Physiological Responses During Field Walking Tests in Adults with Bronchiectasis

Abstract

BACKGROUND: Field walking tests are commonly used in patients with chronic pulmonary diseases for assessment of functional capacity. However, the physiological demands and magnitude of desaturation on 6-min walk test (6MWT), incremental shuttle walk test (ISWT), and endurance shuttle walk test (ESWT) have not been investigated in patients with bronchiectasis. The objective of this study was to compare the physiological responses and the magnitude of desaturation of subjects with bronchiectasis when performing the 6MWT, ISWT, and ESWT. METHODS: Thirty-two subjects underwent the 6MWT, ISWT, and ESWT on 3 different days. Pulmonary gas exchange, heart rate, and S-pO2 were measured in all tests. RESULTS: There were no differences in the peak rate of oxygen uptake, ventilation, dyspnea, and leg fatigue between the tests. Equivalent cardiac demand (ie, heart rate at peak) was observed with the 6MWT (137 +/- 21 beats/min) and the ESWT (142 +/- 21 beats/min), but this was lower in the ISWT (135 +/- 19 beats/min) compared to ESWT (P < .05). Most subjects achieved a vigorous exercise intensity (heart rate of 70-90% of predicted) in all tests. There was no difference in desaturation among the tests (6MWT: -6.8 +/- 6.6%, ISWT: -6.1 +/- 6.0%, and ESWT: -7.0 +/- 5.4%). CONCLUSIONS: The 6MWT, ISWT, and ESWT induced similar physiological responses at the peak of exercise, eliciting a vigorous exercise intensity. The magnitude of desaturation was similar across tests. This means these tests can be used interchangeably for evaluation of exercise-induced desaturation.