Physiological responses and adaptations to inversion
Vehrs, Pat Roy
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The purpose of this study was to examine the acute cardiovascular and metabolic responses to passive inversion and inverted exercise, and the physiological adaptations to inversion following an inversion training program. Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), and oxygen consumption (V̇O₂) were measured and recorded in 19 young healthy males (average age 20.31 years) in seven positions: (a) standing passive (STD), (b) inverted passive (INV), (c) standing recovery postinversion (SRPI), (d) standing exercise (SDE), (e) standing recovery poststanding exercise (SRPSE), (f) inverted exercise (INVE), and (g) inverted recovery postinverted exercise (IRPIE). Ten of the subjects participated in a 5-week inversion training program. An ANOVA determined statistical differences in the acute responses of all 19 subjects. Passive inversion elicited significant (p̲ < .05) mean increases in SBP of 28.76 mmHg, DBP of 16.21 mmHg, and V̇O₂ of 0.73 ml·kg·min⁻¹ and a significant decrease (p̲ < .05) in HR of 22.36 bpm compared to STD. The differences were attributed to the hemodynamic effects of inversion. Systolic blood pressure and DBP increased during both STDE and INVE (+18.97/1.03 and +12.2/4.18 mmHg, respectively) and were significantly greater during INVE compared to STDE (p̲ < .05). Inverted exercise HR increased to only 2.05 bpm above the STD rate. Systolic blood pressure and DBP were significantly greater (p̲ < .05) during IRPIE compared with SRPI and SRPSE. In SRPI and SRPSE SBP, DBP, and HR returned to the level observed in the respective passive positions. HR in IRPIE remained elevated above the INV rate. Posttraining results were analyzed using an ANCOVA with the pretraining values as covariates. There were no significant differences in SBP, DBP, HR, and V̇O₂ between the two groups in INV, INVE, and IRPIE following 5 weeks of inversion training. Thus, INV significantly increased SBP, DBP, and V̇O₂ and decreased HR, due primarily to the hemodynamic effect of inversion. Inverted exercise elicited significantly greater SBP and DBP responses than STDE but no physiological adaptations to inversion training occurred.