Hyper-acute effects of sub-concussive soccer headers on brain function and hemodynamics

Area of Science:

• Sports Medicine
• Neuroscience
• Biomechanics

Background:

• Sub-concussive head impacts from soccer headers are frequent, with thousands occurring per season.
• The acute and long-term effects of these impacts, similar to concussion accelerations but without clinical symptoms, are not fully understood.
• Understanding the immediate physiological response to repetitive sub-concussive impacts is crucial for player safety.

Purpose of the Study:

• To investigate the immediate functional outcomes of sub-concussive head impacts experienced during soccer heading in a natural environment.
• To assess hyper-acute changes in brain hemodynamics and neurocognitive function following repetitive heading actions.

Main Methods:

• Twenty university soccer players were instrumented with sensors to record head impact kinematics.
• Functional near-infrared spectroscopy (fNIRS) and transcranial Doppler (TCD) ultrasound measured brain oxygenation and blood flow velocity.
• Upper extremity dual-task (UEF) neurocognitive testing was performed pre- and post-heading exposure.

Main Results:

• Athletes experienced average peak linear acceleration of 30.7 g and peak angular velocity of 7.2 rad/s.
• fNIRS revealed increased brain oxygenation in the left prefrontal cortex and left motor cortex post-heading (p < 0.01).
• Increased signal entropy in fNIRS data was observed in multiple brain regions, indicating altered brain activity.

Conclusions:

• Repetitive soccer headers induce immediate, measurable hemodynamic changes in brain oxygenation.
• No significant changes in balance or neurocognitive function were detected, suggesting mild impact levels.
• This study pioneers the use of non-invasive, portable imaging for real-time monitoring of sub-concussive head impacts, offering a framework for future research and safety protocols.