over many years of play.
Research also suggests that female athletes experience higher concussion rates in several sports compared with male athletes, possibly due to differences in neck strength, head-to-body mass ratio and hormonal factors [10].
Reducing exposure to rotational forces and cumulative sub-concussive damage early in life can play an important role in protecting long-term brain health.
What is the difference between head protection and brain protection?
Head protection reduces surface injuries such as cuts and abrasions. Brain protection refers to equipment designed specifically to reduce the rotational forces that are the primary driver of brain injury in concussive and sub-concussive impacts.
Headgear can reduce concussion and sub-concussion risk when it is specifically designed to address the rotational forces that cause brain injury.
Traditional sports headgear was largely designed to reduce cuts and abrasions rather than reduce the rotational forces associated with brain injury.
Modern protective technologies are beginning to address this challenge by designing equipment specifically to reduce rotational forces transmitted to the brain.
As scientific understanding of brain injury continues to evolve, the distinction between head protection and brain protection is becoming increasingly important for players and athletes across many sports.
Frequently Asked Questions
👉 Learn more about Rezon Halos® and evidence-based brain protection in sport here.
- Rezon Survey on brain injury awareness. Further Reading. Rezon.
- Predictors for traumatic brain injuries evaluated through accident reconstructions. Kleiven. 2007.
- Biomechanical investigation of head impacts in sport. C Withnall, N Shewchenko, R Gittens, J Dvorak. British Journal of Sports Medicine.
- Biomechanics and neuropathology of adult and paediatric head injury. Ommaya, Goldsmith, Thibault, 2009.
- Brain Injury Science. Further Reading. Rezon.
- Subconcussive Head Impact Exposure and White Matter Tract Changes over a Single Season of Youth Football. Naeim Bahrami, Dev Sharma, Scott Rosenthal, Elizabeth M. Davenport, Jillian E. Urban, Benjamin Wagner, Youngkyoo Jung, Christopher G. Vaughan, Gerard A. Gioia, Joel D. Stitzel, Christopher T. Whitlow, and Joseph A. Maldjian, 2016.
- Leveraging football accelerometer data to quantify associations between repetitive head impacts and chronic traumatic encephalopathy in males. Daneshvar DH, Nair ES, Baucom ZH, Rasch A, Abdolmohammadi B, Uretsky M, Saltiel N, Shah A, Jarnagin J, Baugh CM, Martin BM, Palmisano JN, Cherry JD, Alvarez VE, Huber BR, Weuve J, Nowinski CJ, Cantu RC, Zafonte RD, Dwyer B, Crary JF, Goldstein LE, Kowall NW, Katz DI, Stern RA, Tripodis Y, Stein TD, McClean MD, Alosco ML, McKee AC, Mez J, 2023
- What is the best protective headgear for Rugby players? Further Reading. Rezon.
- Does soccer headgear reduce the incidence of sport-related concussion? A cluster, randomised controlled trial of adolescent athletes. British Journal of Sports Medicine. McGuine T, Post E, Pfaller AY, Hetzel S, Schwarz A, Brooks MA, Kliethermes SA. 2000.
- Sex differences in the extent of acute axonal pathologies after experimental concussion. Song H, Tomasevich A, Paolini A, Browne KD, Wofford KL, Kelley B, Kantemneni E, Kennedy J, Qiu Y, Schneider ALC, Dolle JP, Cullen DK, Smith DH, 2024
Author: Alex Reily
