A brief descriptive outline of the rules of mixed martial arts and concussion in mixed martial arts

Levels of biomarkers associated with subconcussive head hits in mixed martial arts fighters

Background

Concussion and the damage resulting from this event related to brain function have been widely studied; however, little is known about subconcussive impacts, especially in Mixed Martial Arts (MMA) fighters, which is a combat and full contact sport in which most blows are aimed at the head.

Objective

This study aims to evaluate the biomarker levels associated with subconcussive hits to the head in MMA fighters.

Methods

This is an exploratory study in which 30 male subjects (10 MMA fighters, 10 healthy individuals who practice muscle training, and 10 healthy sedentary individuals) aged between 18 and 32 years (25.4 ± 3.8) were evaluated. These individuals underwent blood collection to assess their Ubiquitin C-terminal hydrolase (UCH-L1), Glial Fibrillary Acidic Protein (GFAP) and Brain Derived Neurotrophic Factor (BDNF) levels before, immediately after and 72 hours after the sparring session (for the fighters) and were compared between groups.

Results

Significant differences were found at baseline between active and healthy fighters in BDNF levels (p = 0.03). A significant reduction of BDNF levels were also observed between the post-immediate and 72h after the sparring session (p = 0.03). No differences were observed in the number or severity of symptoms reported by the fighters.

Conclusion

Despite the exploratory approach, the findings of this study may help to understand the influence of repeated subconcussive hits to the head in MMA fighters, as well as to propose preventive interventions which can minimize the effects of the impact of hits, preserving fighters' neuronal integrity and function.

Neuroimaging, wearable sensors, and blood-based biomarkers reveal hyperacute changes in the brain after sub-concussive impacts

Impacts in mixed martial arts (MMA) have been studied mainly in regard to the long-term effects of concussions. However, repetitive sub-concussive head impacts at the hyperacute phase (minutes after impact), are not understood. The head experiences rapid acceleration similar to a concussion, but without clinical symptoms. We utilize portable neuroimaging technology - transcranial Doppler (TCD) ultrasound and functional near infrared spectroscopy (fNIRS) - to estimate the extent of pre- and post-differences following contact and non-contact sparring sessions in nine MMA athletes. In addition, the extent of changes in neurofilament light (NfL) protein biomarker concentrations, and neurocognitive/balance parameters were determined following impacts. Athletes were instrumented with sensor-based mouth guards to record head kinematics. TCD and fNIRS results demonstrated significantly increased blood flow velocity (p = 0.01) as well as prefrontal (p = 0.01) and motor cortex (p = 0.04) oxygenation, only following the contact sparring sessions. This increase after contact was correlated with the cumulative angular acceleration experienced during impacts (p = 0.01). In addition, the NfL biomarker demonstrated positive correlations with angular acceleration (p = 0.03), and maximum principal and fiber strain (p = 0.01). On average athletes experienced 23.9 ± 2.9 g peak linear acceleration, 10.29 ± 1.1 rad/s peak angular velocity, and 1,502.3 ± 532.3 rad/s2 angular acceleration. Balance parameters were significantly increased following contact sparring for medial-lateral (ML) center of mass (COM) sway, and ML ankle angle (p = 0.01), illustrating worsened balance. These combined results reveal significant changes in brain hemodynamics and neurophysiological parameters that occur immediately after sub-concussive impacts and suggest that the physical impact to the head plays an important role in these changes.