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Introduction

The introduction of the UK-wide Concussion Guidelines for Grassroots Sport in April 2023 marked a significant step forward in ensuring athlete safety by providing clear protocols for identifying, managing, and preventing concussions. This initiative prioritises removing participants from play if there is any doubt of injury, focusing on immediate care and gradual recovery to minimise long-term risks. All kickboxing officials, promoters, coaches, athletes, and legal guardians of minors should familiarise themselves with these guidelines and promote awareness within their clubs and events. Additional information is available on the Kickboxing GB Education Hub under “Concussion Guidelines.”

Concussion Guidelines

While these guidelines focus on acute concussions, growing concerns about the cumulative effects of subconcussive impacts — repeated, low-level brain traumas without immediate symptoms — are emerging as a critical issue.


Understanding Sub-Concussive Impacts

A sub-concussive impact occurs when a force is transmitted to the brain but does not reach the clinical threshold for a concussion. These impacts are common in combat sports, where repeated strikes to the head—even if not powerful enough to cause immediate symptoms—can still affect brain function. Scientific evidence shows that even low-force impacts can have long-term consequences, particularly for children. Below are some key findings:

  1. Cumulative Brain Damage:
    • Repeated subconcussive impacts—low-force hits that don’t cause immediate symptoms—can result in structural and functional changes in the brain. These changes include alterations in brain anatomy and impaired cognitive function, even in the absence of a diagnosed concussion. Researchers reviewed 24 previous studies that tracked athletes over time, focusing on those that measured both the physical forces involved in these minor head impacts and their effects on the brain. (Deutsche Sporthochschule Köln).

      Conclusion: The study concluded that while repeated minor head impacts can lead to changes in brain structure, more research is needed to fully understand how these structural changes impact brain function and overall health. In simple terms, the research suggests that even if individual head impacts don’t cause immediate symptoms, their cumulative effect over time can alter the brain’s structure. However, it’s still unclear how these structural changes affect how the brain works day-to-day.
  1. Disruption of Neural Signaling:
    • Subconcussive hits can interfere with GABA signaling pathways in the brain. GABA (gamma-aminobutyric acid) is like your brain’s “chill-out” chemical. It helps calm things down when your brain gets too excited or overstimulated. Think of it as the brakes on a car—without it, your brain might go into overdrive, causing stress, anxiety, or trouble controlling your movements. Here’s an easy way to think about it: When things are too hectic: GABA steps in and says, “Relax, slow down,” helping your brain stay balanced and focused. If GABA isn’t working right: Your brain might feel overstimulated, like too much noise or chaos, which can lead to problems with coordination, memory, or mood. So, GABA is the brain’s natural way of keeping things under control and running smoothly!
    • This disruption can lead to motor control and memory impairments, impacting coordination and cognitive functions. (Frontiers in Human Neuroscience). This study looked at 20 amateur boxers after routine sparring alongside a control group of 20 boxers who participated in mock sparring with no contact to the head.
Sparring was 3x3min rounds, and the assessment was made before, immediately after, one hour after and 24 hours after the sparring session. Outcome:
      • Increased Corticomotor Inhibition: One hour after sparring, boxers exhibited a significant increase in corticomotor inhibition compared to controls, indicating heightened GABAergic activity.
      • Altered Motor Control: Changes in motor unit recruitment strategies were observed, suggesting impairments in motor control post-sparring.
      • Memory Performance: Boxers showed decreased memory performance one hour after sparring relative to controls.
      • Recovery: By 24 hours post-sparring, most measures returned to baseline levels, indicating that the observed changes were transient.
  1. Effects on Developing Brains:
    • Children’s brains, which are still developing, are particularly vulnerable to these impacts. Subconcussive hits during critical growth phases can impair cognitive, emotional, and motor development, with potential long-term consequences like memory issues, mood disorders, and neurodegenerative conditions later in life.
    • The (American Brain Foundation). study focuses on how repeated minor head impacts, especially during childhood, can affect brain development. These impacts, called subconcussive hits, don’t cause immediate symptoms but can still harm the brain over time. Key Points:
      • Vulnerable Developing Brains: Children’s brains are still growing and are more sensitive to damage. Hits during this time can disrupt normal brain development.
      • Cumulative Damage: Even small, repeated impacts can weaken the brain’s defenses, like the blood-brain barrier, leading to long-term issues.
      • Potential Effects: Over time, these hits can result in problems with memory, emotions, motor skills, and even increase the risk of neurological conditions like depression or dementia.


Takeaway & Specific Risks to Children

The human brain continues developing into the mid-20s, with the prefrontal cortex — responsible for decision-making and impulse control — maturing last. Disruptions during this period can cause permanent impairments. Even if children don’t show signs of injury after small head impacts, these hits can quietly add up and harm brain development. This is why reducing exposure to head impacts, especially for children, is so important. The American Brain Foundation’s conclusions on the effects of repetitive subconcussive impacts are supported by several key pieces of evidence:

  • Breakdown of the Blood-Brain Barrier:
    • Repetitive subconcussive hits can compromise the blood-brain barrier, a protective shield that prevents harmful substances from entering the brain. This breakdown can lead to various neurological issues. American Brain Foundation
  • Cumulative Brain Damage:
    • Studies indicate that even in the absence of immediate symptoms, repeated minor head impacts can cause cumulative damage to the brain, potentially leading to long-term cognitive and neurological impairments. American Brain Foundation
  • Increased Risk of Chronic Traumatic Encephalopathy (CTE):
    • Research has linked repetitive subconcussive head impacts to the development of CTE, a progressive neurodegenerative disease characterised by symptoms such as memory loss, mood disorders, and cognitive decline. AAFP

These findings underscore the importance of minimising repetitive head impacts, especially in children and adolescents, to protect long-term brain health. On the UK domestic competition scene, children as young as 9 often compete in multiple bouts per event, sometimes every other weekend. In continuous divisions these bouts frequently involve toe-to-toe exchanges with limited defensive skills, particularly in novice and younger age groups. Starting competition early increases the number of head impacts over time. The long-term effects of such exposure may not be evident for decades but could include:

  • Memory loss
  • Impaired judgment
  • Mood disorders
  • Neurodegenerative conditions like Chronic Traumatic Encephalopathy (CTE).


