Ventilation Increases with Lower Extremity Venous Occlusion in Young Adults

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 (V_E), whole body gas exchange, rating of perceived exertion, and dyspnea were measured during each session. Results V_E 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 (R_R) 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 (V_T/T_I) 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 V_E and perceived breathing effort during exercise.