Seated inversion adversely affects vigilance tasks and suppresses heart rate and blood pressure

Abstract

Background: Inverted positions may arise with emergencies, work or recreational activities. Vigilance which can involve cognition, attention, and decision making is required for activities of daily living, in addition to the avoidance and escape from life threatening situations. Objective: The purpose of this study was to evaluate the effects of an inverted posture on vigilance, heart rate and blood pressure. Methods: Heart rate (HR) and blood pressure (BP), vigilance tasks (Tower of London (ToL), Selective Attention and Response Competition (SARC), Attention Networks Test (ANT)), anxiety and reaction time were assessed with 8 male subjects in an initial seated upright position, followed an inverted posture and returning to an upright position. Results: TOL was 63.4% and 40.7% slower and SARC was 10.4% and 11.7% slower during the inverted condition compared to the pre- and post-inversion upright assessments (p<0.01). There were no significant changes in ANT. Systolic BP (p<0.0001), diastolic BP (p=0.03), and HR (p<0.01) decreased during inversion, whereas anxiety scores increased 25% and 51% compared to pre- and post-inversion upright conditions. Conclusions: Under inverted conditions, vigilance task capabilities and reaction time were significantly hampered. These decrements could substantially impact responses to emergency situations.