Physiological Responses During Field Walking Tests in Adults with Bronchiectasis.

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 [Formula: see text] 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.

Determinants of Peripheral Muscle Strength and Activity in Daily Life in People With Bronchiectasis.

Background: Bronchiectasis is characterized by a progressive structural lung damage, recurrent infections and chronic inflammation which compromise the exertion tolerance, and may have an impact on skeletal muscle function and physical function. Objective: The purpose of this study was to compare peripheral muscle strength, exercise capacity, and physical activity in daily life between participants with bronchiectasis and controls and to investigate the determinants of the peripheral muscle strength and physical activity in daily life in bronchiectasis. Design: This study used a cross-sectional design. Methods: The participants' quadriceps femoris and biceps brachii muscle strength was measured. They performed the incremental shuttle walk test (ISWT) and cardiopulmonary exercise testing, and the number of steps/day was measured by a pedometer. Results: Participants had reduced quadriceps femoris muscle strength (mean difference to control group = 7 kg, 95% CI = 3.8-10.1 kg), biceps brachii muscle strength (2.1 kg, 95% CI = 0.7-3.4 kg), ISWT (227 m, 95% CI = 174-281 m), peak VO2 (6.4 ml/Kg/min, 95% CI = 4.0-8.7 ml/Kg/min), and number of steps/day (3,332 steps/day, 95% CI = 1,758-4,890 steps/day). A lower quadriceps femoris strength is independently associated to an older age, female sex, lower body mass index (BMI), higher score on the modified Medical Research Council scale, and shorter distance on the ISWT (R2 = 0.449). Biceps brachii strength is independently associated with sex, BMI, and dyspnea (R2 = 0.447). The determinants of number of daily steps were dyspnea and distance walked in ISWT, explaining only 27.7% of its variance. Limitations: Number of steps per day was evaluated by a pedometer. Conclusions: People with bronchiectasis have reduced peripheral muscle strength, and reduced aerobic and functional capacities, and they also are less active in daily life. Modifiable variables such as BMI, dyspnea, and distance walked on the ISWT are associated with peripheral muscle strength and physical activity in daily life.