Does Ball Heading Affect More Than the Brain in Footballers?

In the world of sports, soccer is unique because of the purposeful use of the unprotected head for controlling and advancing the ball. This skill obviously places the player at risk of head injury and the game does carry some risk. Head injury can be a result of contact of the head with another head (or other body parts), ground, goal post, other unknown objects, or even the ball. Such impacts can lead to contusions, fractures, eye injuries, concussions or even, in rare cases, death. Coaches, players, parents and physicians are rightly concerned about the risk of head injury in soccer.

Current research shows that selected soccer players have some degree of cognitive dysfunction. It is important to determine the reasons behind such deficits. Purposeful heading has been blamed, but a closer look at the studies that focus on heading has revealed methodological concerns that question the validity of blaming purposeful heading of the ball. In this article we will look at the some of the key factors involved in the potentially underrecognized importance of sub concussive impacts in soccer, as well as their implications for motor-impairments and associated injury risks.

Mild Traumatic Brain Injury (mTBI) and Ball Heading

While it is likely that the sub concussive impact of purposeful heading is a doubtful factor in the noted deficits, it is unknown whether multiple sub concussive impacts might have some lingering effects. In addition, it is unknown whether the noted deficits have any affect on daily life.

Soccer accounts for a major number of sub-concussive episodes in sports: excessive heading of the ball (more than 1000 episodes per year) may cause subclinical brain injury, the effects of which are not as well defined as those of recognized for concussions generally. Although most published studies have focused on collegiate and professional players, most soccer players are amateur recreational league players.

Heading with the unprotected head to direct the ball during game play is increasingly recognized as a major source of exposure to concussive and sub-concussive repetitive head impacts. These impacts have been linked to changes in brain structure visible on neuroimaging, and decreased performance on cognitive tasks both with short term and long-term exposure.

Concussion involves several clinical domains: symptoms, physical signs, behavioral changes, cognitive impairment, and sleep disturbance. The physical signs of concussion can resolve quickly, but some players may manifest persistent impairments.

UEFA first published a call for research proposals in May 2017, in which potential researchers were asked to address two key topics.

• Determining the burden of heading in youth football; addressing differences in the way headers are taught in football training.

• Assessing differences in the incidence and characteristics of football headers in matches and training, and in different age and gender categories.

Sub-Concussion Effects in the Neuromuscular Control of the Knee

The ACL ruptures when the stresses to which it is exposed exceed its mechanical properties. However extreme knee loading scenarios may be potentiated through abnormal neuromuscular control in the lower limb, with gender differences in hip rotation and rear foot pronation in the transverse and frontal planes.

Concussion can also result in decreased postural stability from impairment on the afferent signals from the cervical spine, the vestibular-ocular system, and the visual systems. Persistent sensorimotor impairment after resolution of concussion symptoms would likely contribute to an increased injury risk, and further studies are warranted. These neurocognitive impairments are likely highly inter-twined with neuromuscular control, motor learning, and other aspects critical for the performance and safety of the athlete.

From a sports traumatology and rehabilitation perspective, we should try and produce intervention models first, which allow assessment of neurocognitive performance and identify athletes at risk for injury. Also, in the rehabilitation process, neuromuscular training tools should incorporate progressively more challenging tasks.

The benefits of using tasks such as dual-attention during clinical assessment are currently being explored when assessing and managing concussion. This strategy can be successfully translated to ACL injury risk screening, and neurocognitive strategies may be employed in ACL injury prevention and ACL injury rehabilitation. Sports activities demand initiating and maintaining appropriate performance of dynamic activities in a complex, rapidly changing environment. The success of each action is contingent on voluntary and in-voluntary motor commands modulated by sensory processing, attention, and motor planning.

Baseline Symptoms Matter

The assessment of concussion symptoms is a cornerstone to assessing individuals with this injury (P. McCrory et al., 2013). However, concussion symptoms are typically assessed only at post injury time intervals. In other words, clinicians usually do not know a patient’s pre injury or baseline level of symptoms.

Researchers have reported that baseline levels of concussion-related symptoms among healthy individuals vary considerably, with some individuals reporting no symptoms at baseline and others reporting high levels (Iverson & Lange, 2003). Several explanations have been posited for this variability in symptoms among healthy individuals, including the overlap between concussion-related symptoms and symptoms from other health conditions, including fatigue, orthopedic injuries, and physical illness (Piland, Ferrara, Macciocchi, Broglio, & Gould, 2010). Many different health conditions share symptoms such as headache, fatigue, dizziness, and sleeping problems, all of which are common following a concussion.”

NeuroTracker is one example of an excellent tool for baseline assessments of the neurocognitive sta-tus of an athlete. These types of neurotechnologies could provide a valuable rehab tool for monitoring concussion symptomatology and more subtle long-term consequences of head injuries.

Takeaways

Neuroscience will continue to help uncover how the brain and central nervous system influences and determines motor control, and the mechanistic errors in motor control resulting in non-contact lower limb injuries. Poor baseline neurocognitive performance or impairments in neuro-cognitive performance via sleep deprivation, psychological stress, or concussion injury can increase the risk for subsequent musculoskeletal injury. Head injury prevention programs span well beyond ACL injury, and their impact will extend to prevention of impairment of neural function and neurocognition.

If you’re interesting in exploring this topic further, you can read my recently published open-access paper here.

Ball heading and subclinical concussion in soccer as a risk factor for anterior cruciate ligament injury

Kakavas, G., Malliaropoulos, N., Blach, W. et al. Journal of Orthopaedic Surgery and Research, Res 16, 566 (2021).

Or if you would like to learn more about the importance of cognitive dimension in sports performance, here is an earlier Experts Corner blog that I wrote.

3 Reasons Why the Brain Rules Everything in Sports

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