Sub-concussive impacts in youth sport: what the Wake Forest study revealed about brain changes in a single season
For too long, youth sport has hidden behind a comforting fiction: if a child has not been diagnosed with concussion, the brain is fine, and the benefits of sport outweigh brain injury risk. The Wake Forest study cuts straight through that complacency. It found that in children aged 8 to 13, greater cumulative head-impact exposure over just one season was associated with measurable white matter changes, despite no diagnosed concussions [1].
That should change the conversation around brain protection in sport immediately. Because the real risk in youth sport is not confined to concussion. It is from the repeated lower-force, sub-concussive, hits that are dismissed as routine, waved away as part of the game, never noticed or tracked. This is exactly why sub-concussive impacts in youth sport deserve far more attention from parents, coaches, schools and clubs than they currently get [1].
What the Wake Forest study revealed about sub-concussive impacts in youth sport a decade ago
The Wake Forest-led paper, published in Radiology in 2016, followed youth football players over a single season and compared pre-season and post-season brain imaging. The children were between 8 and 13 years old. Helmet sensors were used to measure cumulative head-impact exposure. No player included in the final analysis had been diagnosed with concussion during that season [1].
And yet the study still found measurable brain change. Greater cumulative head-impact exposure was associated with changes in white matter tracts over that single season [1]. That matters because it punctures the lazy assumption that concussion is the only damage threshold that counts. It is not. A child does not need to stagger off a pitch, fail a sideline assessment, or receive a formal concussion diagnosis for the brain to be affected by repeated head impact exposure [1].
This is the point many parents, coaches, schools and clubs still ignore or resist. They want brain injury in sport to be obvious, visible, easy to define, manage and track. But biology is not obliged to make risk and injury convenient. The Wake Forest study did not say every sub-concussive hit causes lasting disability. It said something much more important: repeated sub-concussive exposure can produce measurable brain change in the developing brain before sport ever calls it concussion [1].
Can lower-force impacts affect the brain even without concussion?
This is where the conversation has to get more honest. Parents, coaches, clubs and schools are often taught to watch for concussion symptoms. They should, but symptom watching is not brain protection. It is a response after the event, and after brain damage has been inflicted. Concussion protocols do nothing to address the repeated sub-concussive impacts that never trigger concussion signs in the first place [1].
The broader brain-injury literature points in the same direction. A 2015 review of neuropathologically confirmed chronic traumatic encephalopathy (CTE) cases reported that 1 in 5 athletes with CTE had no documented history of concussion [2]. Boston University later summarised related work, stating that approximately 20 percent of athletes with CTE had never suffered a diagnosed concussion [3]. That does not mean the children who participated in the Wake Forest study are destined for the same outcome. It does, however, make one thing very clear: a recorded concussion is not the full measure of brain injury risk [2, 3].
That is precisely why the Wake Forest study matters to parents and why action is needed a decade after its release. It reinforces a principle sport has been very slow to accept: lower-force, sub-concussive impacts are not harmless simply because they do not announce themselves. When those impacts are repeated, and particularly when the brain receiving them is still developing, pretending concussion is the only concern becomes untenable [1].
Watch: You don’t need a concussion to suffer brain injury in sport.
Why are ages 8 to 12 so important for brain development?
The age of the children in the Wake Forest study is not a footnote. It is the reason the findings are so important. These were not adult brains. They were not the brains of professional athletes. These were developing brains in late childhood and early adolescence; a period of major structural and functional change [1, 4].
Research on adolescent neurodevelopment shows that this stage involves ongoing maturation of white matter and major regional changes in grey matter. One widely cited review notes that frontal cortex grey matter volume peaks at around 11 years in girls and 12 years in boys, while white matter continues to mature across adolescence [4]. In other words, the age range examined in the Wake Forest study sits squarely inside a critical developmental window [1, 4].
That matters because a developing brain is not simply a smaller adult brain. It is still building, still refining, still organising the neural architecture that supports memory, attention, emotional regulation, judgement, and learning over time [4]. So when repeated head impacts occur during this stage, the answer cannot be reassurance built on instinct. It has to be caution built on evidence [1, 4].
Too often, youth sport leans on soft phrases such as “kids are resilient” or “children bounce back.” Those lines are not science. They are cultural habits. And they are dangerous when they are used to justify inaction and non-use of brain protection [4].
Why do parents underestimate brain injury risk in youth sport?
