Effects of Soccer Heading on Ocular-motor Function and Blood Biomarker
Condition: Trauma, Head
MeSH terms: Craniocerebral Trauma
Study type: Interventional

Summary: 
      Repetitive head impacts in sports and military may cause deleterious effects in the nervous
      system. Investigators' previous works in football players have shown promising results in
      prediction of concussion and prevention of long-term defect using eye-movement paradigm
      (ocular-motor system) and blood biomarker. However, acute head impact effects on
      aforementioned parameters remain unknown. Thus, to answer a critical research question that
      whether or not ocular-motor system and brain-derived blood biomarker may be acutely altered
      following 10 successions of controlled soccer heading. To answer the question, investigators
      hypothesized that acute bout of soccer heading will not elicit noticeable change in subject's
      symptoms but to induce a transient defect in the ocular-motor system and increase plasma
      expression of brain-derived biomarker.
    

Detailed description: 
      Adult aged soccer players aged 18-26 years will be recruited via listserv email to Indiana
      University undergraduate students. Once subjects fulfill inclusion criteria and free of
      exclusion criteria, participants will be randomly assigned to one of two groups (Heading vs.
      Kicking).

      For non-athletic control cohort, investigators will attempt to recruit 20 subjects who are
      18-26 years old, have never played organized sports, and have never been diagnosed with a
      concussion before. This cohort is to evaluate and account for the soccer players' baseline,
      which may be influenced by a history of repetitive heading and sports participation. This
      group will participate in a single test session that lasts approximately in 1.5 hours. During
      the session, blood draw (4mL, about 1 teaspoon), measure eye movements using an ocular motor
      headset,

      The study consists of 4 data collection time points in a 2-day period. This study design will
      enable to test outcome measures over 3 acute phases.

        -  The 1st test session takes place right before the intervention (soccer heading or
           kicking).

        -  Participants will perform either soccer heading or kicking.

        -  The 2nd test session takes place right after the intervention (soccer heading or
           kicking).

        -  The 3rd test session takes place 2h after the intervention (soccer heading or kicking).

        -  The 4th test session takes place approximately 24h after the intervention.

      A standardized and reliable soccer heading protocol will be used for the experiment. A
      triaxial accelerometer (Triax Technologies) embedded in a head-band pocket and positioned
      back of the head to monitor linear and rotational head accelerations. A JUGS soccer machine
      will be used to simulate a soccer throw-in with a standardized ball speed of 25mph across
      both groups. Soccer players frequently perform this maneuver during practice and game.
      Subjects will stand approximately 40ft away from the machine to perform either the heading or
      kicking. Participants in the heading group perform 10 standing headers with 1 header per
      minute, whereas kicking control group performs 10 kicks. The participants in the heading and
      kicking groups will be instructed to direct the ball back toward the JUGS soccer machine in
      the air.

      During each test session, various assessments will be conducted on each subject. First, the
      post-concussion symptom scale, as a subset of the Sports Concussion Assessment Tool 3, will
      be used as a method of assessing the presence and severity of symptoms. This paper-pencil
      symptom checklist consists of 22 symptoms with 7-point Likert scale per symptom to monitor
      subject's well-being. Next, Antecubital vein blood draws will be performed each test session
      to help determine blood biomarker concentrations. A certified phlebotomist will thoroughly
      clean the elbow surface with an alcohol swab and draw 4 ml of whole blood (approx. 1
      teaspoon) into vacutainer tubes containing EDTA anti-coagulant with 21G butterfly needle. A
      Total of 16 ml blood for the study (4 ml x 4 time points; 3~4 teaspoons). After the blood
      draw, the subject will use gauze to maintain direct pressure for 3 mins and Band-Aid will be
      provided. The whole blood will be centrifuged at 3,000 revolutions per minute for 20 minutes
      at 4°C after 40 mins of coagulation. The plasma will then be divided and transferred into 1
      mL cryovials and flash frozen and stored at -80°C in Exercise Biochemistry lab.

      The subject will then perform eye-movement tasks using the EYE-SYNC headset. This
      visual-tracking protocol has been replicated and validated in a number of concussion and
      sleep deprivation studies, however to investigators' knowledge this study for the first time
      will unravel subconcussive effects. Prior to testing, a Snellen chart will be used to verify
      that the subject has a normal or corrected-to-normal vision (minimum 20/30). The subject will
      be seated in a normally lit room and stabilize the headset with two hands while the elbows
      placed on the desk. The visual stimulus will be presented using a 120-Hz frame rate LCD
      screen in the headset and binocular eye movements will be tracked by a single camera secured
      in the headset. The test stimulus consists of a red circular target, 0.5° diameter in a
      visual angle with a 0.2° black dot in the center. The target moves in a circular clockwise
      trajectory of 10° radius at 0.4 Hz, with the target speed corresponding to 25°/s. The entire
      testing sequence will last approximately 3 mins consisted of a calibration and 2 consecutive
      test runs. Calibration of the eye position is conducted by having the subject fixate on a
      target presented at eight locations on the circular path of the test stimulus and one
      additional fixation point at the center of the circular path. The fixation target was
      presented at these nine locations in a randomized order. Each of the two test runs consists
      of 6 cycles of circular movement corresponding to 15 s in duration per test run. The subject
      will be instructed as "follow the movement of the target as closely as possible."
    

Intervention name(s): Soccer Heading
Intervention type(s): Device
Intervention description(s): Soccer Heading: Subjects stood approximately 40 feet away from a JUGS soccer ball launcher and participated in 10 consecutive soccer headings, separated by one minute intervals.
Soccer Kicking: Subjects stood approximately 40 feet away from a JUGS soccer ball launcher and participated in 10 consecutive soccer kicks, separated by one minute intervals.
Other intervention name(s): Soccer Kicking
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Diagnostic