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.

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.