What the CTE Crisis Reveals About Repeated Sub-Concussions in Sport
Nick Lowden’s death should change the way sport thinks and talks about brain injury. More so it should be a wake up call for parents, players, clubs and schools across Australia and beyond.
Nick died aged 23. He is the youngest Australian Rules player to be diagnosed with chronic traumatic encephalopathy (CTE). His parents have spoken publicly about the hits and collisions that he accumulated through the sport he loved [1].
This is tragic. But it is not isolated.
ABC’s Four Corners investigation reports that 33 Australian Rules footballers have now been diagnosed with CTE by the Australian Sports Brain Bank, including 19 professional and semi-professional players. The findings include high-profile players who died in their 20s, 30s and 40s. They also include younger and amateur-level footballers [2].
That matters, because this is not an issue limited to the professional field. Every player exposed to repeated sub-concussions is at risk of CTE, and the younger the player, the greater that risk is.
The brain does not care whether the impact happens in an AFL stadium, on an international field, or on a local junior pitch. It does not recognise the sport, status, selection, contracts or ambition. The brain responds to the rotational forces it is subjected to [3, 4].
This is not only an AFL issue. It is a further warning for every contact, collision and combat sport globally.
This is not a concussion crisis
Sport and governing bodies still talk about brain injury as if concussion is the only and indeed the central problem.
Concussion is important. It must be recognised. Players must be removed from play. Return-to-play rules must be followed. Sport must acknowledge increased brain injury risk in the months following concussion [5].
But concussion is not the biggest risk.
The deeper issue is repeated sub-concussions. These are small-force impacts that do not cause concussion symptoms. They do not stop play. They do not trigger a sideline assessment. They do not appear in concussion statistics [6, 7].
But they still transmit damaging rotational forces to the brain.
If sport only responds when concussion symptoms appear, then sport is only responding to the visible part of the problem. It is missing the silent damage to the brain that builds through the small-force impacts in training, tackles, collisions, falls, heading, marking contests and routine gameplay.
Head impacts do not need to cause symptoms to matter [8, 9].
Rotational forces are the most important factor
The most important biomechanical factor in sports brain injury is rotational force. Rotational kinematics are a stronger indicator of traumatic brain injury risk than linear acceleration [3].
In sport, head impacts are rarely clean, straight or purely linear. They are angled. The head is hit, twisted, stopped, accelerated or decelerated. That movement causes the brain to rotate inside the skull [3, 4].
This is associated with 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.
Brain injury is biomechanical before it is medical.
This is why traditional thinking about head protection is no longer relevant. Protecting the scalp, ears or skull is not the same as protecting the brain. Effective brain protection must reduce the rotational forces that reach the brain during concussive and sub-concussive impacts [3, 4, 11].
CTE risk starts in youth sport
CTE and the risk of neurodegenerative disease does not begin at the AFL draft. It does not begin when a player becomes professional. It begins when the player is first exposed to repeated sub-concussions; meaning it starts in youth sport.
That is one of the most important lessons from the AFL CTE media coverage. The Australian Rules players diagnosed with CTE include professional, semi-professional and amateur-level players. The expert concern is that CTE is being diagnosed in younger footballers, including those who played at amateur levels [2].
But the increased risk profile in youth sport, when the brain is still in peak development, has been clear for years.
This should matter to every parent, coach, school and governing body.
Children and adolescents are not smaller adults. Their brains are still developing. Key neural pathways and protective structures are still maturing. Repeated rotational forces during this period should not be treated as routine, harmless contact [13, 14].
This is not a reason to remove children from sport. Sport matters. Team sport matters. Physical activity matters.
But adults have a duty to reduce sub-concussive brain injury exposure in youth sport.
Is AFL safe?
AFL is a collision sport. It cannot be made risk-free and this is the same for other contact and collision sports.
The serious question is actually whether AFL and other sports more broadly are doing enough to reduce sub-concussive brain injury exposure, and as early as possible.
The answer to this cannot be solved by concussion protocols.
The AFL says that player health and safety is its highest priority and that it has made more than 30 rule changes over more than a decade [1]. Those steps matter. Dangerous tackles should be penalised. Concussed players should be removed. Return-to-play rules should be enforced. But none of those changes moves the needle on sub-concussive damage and CTE risk.
If a sport continues to expose players to repeated rotational forces through sub-concussive impacts that do not cause symptoms, then a symptom-led safety model is incomplete and inadequate.
The more intelligent question is whether sport can reduce repeated sub-concussive brain injury and rotational force exposure from the earliest years of play.
Symptom recognition is not brain protection
Most of the sports safety conversation still happens after concussion.
These measures are not protection.
