Uncovering the Spectrum of Orthostatic Hypotension in Athletes with Spinal Cord Injury: Implications for Diagnosis, Classification, and Performance.

Orthostatic hypotension (OH) is classified into three subtypes based on when blood pressure (BP) drops during an orthostatic challenge: initial (IOH; within <15 seconds), classic (COH; within 3 minutes), and delayed (DOH; after 3 minutes). These subtypes have varying degrees of sympathetic dysfunction. OH subtypes have not been characterized after spinal cord injury (SCI), potentially leaving many undiagnosed. This study determined the prevalence and severity of autonomic impairment across OH subtypes in SCI athletes. Ninety-nine Paralympic athletes with chronic SCI underwent BP and heart rate (HR) assessments while supine and during a sit-up test to classify OH subtypes. Autonomic functions were assessed using the Valsalva maneuver (VM) and by calculating Valsalva ratio (VR), total recovery, pressure recovery time (PRT), and overshoot. Lastly, we examined the distribution of OH across the International Wheelchair Rugby Federation (IWRF) Classification in SCI-rugby athletes. 33.3% of the athletes experienced OH, which included 10.1% with IOH, 9.1% with COH, and 14.1% with DOH. Compared to athletes without OH, those with OH exhibited prolonged PRT (p = 0.02) and blunted overshoot (p = 0.006) during VM. The altered VM metrics were associated with hemodynamic changes during the sit-up test. OH presence was distributed throughout all IWRF classifications. SCI athletes can experience different subtypes of OH that might interfere with sports performance and cognition. Recognizing athletes with DOH is important since this group may be missed if their orthostatic challenge test is terminated early. Evaluation of VM outcomes could supplement an orthostatic challenge to provide valuable insight into autonomic dysfunctions after SCI. Future research is required to check how the presence of OH throughout IWRF classifications can affect performance.