The Role of Hypoxia on Subconcussive Head Impacts
Condition: Trauma, Brain
MeSH terms: Brain Injuries, Traumatic; Hypoxia
Study type: Interventional

Summary: 
      The purpose of this study is to examine the combined effects of hypoxia and a short bout of
      subconcussive head impacts on neurocognitive and ocular-motor function and plasma expression
      of brain-derived blood biomarkers.
    

Detailed description: 
      The purpose of the pilot study is to observe preliminary trends in neural response to
      subconcussive head impacts in hypoxic condition. This work will provide a critical un-tested
      knowledge regarding the combined effects of subconcussion and hypoxic condition (mimicking
      high altitude), which will be used in our upcoming grant proposal to the Department of
      Defense (DoD). Military personnel, particularly those who are deployed to Afghanistan, are
      constantly subjected to hypoxic condition, given that the majority of military land
      operations in Afghanistan occur at 2000-3000 meters (6500-10,000 feet). This level of
      altitude does not elicit major side effects, yet neural functions may experience some degree
      of perturbation (i.e., slowed reaction time, altered night vision). Concurrently, these
      military personnel, who operate at high altitudes, often incur subconcussive forces to the
      head. These subconcussive head impacts can be induced by exposure to, for example, flash-bang
      grenades, artillery fire, recoilless rifle, improvised explosive devices (IEDs), and head
      collision. The combined effects of these two stressors have the potential to attenuate one's
      readiness, operational efficiency, and overall brain function, but the combined effects have
      never been studied to date. As a result, one of four study topics that the Defense Centers of
      Excellence deems urgent is: Document the effects of altitude exposure on mild traumatic brain
      injury (mTBI) and blast-induced neurotrauma (BINT). To answer the question, we hypothesized
      that there will be an exponential worsening in neurocognitive function and in ocular-motor
      system functioning, and increased plasma expression of brain-derived biomarkers, after
      subconcussive head impacts under hypoxic conditions.
    

Intervention name(s): Soccer heading
Intervention type(s): Behavioral
Intervention description(s): A standardized and reliable soccer heading protocol will be used to induce subconcussive impacts for the experiment. A triaxial accelerometer (Triax Technologies, Norwalk, CT) embedded in a head-band pocket and positioned back of the head to monitor linear and rotational head accelerations. A JUGS soccer machine (JUGS Sports, Tualatin, OR) will be used to simulate a soccer throw-in with a standardized ball speed of 25 mph across all groups. The ball speed is similar to when soccer players make a long throw-in from the sideline to mid-field. Soccer players frequently perform this maneuver during practices and games. Participants will stand approximately 40ft away from the machine to perform the heading. Participants will perform a total of 10 headers at a rate of 1 header per minute and will be instructed to direct the ball back towards the JUGS machine. Previous uses of this soccer heading model have reported an average peak linear acceleration per header of 14.5 to 33.5 g.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Single (Participant)
Primary purpose: Diagnostic
Keywords: soccer heading; subconcussive head impacts; hypoxia