Routine sparring can cause short term impairments in brain-muscle communication and a decrease in memory performance


Routine sparring in boxing can cause short-term impairments in brain-to-muscle communication and decreased memory performance, according to new research.

The findings emerged from a University of Stirling study that assessed boxers before and after a nine-minute sparring session – where athletes trade punches without the aim of incapacitating each other.

This study, alongside the team’s 2016 research into the impact of heading footballs, is one of the first to show that routine impact in sport – thought to be innocuous – results in measurable changes in the brain. Experts believe the findings raise further questions around the safety of other sports, where similar routine impacts occur, and say further research is required.

Dr Thomas Di Virgilio, a Lecturer in Sport, led the latest study alongside colleagues in the Stirling Brains multi-disciplinary research team.

He said: “There are still questions surrounding the relationship between repetitive routine head impacts – such as heading in football or sparring in boxing – and brain health.

The truth is that we do not currently know how much impact is safe.

“For many years, a debate has taken place around the safety of boxing, however, these discussions often focus on heavy blows inflicted during competitive fights.

In contrast, we looked at subconcussive impacts – those that are below the concussion threshold – inflicted during training sessions.

“Our findings are important because they show that routine practices may have immediate effects on the brain.

Furthermore, athletes may be at greater risk of injury if the communications between the brain and muscles are impaired.”

The team assessed the motor control and cognitive function of 20 boxers and Muay Thai (Thai boxing) athletes before and after a nine-minute sparring session (three rounds of three minutes). Measurements were taken immediately after the session, and then one-hour and 24 hours later.

Motor control was measured using transcranial magnetic stimulation – which uses magnetic fields to stimulate the nerve cells in the brains of participants – to understand how it communicates with the muscles.

The participants also completed a series of tests (the Cambridge Neuropsychological Test Automated Battery), providing objective measures of cognitive function.

The team found that, one hour after sparring, the participants showed impaired brain-to-muscle communications and decreased memory performance, relative to controls. After 24 hours, these effects returned to baseline.

Dr Di Virgilio added: “We have previously shown that the repetitive heading of footballs results in short-term changes to brain function and this latest study sought to understand whether similar effects were observed in training practices in other sports.

Although transient, we found that brain changes observed after sparring are reminiscent of effects seen following brain injury.

“Our findings are important because they show that routine practices may have immediate effects on the brain. Furthermore, athletes may be at greater risk of injury if the communications between the brain and muscles are impaired.”

“As with our previous research into heading footballs, it is not possible to say whether there is a ‘safe’ threshold when it comes to the level of impact in sparring.

Further research is required to help sportspeople – and the academic community – fully understand the dangers posed by subconcussive impacts, routine in sport, and any measures that can be taken to mitigate against these risks.”

Dr Di Virgilio worked alongside Stirling colleagues Dr Angus Hunter, Dr Magdalena Ietswaart, Professor Lindsay Wilson and Professor David Donaldson.

Dr Hunter said: “Importantly, this is a breakthrough study using pioneering techniques enabling us to understand how impaired brain to muscle signalling alters electrical recruitment patterns of leg muscle. In the short-term this may negatively affect fine motor control and thus athletic performance.”

The study was at the centre of a high-profile BBC documentary, entitled ‘Alan Shearer: Dementia, Football and Me’, presented by the former England footballer.

Chronic traumatic encephalopathy (CTE) was first described by Martland in 1928 as “punch drunk syndrome” [1], where he hypothesized that the cognitive and behavioral symptoms observed in boxing competitors were a result of sub-lethal repeated blows to the head that the fighters sustained in their careers.

It was subsequently termed “dementia pugilistica” by Millspaugh in 1937 [2]. Millspaugh noticed that the disease was characterized by memory disturbances, executive dysfunction, mood and behavioral changes, and neurological abnormalities after repetitive brain injury. Corsellis et al. [3] found that dementia pugilistica is a neuropathologically distinct condition from other neurodegenerative conditions after he presented a case series of 15 ex-boxers, which included abnormalities of the septum pellucidum associated with fenestration and forniceal atrophy, cerebellar and scarring of the brain, substantial nigral degeneration, and the occurrence of neurofibrillary tangles in the cerebral cortex and temporal horn areas.

The clinical syndrome of CTE is a combination of symptoms caused by lesions affecting the pyramidal, extrapyramidal, and cerebellar systems [4].

The cognitive and behavioral symptoms associated with CTE are reflective of the regions that have been pathologically determined to be most affected by CTE. Early cognitive symptoms primarily include learning and memory impairments. Mood changes include symptoms of depression, apathy, irritability, and suicidal thinking [5].

Behavioral issues include poor impulse control and increased aggression. Dementia would ensue in all older cases with advanced stage CTE, 10 to 20 years after retirement from the ring [6,7]. Other motor clinical signs include dysarthria in 90% of cases associated with gait ataxia. Many patients also complained of persistent headaches. Sometimes they might exhibit fine tremors, but extrapyramidal signs are rare [8].

Neuropsychological testing for former boxers suspected of having CTE has revealed difficulties in memory, information processing and speed, finger tapping speed, attention and concentration, sequencing abilities, and frontal executive functions such as planning, organization, reasoning, and judgement [6,7,9].

It has also been shown that all individuals with neuropathologically confirmed CTE cases have had repetitive head trauma [10].