Australian youth and community concussion guidance is designed to support concussion identification and management. But identification and management happen after a suspected injury or exposure has occurred [15].
Symptom recognition does not reduce the rotational forces transmitted to the brain. It does not reduce accumulated sub-concussion exposure. It does not reduce the risk from the invisible impacts that happen with no symptoms [6, 7, 8, 11].
This is the difference that Rezon has been focused on from the beginning. Brain protection must reduce the transmission of rotational forces during concussive impacts and the accumulated damage of sub-concussive impacts. That is the root cause of CTE and the triggering of neurodegenerative consequences.
Rezon Halos® is designed as brain protection, not generic head protection. Halos® reduces rotational force transmission to the brain during sub-concussion and concussion.
Why traditional head protection does not adequately address rotational force
The AFL CTE exposure should further make every sport confront the real issue: repeated rotational force transmission to the brain through accumulated sub-concussions [3, 4, 8, 11].
The future of player welfare cannot be built only around managing concussion after it happens. It must be built around reducing the rotational forces in sub-concussive impacts that make brain injury more likely in the first place.
And the responsibility of brain protection is not only with governing bodies. It is instead the choice for every parent for their child’s future brain health, for every player to decide on the value of their brain health and for every club and school to determine how important they see the risk of brain injury.
Sadly, we now know what playing without brain protection across AFL and sports looks like with too many former players globally diagnosed with CTE and other neurodegenerative diseases. This means brain protection must start earlier to reduce the transmission of rotational forces before symptoms appear, before damage accumulates, and before young athletes carry years of silent damage into adulthood.
Why Rezon Halos® Is Different
Rezon Halos® is brain protection for sport.
Its purpose is to reduce the transmission of forces associated with the biomechanics of brain injury in concussive and sub-concussive head impacts.
Rezon Halos® uses patented Rotection® technology and has been independently tested using Virginia Tech methodology.
Why Choose Halos®:
- reduces rotational force transmission by up to 61%;
- reduces linear force transmission by up to 64%;
- reduces concussion risk by 74%;
- achieved a Virginia Tech 5-Star safety rating;
- holds CE and UKCA Category II PPE certification;
- is the only non-helmeted head-worn protection to combine CE/UKCA Category II PPE certification with a Virginia Tech 5-Star safety rating [16].
This combination matters because the future of sports head protection is not only about padding the outside of the head. It is about reducing the forces transmitted to the brain.
- They didn’t know what footy was doing to their boy. ‘Now it’s too late.’ ABC News. 2026.
- Dozens of Australian Rules players diagnosed with CTE brain disease. ABC News Four Corners. 2026.
- Why Most Traumatic Brain Injuries Are Not Caused by Linear Acceleration but Skull Fractures Are. Kleiven, S. Frontiers in Bioengineering and Biotechnology. 2013.
- Head Rotational Acceleration Characteristics Influence Behavioral and Diffusion Tensor Imaging Outcomes Following Concussion. Stemper, B. D. et al. Annals of Biomedical Engineering, 2015.
- Australian Institute of Sport, Sports Medicine Australia, Australian Medical Association and Australasian College of Sport and Exercise Physicians. Concussion and Brain Health Position Statement. 2024.
- About Repeated Head Impacts. CDC. 2024.
- Neuropathologic and Clinical Findings in Young Contact Sport Athletes Exposed to Repetitive Head Impacts. McKee, A. C. et al. JAMA Neurology. 2023.
- Repeated Sub-Concussive Impacts and the Negative Effects of Contact Sports on Cognition and Brain Integrity. Ntikas, M. et al. International Journal of Environmental Research and Public Health. 2022.
- Repetitive Subconcussion Results in Disrupted Neural Activity Independent of Concussion History. Solar, K. G. et al. Brain Communications, 2024.
- Repeated Head Trauma Causes Neuron Loss and Inflammation Before Chronic Traumatic Encephalopathy. Butler, M. L. et al. Nature. 2025.
- Leveraging Football Accelerometer Data to Quantify Associations Between Repetitive Head Impacts and Chronic Traumatic Encephalopathy in Males. Daneshvar, D. H. et al. Nature Communications. 2023.
- CTE Diagnosis and Research. Australian Sports Brain Bank.
- Age at First Exposure to Repetitive Head Impacts Is Associated With Smaller Thalamic Volumes in Former Professional American Football Players. Schultz, V. et al. Journal of Neurotrauma. 2018.
- Dose-Dependent White Matter Changes Associated With Repetitive Head Impacts in Former American Football Players. Arciniega, H. et al. Brain Communications. 2026.
- Australian Concussion Guidelines for Youth and Community Sport. Australian Sports Commission. 2024.
- Brain Protection Technology. Further Reading. Rezon.
Author: Judith McMinn
