OH is classified as a reduction of at least 20mm/ mg with systolic blood pressure or a reduction of 10 mm/ mg of diastolic blood pressure, and is often measured clinically by the 1-Minute Supine to Stand Test.
Participants were either allocated to the concussion group (n=297), or served as controls (n=214). Subjects in the concussion group were aged 12-18, had sustained a concussion within the past 10 days, and were reviewed at one of the participating hospital concussion clinics. Subjects in the control group were healthy age-, gender- and BMI-matched individuals.
Individuals in both groups underwent a 1-Minute Supine to Stand Test upon clinical visit. Apart from this, any additional symptoms such as vertigo, lightheadedness, changes in blood pressure and heart rate were recorded. Participants in the concussion group were tested at their initial visit and after recovery. The control group was assessed during their routine visit for preseason sport screening.