This blind spot is not theoretical. Rezon’s recent survey data shows that many adults underestimate brain-injury risk in children. Conducted in partnership with the UK National Innovation Centre for Ageing and Voice®, the survey found that 57 percent of participants mistakenly believed children are at lower risk of brain injury in sport than adults [5, 6].
That belief should concern every parent. Because once adults assume youth sport is automatically less dangerous, they stop asking questions about brain protection. They become less alert to repeated head impacts. They tolerate more exposure in training. They focus on visible injury and ignore cumulative sub-concussive loading and damage to the brain. They treat the absence of concussion as evidence of brain safety [1, 5, 6].
The Wake Forest study directly challenges that false confidence. It flags that risk in youth sport starts much earlier than many parents think, sits lower down the exposure scale and well before a professional career than many governing bodies have been willing to admit [1]. This is not an argument against sport. It is an argument against brain protection complacency.
How can parents protect a child’s brain in sport?
Parents should start with the most important principle: the best way to reduce brain-injury risk is to reduce the force transmitted to the brain in the first place; especially rotational force transmission [7]. Rotational forces cause the brain to rotate inside the skull. 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. Rotational forces are widely recognised as a primary biomechanical driver of concussion and broader brain injury mechanisms [7].
This is where conventional sports headgear falls short. Traditional head protection has largely been designed to protect the scalp, ears, and surface of the head from cuts, abrasions, and blunt contact. That is not the same as protecting the brain [6, 7]. If parents are serious about reducing risk, they need to think beyond whether a product looks protective and determine whether it is designed to address the rotational forces most associated with brain injury [7].
Rezon Halos® has been designed as brain protection, rather than generic head protection. Halos® is designed specifically to reduce rotational force transmission during concussive and sub-concussive impacts. Halos® reduces rotational force transmission by up to 61%, reduces concussion risk by 74%, and is the only non-helmeted head-worn protection to hold both CE / UKCA Category II PPE certification and a Virginia Tech 5-Star safety rating [6, 8, 9].
No sports headguard removes all risk from sports. But reducing rotational force transmission is a more effective protection strategy than relying on concussion recognition after damage has already occurred [7, 8]. In light of the Wake Forest report, parents should demand a reduction in avoidable contact in training, seek a better understanding of cumulative exposure, and demand the use of brain protection designed around the biomechanics of brain injury [1, 7, 8].
“I have coached rugby for over 30 years and witnessed the consequences of repeated head injury. Rezon stands out as a pioneer of protection against rotational force damage.”
⭐⭐⭐⭐⭐ Steven Colwell | Rugby Coach
Why does the Wake Forest study matter for parents?
The Wake Forest study matters because, a decade ago, it exposed a dangerous gap between what adults look for and what the brain may actually experience. A child can complete a season without a diagnosed concussion and still show measurable brain changes associated with repeated sub-concussive head impacts [1].
Parents do not need more comforting myths about the benefits of youth sport. They need a clearer standard for brain safety.
Repeated lower-force sub-concussive impacts matter. Ages 8 to 12 are a critical developmental window, but brain development continues into the 20s, and repeated head impacts pose a risk across the sporting lifespan. Symptom-based concussion protocols are necessary, but they are not enough. Better recognition and recording of concussion does not reduce the sub-concussive damage that can accumulate long before a diagnosis is made.
The most credible brain protection strategy is to reduce rotational force transmission before injury is inflicted and reduce the cumulative exposure wherever possible [1, 4, 7].
That is the real lesson from Wake Forest. Not panic. Not sensationalism. Just a hard scientific truth that youth sport and those involved in youth sport can no longer afford to ignore.
- 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.
- Epidemiology of mild traumatic brain injury and neurodegenerative disease. Gardner RC, Yaffe K. Molecular and Cellular Neuroscience. 2015. PubMed
- Study: Hits, Not Concussions, Cause CTE. Boston University School of Medicine. 2018.
- Adolescent Maturity and the Brain: The Promise and Pitfalls of Neuroscience Research in Adolescent Health Policy. Johnson SB, Blum RW, Giedd JN. Journal of Adolescent Health. 2009.
- What are sub-concussions and how do they impact long-term brain health? Further Reading. Rezon.
- Rezon Survey 2025. Further Reading.
- How Does Rotational Force Cause Brain Injury in Sport and How Can It Be Reduced? Further Reading. Rezon.
- Brain protection technology for sport | Reducing rotational force. Further Reading. Rezon.
- Rezon Halo® Brain Protection in Sport.
Author: Judith McMinn
