Are women at higher risk of brain injury in sport?
Yes. Women are more susceptible to sport-related concussion and often experience longer recovery than male athletes. This is linked to a combination of biomechanics, neck strength, hormonal factors, sport design, reporting behaviour and historic underrepresentation in concussion research. The most direct way to reduce risk is to reduce the rotational forces transmitted to the brain during concussive and sub-concussive head impacts.
Why women’s brain injury risk needs its own conversation
Women are not smaller men.
Sport has often treated the male athlete as the default. Training systems, rules, equipment, safety assumptions, and much of the concussion evidence base have historically been shaped around male bodies, male participation, and male brain injury data.
A British Journal of Sports Medicine review found that studies informing three influential concussion consensus and position statements were 80.1% male. The same review found that 40.4% of the cited studies included no female participants at all [1].
This does not mean existing concussion protocols are unhelpful. It means they should not be treated as the whole answer for women’s sport.
If the evidence base is mostly male, it cannot automatically be assumed to explain how female athletes experience brain injury, symptoms or recovery.
Why rotational forces matter in women’s sport
Rotational forces are an important factor in concussion and sub-concussive brain injury in head impacts.
The brain sits inside the skull, surrounded by fluid. When the head accelerates or rotates rapidly as in a head impact, the brain can move and deform. Rotational acceleration is especially important because it can create shear strain across brain tissue, disrupt neural networks, affect small blood vessels and contribute to neuro-inflammatory processes.
This matters in women’s sport because many common sporting impacts involve rotation: a tackle, a fall, a collision, a heading duel in football, a ball strike or head-to-ground contact.
Female athletes may also experience different impact patterns from male athletes. In some sports, women are more likely to sustain concussion through ball, equipment or surface contact, while men are more often injured through direct player-to-player collision [4, 5]. That distinction matters because unexpected impacts give the athlete less time to brace the neck, prepare the body or control head movement before contact [6].
When the head is not stabilised before impact, rotational acceleration can increase. The neck cannot act as effectively as a dynamic shock absorber, and more rotational force may be transmitted through the skull to the brain. This helps explain why the same apparent impact can produce different consequences in different athletes.
This is not a question of female athletes being fragile. It is physics interacting with anatomy, timing and impact direction.
Female athletes may also experience different head and neck biomechanics. The systematic review of female sport-related concussion reported that female athletes appear to sustain more severe concussions than male athletes, in part because of lower biomechanical threshold tolerance for head impacts [2].
What happens inside the brain during a head impact?
Biomechanics explains how force reaches the brain. Structural neuroscience helps explain why those forces may affect athletes differently.
During a rapid head impact, rotational acceleration creates shear strain across brain tissue. This strain disrupts white-matter pathways, tears axons, affects small blood vessels, alters neural signalling and triggers inflammatory processes [7, 8].
Emerging neuroimaging and preclinical research suggests that biological sex may influence how brain tissue responds to mechanical loading. Differences in white-matter organisation, connectivity patterns and regional vulnerability may affect how forces propagate through neural tissue [9, 10]. In practical terms, the same event that produces no symptoms in one athlete may create greater neurological disruption in another.
This is one reason female-specific concussion research matters. If the underlying tissue response, symptom profile and recovery trajectory are not identical, then assessment, prevention and protection strategies should not simply be copied from male-derived data.
Hormonal factors: what the evidence actually says
Hormones should not be used as a vague explanation for women’s concussion risk. But they also should not be ignored.
Female concussion research increasingly suggests that menstrual-cycle phase, progesterone levels and hormonal contraceptive status may influence symptom burden and recovery.
A 2024 study of adolescent female athletes aged 14–18 found that self-reported symptom scores were higher among concussed females in the luteal phase, when progesterone levels are highest. The authors concluded that progesterone levels may contribute to heightened symptom experience during the acute phase of sport-related concussion [11].
A separate preliminary study of female club athletes after mild traumatic brain injury found a significant relationship between progesterone, cerebral blood flow and perceived stress symptoms. The authors reported that cerebral blood flow mediated the relationship between progesterone and perceived stress symptoms, suggesting that sex hormones may be relevant to post-concussion neurophysiology and symptom reporting [12].
A systematic review also reported that concussion may alter the hypothalamic-pituitary-ovarian axis and may be associated with worse symptoms and amenorrhea in female athletes [2].
The careful conclusion is this:
Hormones are not the single cause of women’s increased concussion susceptibility. But menstrual-cycle biology, progesterone and hormonal status appear to be relevant variables that have historically been under-measured in concussion research.
For women’s sport, that is a serious evidence gap.
Women often play sports designed around men
Many sports were codified, professionalised and equipped around male participation before women’s sport received comparable investment, research or visibility. That matters.
The question is not whether women need a lesser version of sport. The question is whether rules, equipment and safety systems have been tested against female-specific biomechanics and injury data.
In football and rugby, the ongoing ball-size debate is part of this wider issue. Should equipment standardised around male athletes automatically be assumed to be optimal for women? The same question can be asked about heading exposure, collision loads, pitch dimensions, tackle technique, training intensity and protective equipment across women’s sport.
The same principle applies to impact exposure. A head impact from a ball, tackle, fall or collision does not affect every athlete in the same way. Head size, neck strength, anticipatory control, playing style, field position, rules, coaching practice and equipment assumptions all influence the forces that reach the brain.
This is why women’s sport needs more than equal access to existing systems. It needs safety systems tested against female-specific biomechanics and injury data.
Why concussion protocols are not enough for women’s sport
Concussion protocols are essential. They help athletes, coaches, clinicians and parents recognise suspected concussion, remove athletes from play, and guide return-to-sport decisions.
But a concussion protocol is not the same as brain protection.
It is a response system.
