Ventilation Increases with Lower Extremity Venous Occlusion in Young Adults

Abstract

Introduction: Venous distention via infsystolic occlusion of the lower limbs may augment ventilation via stimulation of group III/IV afferent neurons. Purpose: The purpose of this study was to examine the ventilatory response to graded lower extremity venous occlusion during exercise in healthy adults. Methods: Nineteen adults (9 men, 25 ± 5 yr) completed two visits. Visit 1 included a maximal cycle ergometry exercise test. Visit 2 included a 30% peak workload cycle exercise with randomized inflations of bilateral thigh pressure tourniquets to 20, 40, 60, 80, and 100 mm Hg for 2 min each, separated by 2 min of deflation. Three minutes of cycling occurred before cuffing (control [CTL]). Expired minute ventilation (VE), whole body gas exchange, rating of perceived exertion, and dyspnea were measured during each session. Results: VE increased significantly from the control condition (exercise only, CTL) to each occlusion pressure (P < 0.05) with the greatest increase at 100 mm Hg (CTL to 100 mm Hg: 31.5 ± 6.6 to 40.1 ± 10.7 L·min-1). Respiratory rate (RR) increased as well (CTL to 100 mm Hg: 24.8 ± 6.0 to 30.9 ± 11.5 breaths per minute, P < 0.05, condition effect) with no change in tidal volume (P > 0.05). Tidal volume to inspiratory time (VT/TI) increased significantly from the CTL condition to each occlusion pressure (CTL to 100 mm Hg: 1.5 ± 0.3 to 1.8 ± 0.4 L·min-1, P < 0.05, all pressures). Dyspnea and RPE increased with all occlusion pressures from CTL exercise (P < 0.05, all pressures). Conclusions: Our findings suggest that mild-to-moderate venous occlusion of the lower extremity evokes a tachypneic breathing pattern which, in turn, augments VE and perceived breathing effort during exercise.