The Danger in Kickboxing’s Light-Contact Disciplines

Subconcussive impacts in light-contact sparring are a particular concern.  Unlike Ringsports, the perception is that  there is less danger, and this typically means a less regulated approach in terms of medical checks & weight control.  However experience and a recent review of online footage shows that the number of hits to the head in light contact disciplines is much greater than in full contact. This number goes up exponentially as the level of experience reduces i.e. fighters in novice divisions get hit the most.

The evidence presented above tells us that repeated low-force blows to the head can accumulate, disrupting brain tissue and increasing the risk of long-term damage. The stop-start nature of point fighting provides a safer environment for skill development, whereas continuous sparring exposes novices and younger age groups to unnecessary risk due to their limited defensive skills.

While combat sports inherently involve head contact, steps can be taken to minimise the risks associated with sub-concussive impacts and coaches and parents are urged to consider the following recommendations:

1. Emphasize Technique and Defensive Training and delay competitive sparring

    • Emphasize defensive skills such as head movement, blocking, and footwork to reduce direct head contact.
    • Train athletes to recognise when they are overexposed to head impacts and encourage strategic engagement over brute force.
    • Introduce competitive sparring in divisions such as Light Contact and Kick Light only when athletes demonstrate advanced skills in distance control and evasion, i.e. don’t enter them in novice or even intermediate divisions because, by definition, they don’t have the skills necessary to reduce head trauma.

2. Equipment and Protective Measures

    • Use high-quality, well-fitted headgear in sparring to absorb some impact forces (though headgear does not prevent all damage).
    • Ensure mouthguards are properly fitted, as they may help in reducing jaw-related trauma that can transmit force to the brain.
    • Wear larger gloves in training to spread the force of impact, e.g. Under 57kg – 12-14oz; 57-69kg – 14oz; 69-84kg – 16oz; Over 84kg – 16-18oz

3. Promote Safer Training Practices

    • Limit the frequency and intensity of sparring sessions to reduce cumulative head trauma, allow at least 24 hours of recovery between sessions.
    • Avoid sparring for 24-48 hours after competitions, in line with the “If in doubt, sit them out” protocol.
    • Incorporate more technical drills and controlled sparring over heavy contact sessions.
    • Encourage clean sparring with mandatory breaks (e.g. step back after every three strikes).
    • Use alternative training methods such as shadowboxing, partner drills, and bag work to improve skills without excessive head contact.
    • Take an age and skilled based progressive approach to the introduction of head contact e.g. body contact only in the early novice stage, as skill develops introduce headshots with punches only, then at advanced levels introduce head kicks.

4. Stricter competition protocols

    • Consider enforced stoppages after headshots which result in an 8-count. This would require athletes to rest for 24-48 hours before resuming activity and is in line with the current Government concussion protocols for all UK grassroots sports.

5. Educate your community

    • Clubs should raise awareness among its referees, coaches, and parents about the risks of sub-concussive impacts and the importance of reducing cumulative exposure.


 

Risks of Ignoring the Evidence

The risks of sub-concussive impacts in kickboxing cannot be ignored. The cumulative effect of repeated blows, even in light-contact disciplines, poses serious long-term risks to athletes’ neurological health.

  1. Chronic Traumatic Encephalopathy (CTE):
    • Linked to repeated head trauma, even at low levels. Symptoms may include memory loss, depression, and progressive cognitive decline.
  2. Structural Brain Changes:
    • Sub-concussive impacts can cause white matter damage and brain shrinkage over time, affecting memory and decision-making.
  3. Cognitive Decline:
    • Increased risk of early-onset Alzheimer’s and other dementias.
  4. Second Impact Syndrome (SIS):
    • A rare but catastrophic condition where a second injury occurs before full recovery from a previous trauma which in a worse-case scenario can result in the death of the athlete.
  5. Mental Health Issues:
    • Links to mood disorders such as depression and aggression, even without visible neurological damage.

Conclusion

Sub-concussive impacts pose a hidden but serious risk to athletes in contact sports. While they may not cause immediate symptoms, their cumulative effects can lead to long-term neurological damage, including CTE and cognitive decline. By implementing proper training techniques, using protective equipment, modifying training intensity, and conducting regular medical assessments, the risks associated with sub-concussive impacts can be significantly reduced. Increased awareness and proactive changes in training practises can help safeguard the health and longevity of athletes.

Kickboxing GB recommends that all clubs…

  • Review current practices and conduct risk assessments.
  • Take steps to reduce head impacts in training and competition.
  • Ensure the safety and long-term health of athletes remains the highest priority.

By addressing these issues proactively, we can ensure kickboxing remains a safe and enjoyable sport for all participants, particularly children.