The Combined Effect of Chronic Cannabis Use and Subconcussive Head Impacts on Brain Health

A standardized and reliable soccer heading protocol will be used for the experiment. A triaxial accelerometer embedded in a head-band pocket and positioned directly below the external occipital protuberance (inion) 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. 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 practice and games. Subjects will stand approximately 40ft away from the machine to perform the heading. Participants perform 20 standing headers with 1 header per 30 seconds. The subjects will be instructed to direct the ball back toward the JUGS soccer machine in the air.