Although most cases of CTE are found in people practicing martial arts, CTE has also been found in others with a history of repeated concussive injuries from sports ranging from professional hockey players [11], American football players, and military men in active line of duty, to the case of a circus clown who was repeatedly shot out of a cannon [12,13,14].

American football players with no diagnosis or history of concussions, but who played in positions subjected to the greatest exposure of repetitive trauma to the head, have also been neuropathologically confirmed to have CTE.

This suggests that repetitive sub-concussive trauma might also lead to the development of this kind of neurodegenerative disease [15].

High-profile ex-National Football League (NFL) players such as Aaron Hernandez, Junior Seau, Dave Duerson, and Andre Waters had post-mortem confirmation of CTE after rulings that their deaths were the result of suicide [16]. These suicides could possibly be related to mood and behavioral changes resulting from CTE.

In recent years, mixed martial arts (MMA) has been heavily scrutinized by a number of medical associations which have reservations about the safety of the sport due to participants receiving repeated head trauma, with some calls for the sport to be banned completely.

This is a growing concern in MMA as fighters become more aware of the risks, though there has been a paucity of mainstream reporting. In 2012, Gary Goodridge was the first MMA professional fighter to be diagnosed with CTE.

MMA is a full-contact, no holds barred mixed combat sport, combining unarmed Oriental styles of martial arts (e.g., judo, karate, muay thai, jiu-jitsu) with Western combat techniques (e.g., Greco-Roman wrestling, boxing, kickboxing) [17].

Two contestants, wearing minimal protective equipment, skillfully adopt a combination of striking and grappling techniques, both on the ground and standing, against their opponent. A contestant attains victory by concussing an opponent into a defenseless position through blunt head trauma (knockout (KO)), disabling an opponent through joint subluxation, dislocation or soft tissue trauma, causing syncope by way of a neck choke, or coercing an opponent into submission by any permutation of the preceding [18].

A technical knockout (TKO) occurs when the contestant is unable to safely defend himself, leaving himself totally defenseless.

Compared to other kinds of martial arts, MMA is a relatively new sport which started in the 1980s, and MMA competitions were first introduced in the United States (US) with the Ultimate Fighting Championship (UFC) in 1993.

It was dubbed as brutal, with no holds barred, no time limits, no weight classes, and few rules. MMA was banned for a period of time in the US during the mid-1990s after it faced heavy criticism from politicians concerned about the safety of the sport, with then-US Senator John McCain calling it “human cockfighting”.

The “Unified Rules” was introduced thereafter, which stipulates a list of prohibited acts (such as groin attacks, biting, throat attacks, head butting) to ensure the safety of participants [19].

These rules were subsequently adopted by most international MMA competitions. With the increased media attention of MMA worldwide, MMA is gaining popularity amongst the masses. MMA gyms are sprouting at an accelerated pace, with more amateurs taking on the sport. There is an urgent need for participants of this sport to be aware of the potential health hazards MMA poses to them. Additionally, there is currently no definite pharmacological treatment for CTE, though there have been animal studies suggesting the beneficial effects of anti-dementia drugs such as memantine [11].

Here, we illustrate a case of possible CTE in an MMA fighter with its chronic neuropsychiatric sequalae.

Written informed consent for the publication was obtained from the patient for this case report.

Case Presentation

In May 2010, a 40-year-old Caucasian man with adulthood-onset epilepsy came to our clinic for worsening memory and poor concentration for 1 year. He had progressive cognitive impairment, specifically short-term memory loss, word-finding difficulties, slower processing speed, and difficulties in organizing and multitasking.

There was no reported change in his mood with no signs of depression or anxiety. He was a university graduate without family history of dementia or past history of addiction. Being an avid MMA fan, he had been practicing the sport for over 10 years. He was previously in the US Marines before working as an MMA school manager and instructor for 5 years. Recurrent minor head concussions and transient asphyxiation episodes were common in his course of martial arts training and work.

On physical examination, he had hand tremors with fine motor incoordination and lower limb ataxia. Laboratory investigations, lumbar puncture, and electroencephalography revealed normal results. Magnetic resonance imaging of the brain, however, showed mild asymmetry in the parahippocampus structures with the left hippocampus appearing slightly smaller and dilatation of the left temporal horn. A neuropsychological assessment conducted in 2010 showed above-average performances on most cognitive domains except timed working memory tasks (see Table 1).

Since September 2010, he had worked as an English teacher, teaching his native language. Two years later, he could no longer stay in the job due to worsening memory and planning difficulties. He was also noted to be more irritable, with increased fatigability and distractibility. He was given methylphenidate (60 mg per day) to improve his attention. Furthermore, he developed benzodiazepine dependence but managed to undergo detoxification successfully. Repeated neuropsychological assessment in 2013 revealed worsening performance across most cognitive domains with significant decline in auditory and visual attention and memory, and further deterioration in executive function (see Table 1). The clinical and neuropsychological findings suggested chronic traumatic encephalopathy (CTE). Memantine was subsequently added to his treatment schedule and he continued to be followed up in clinic. His cognitive state deteriorated progressively and he was eventually lost to follow-up.

University of Stirling
Media Contacts:
Greg Christison – University of Stirling
Image Source:
The image is in the public domain.

Original Research: Open access
“Understanding the Consequences of Repetitive Subconcussive Head Impacts in Sport: Brain Changes and Dampened Motor Control Are Seen After Boxing Practice”. Thomas Di Virgilio et al.
Frontiers in Human Neuroscience doi:10.3389/fnhum.2019.00294


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