Cardiopulmonary exercise test indices of respiratory buffering before and after aerobic exercise training in women with pulmonary hypertension: Differentiation by magnitudes of change in six-minute walk test performance

Abstract

While aerobic exercise training (AET) has generally been shown to improve 6-min walk test (6MWT) distance (6MWD) in patients with pulmonary hypertension (PH), a substantial number of patients appear to adapt differently, with minimal or even negative changes in 6MWT distance being reported.

Purpose: To compare post-aerobic exercise training adaptations in cardiorespiratory functional capacity across three groups of patients with PH: those with high (HI), low (LI) and negative (NEG) post-training increases in 6MWD.

Methods: Participants were 25 females (age 54 ± 11 years; BMI 31 ± 7 kg/m2) who completed a vigorous, 10-week, thrice weekly, supervised treadmill walking exercise program. Cardiopulmonary exercise tests (CPET) and 6MWT were completed before and after training. Ten of the 25 participants were classified as HI (range = 47-143 m), 11 were classified as LI (range = 4-37 m) and 4 were classified as NEG (range = -17 to -53 m).

Results: Peak CPET duration, WR and time to anaerobic threshold (AT) were significantly higher (p < 0.05) after training in both the LI and HI groups but not in the NEG group. There was a significant improvement in VE/VCO2 (p = 0.042), PETCO2 (p = 0.011) and TV (p = 0.050) in the HI group after training, but not in the NEG or LI group.

Conclusion: These findings suggest that sustained ventilatory inefficiency and restricted respiratory buffering may mediate exercise intolerance and impede the ability to adapt to exercise training in some patients with PH.

Keywords: Aerobic exercise training; Pulmonary hypertension; Six-minute walk test.

Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Copyright © 2020. Published by Elsevier Ltd.