The Canadian Guideline on Concussion in Sport covers areas such as education, recognition, onsite assessment, medical assessment, concussion management, interdisciplinary care and return to sport [16]. These are important steps, but they operate around suspected or diagnosed concussion.
For women’s sport, this distinction is especially important because female athletes may experience concussion risk, symptoms and recovery differently from male-derived assumptions.
Concussion protocols help answer: What should happen after suspected injury?
Brain protection asks: How can we reduce the forces reaching the brain in the first place?
For women’s sport, the priority should be clear: protocols remain essential, but they should be supported by protection strategies that reduce the forces transmitted to the brain before symptoms appear [2, 3, 13, 18].
“Rezon Halos® reduces the cumulative dose of sub-concussive impacts to the brain in contact sports. Sub-concussive impacts are the primary cause of Chronic Traumatic Encephalopathy (CTE), today’s most feared complication of rugby, football and other contact sports.”
Dr Emer MacSweeney, Consultant Neuroradiologist and co-founder of Re:Cognition Health, is part of Rezon’s expert team.
Taken together, the evidence suggests that women’s brain injury risk is not explained by reporting behaviour alone. Female athletes may present with different injury mechanisms, different biomechanical thresholds, different symptom patterns, hormonal variables that are still undermeasured, and structural factors that may influence how rotational forces affect the brain.
The conclusion is not that women’s sport is inherently unsafe. The conclusion is that women’s sport deserves brain protection strategies built around female-specific evidence.
The best mitigation is to reduce rotational force transmission to the brain
The central issue in women’s sport is not only whether concussion is recognised after it happens.
It is whether enough is being done to reduce the forces that reach the brain in the first place.
Protocols are essential, but they are reactive. Conventional head protection may reduce superficial injury, but it was not designed to protect the brain. The most direct mitigation is to reduce rotational force transmission during concussive and sub-concussive impacts. That is the purpose of Rezon Halos®.
Rezon Halos® uses patented Rotection® technology and is designed to reduce rotational force transmission to the brain. Halos® reduces rotational force transmission by up to 61% in head-to-head impacts, carries a Virginia Tech 5-Star safety rating, and showed a 74% reduction in concussion risk using Virginia Tech methodology. Halos® is the first and only CE/UKCA Category II PPE-certified protective headband [19].
For women’s sport, this distinction matters. Brain protection cannot rely only on recognising concussion after injury. It must also reduce the mechanical forces that contribute to injury risk.
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- Under-representation of female athletes in research informing influential concussion consensus and position statements: an evidence review and synthesis. D’Lauro C, Jones ER, Swope LM, Anderson MN, Broglio SP, Schmidt JD. British Journal of Sports Medicine.
- Sport-Related Concussion in Female Athletes: A Systematic Review. McGroarty NK, Brown SM, Mulcahey MK. Orthopaedic Journal of Sports Medicine. 2020.
- Are Sex Differences in Collegiate and High School Sports-Related Concussion Reflected in the Guidelines? A Scoping Review. Musko PA, Demetriades AK. Brain Sciences. 2023.
- Women Are at Higher Risk for Concussions Due to Ball or Equipment Contact in Soccer and Lacrosse. Ling DI, Cheng J, Santiago K, et al. Clinical Orthopaedics and Related Research. 2020.
- Sex-based differences in concussion incidence and its underlying injury mechanism in team bat/stick sports: a systematic review and meta-analysis. Sundaram V, Ramachandran AK, Singh U, Pearce AJ. International Journal of Sports Science & Coaching. 2023.
- Effect of neck muscle strength and anticipatory cervical muscle activation on the kinematic response of the head to impulsive loads. Eckner JT, Oh YK, Joshi MS, Richardson JK, Ashton-Miller JA. American Journal of Sports Medicine. 2014.
- Why Most Traumatic Brain Injuries Are Not Caused by Linear Acceleration but Skull Fractures Are. Kleiven S. Frontiers in Bioengineering and Biotechnology. 2013.
- Mechanisms of Local Stress Amplification in Axons near the Gray-White Matter Interface. Alisafaei F, Gong Z, Johnson VE, Dollé JP, Smith DH, Shenoy VB. Biophysical Journal. 2020.
- Sex-Related Differences in the Effects of Sports-Related Concussion: A Review. Koerte IK, Schultz V, Sydnor VJ, et al. Journal of Neuroimaging. 2020.
- Using Neuroimaging to Identify Sex Differences in Adults with Sports-Related Concussion: A Systematic Review. MacLeod H, et al. Brain Imaging and Behavior. 2025.
- Progesterone / menstrual-cycle phase study in adolescent female athletes after sport-related concussion. Ott S, Redell J, Cheema S, Schatz P, Becker E. Developmental Neuropsychology. 2024.
- Preliminary Report: Cerebral blood flow mediates the relationship between progesterone and perceived stress symptoms among female club athletes after mild traumatic brain injury. Chen Y, Herrold AA, Gallagher V, et al.
- Clinical Recovery Timelines After Sport-Related Concussion in Men’s and Women’s Collegiate Sports. Bretzin AC, Esopenko C, D’Alonzo BA, Wiebe DJ. Journal of Athletic Training.
- First-Time Sports-Related Concussion Recovery: The Role of Sex, Age, and Sport. Neidecker JM, Gealt DB, Luksch JR, Weaver MD. Journal of the American Osteopathic Association.
- Age and sex differences in symptom burden and clinical recovery following sport-related concussion. McGuinty D, Ballinger K, Girardin R, Ellis M, Russell K. Paediatrics & Child Health.
- Canadian Guideline on Concussion in Sport. Parachute Canada.
- What does sport governing body approval mean? Further Reading. Rezon.
- Rezon’s Expert Team.
- Product Testing. Further Reading. Rezon.
