Optimal aerobic exercise intensity and its influence on the effectiveness of exercise therapy in patients with pulmonary arterial hypertension: a systematic review

BACKGROUND: Exercise intensity in exercise training programs is an important determinant of program efficacy, such as improvement in exercise capacity and quality of life (QOL). It is not well known whether differently applied exercise intensities are efficacious when used in exercise-based cardiac rehabilitation programs for patients with pulmonary arterial hypertension (PAH). METHODS: Three databases (PubMed, EMBASE, and CINAHL) were searched with the following inclusion criteria: comparative study of exercise interventions for patients with pulmonary arterial hypertension. Three clinical specialists (a physician, nurse, and exercise physiologist) selected the included articles using the process of systematic review. Included articles were grouped according to aerobic exercise intensity: low, moderate-to-vigorous, and vigorous. The level of evidence for each study was rated using Sackett’s levels of evidence. RESULTS: Of 1,452 studies reviewed, 8 were included according to the inclusion criteria (3 randomized controlled trials (RCTs), 3 prospective studies, and 2 case series). Exercise capacity for a six-minute walk distance (mean: 57.7 m) and QOL improved in the above moderate intensity group, while the low intensity group did not show improvement after intervention. For termination criteria, data obtained from the reviewed articles were not sufficient to suggest any exercise intensity recommendations for patients with pulmonary arterial hypertension. DISCUSSION: The findings in this study suggest that at least moderate aerobic exercise intensity is needed to significantly improve six-minute walk distance and QOL in individuals diagnosed with World Health Organization Group 1 of pulmonary arterial hypertension. There is a need for prospective RCTs comparing different exercise intensities in this patient population.