Do Scrum Caps Prevent Concussion?

What scrum caps are designed to do

Padded scrum caps or headguards are soft coverings worn to protect the scalp and ears.

Their design and purpose is limited to preventing superficial injuries such as cuts, abrasions, and cauliflower ear. By purpose, they are not intended to protect the brain, nor to reduce the rotational forces in concussive or sub-concussive brain injury ^[3].

As a result, the presence of a scrum cap on a player or the marketing positioning of headguards does not indicate meaningful brain protection, albeit they may reduce visible injury or the pain from heavier impacts.

What World Rugby Regulation 12 actually says about headgear

World Rugby Regulation 12 explicitly defines the purpose and limitations of approved rugby headgear.

It states that headgear:

• is not intended nor expected to protect against concussion or mild traumatic brain injury
• is designed only to protect against cuts, abrasions, and superficial injuries
• has limited impact attenuation properties by design ^[3]

Regulation 12 also places strict constraints on design, including limits on padding thickness and material density. Most conventional rugby headguards are constructed from a single thin layer (typically around 10 mm) of lightweight, closed-cell foam and are restricted to a maximum density of 45 kg/m³ ^[3].

Because of these constraints, headgear designed and approved under World Rugby Regulation 12 is not intended nor expected to reduce brain injury or concussion risk. Yet “protection” is marketed by manufacturers, with scrum caps and headguards often purchased with the expectation of protection against head injury by players and parents.

World Rugby has developed a Law 4 trial process to enable the assessment of rugby headgear, which, according to the manufacturers, has been designed to achieve specific, quantifiable medical purposes ^[4]. This specification uses Regulation 12 as a base specification with variations which do not increase the onerousness of the tests or the requirements from Regulation 12. Consequently, the Law 4 trial testing does not increase the protective performance requirements beyond those set out in Regulation 12.

Additionally, the position of the MHRA and EU Commission under the Borderline Manual ^[4] determines that a rugby helmet in the UK and EU cannot be considered as having ‘medical purposes’.

Why “impact force reduction” claims miss the point

Many headgear brands promote claims such as “reduces impact,” “absorbs impact forces,” or “advanced impact protection.” These statements typically refer to linear forces, which describe straight-line acceleration of the skull.

Modern brain injury science shows that this framing is incomplete and misleading. Linear forces primarily affect the skull, whereas brain injury is driven primarily by rotational forces, which cause the brain to rotate inside the skull ^[5].

Rotational forces generate shear strain within brain tissue, tearing fine blood vessels, disrupting neural networks, damaging the blood–brain barrier and creating damaging neuro-inflammation. This explains why concussion and sub-concussion can occur in the absence of physical head injury.

Reducing linear impact force alone does not translate to reduced brain injury risk.

Furthermore, when tested under the Virginia Helmet Lab methodology, the global gold standard for head protection testing, products claiming significant ‘impact reduction’ have been proven to demonstrate only limited performance in reducing concussion risk.

Why conventional padding cannot control rotational forces

Conventional rugby headgear relies on surface foam padding. Padding can reduce cuts and abrasions and may lower peak linear acceleration, but it has limited ability to reduce rotational forces.

In some cases, padding may even increase rotational torque due to added mass, increased surface area, and additional catch points during angled impacts ^[6].

Biomechanical research consistently shows that rotational acceleration/force is more strongly associated with brain injury than linear acceleration alone ^[4]. Repetitive head impacts involving rotational acceleration are increasingly associated with increased risk of developing CTE, a progressive neuro-degenerative disease that leads to early-onset dementia ^[7].

Do viscoelastic foam headguards solve this problem?

Viscoelastic foam represents an improvement over basic padding in headguards, but it has limited ability to meaningfully reduce rotational forces.

Higher-density, viscoelastic, open-cell foams dissipate energy through deformation and viscous air movement within the foam structure. These materials can reduce peak rotational velocity (PRV) and maximal principal strain (MPS), both of which are biomechanical measures associated with brain injury risk ^[7,8].

Independent testing reflects these limitations. Virginia Tech Helmet Lab testing shows that N-Pro, a layered viscoelastic foam-based headguard, reduces rotational forces by an average of 34%, significantly less than the at least 60% reduction in rotational force offered by Rezon Halos® ^[9].

Why Rezon Halos® is fundamentally different

Rezon Halos® is not padded headgear. It is brain protection, designed from the outset with this distinct protective objective.

Halos® uses a patented technology called Rotection®, which is designed specifically to reduce rotational forces being transmitted to the brain.

Rotection® is a multi-layered system in which nine independently moving protective layers dissipate rotational energy. Halos® reduces the transmission of rotational forces, rather than simply cushioning the scalp.

This is a mechanically different approach to brain protection in sporting headgear, not an incremental refinement of padding.

Independent testing by the Virginia Tech Helmet Lab shows that Rezon Halos® reduces rotational forces by at least 60% and reduces concussion risk by 74% ^[9]. Halos® is the only non-helmeted head worn protection to achieve both a Virginia Tech 5-Star safety rating and CE / UKCA Category II PPE certification.

No World Rugby-approved scrum cap has publicly disclosed a 4 or 5-star Virginia Tech rating. Virginia Tech recommends only products achieving 4 or 5 stars.

This is why World Rugby approval is not the same as brain protection: approval determines what may be worn in competition, not whether a product meaningfully reduces rotational-force transmission.

Why this matters for rugby players

Rugby exposes players from a young age to repeated head impacts throughout training and matches. The majority of these impacts are sub-concussive, small-force impacts producing no concussion symptoms but still transferring damaging rotational forces to the brain.

Over time, the cumulative damage of rotational forces and sub-concussions is associated with brain tissue damage, neuro-inflammation, and increased long-term neurological risk, including CTE, MND and Parkinson’s. This is even the case for players who have never been diagnosed with a concussion ^[10].

Reducing rotational force transmission in concussive and sub-concussive impacts is therefore central to reducing brain injury risk for all players in rugby.

A child’s brain is even more susceptible to rotational forces and cumulative sub-concussions. It is unknown in childhood if genetic or metabolic risk factors exist, and an individual’s length of playing career, meaning every child is at risk of a potentially massive lifetime dose of rotational forces and sub-concussions.

Key takeaway

This is why Rezon Halos® performs differently, and outperforms every World Rugby approved headguard tested for rotational force reduction.