START & STOPP in GWI

Gulf War Illness (GWI) veterans were divided into 2 pathophysiological groups based on their orthostatic tachycardia responses after submaximal exercise. Two thirds had normal increases of 10 to 15 beats per minute between recumbent and standing both before and after exercise. These were termed the Stress Test Originated Phantom Perception (STOPP) phenotype. In contrast, one third had increases in heart rate of more than 30 beats per minute indicating that exercise induced postural tachycardia; there were the Stress Test Activated Reversible Tachycardia (START) group. This study aimed to confirm the original findings of Rayhan (2013).