Objective: To determine the occurrence of exercise-induced bronchoconstriction and analyze cardiorespiratory response during maximal exercise in asthmatic patients. Patients and methods: Fourteen subjects with asthma (FEV1 of 86.3% predicted), as defined by the American Thoracic Society criteria were submitted to a maximal exercise test. Volume-flow curves were performed prior to progressive maximal exercise and seven and 15 minutes after it. Six patients (43%) showed a decline in FEV1 equal or greater than 15% after exercise (group I). The remaining patients constituted group II. Group I showed a FEV1 fall of 40.9% and 26.7%, seven and 15 minutes after exercise, respectively. In group II, there was a decrease of 2.6%, after 7 min and an increase of 1.2% after 15 min. At peak exercise, both groups reached heart rate above 91% of reference values; peak work was 82.7% and 62.5%, VO2max (mL/kg/min) 93.5% and 58,9% and VEmax 91.5% and 63.8%, respectively, in groups I and II. These differences were statistically significant. The correlation between the FEV1 fall rate (7 min post-exercise) and VEmax (% predicted) has showed a coefficient r = 0.8989 in group I and r = 0.3629 in group II. There was no correlation between delta VEF1 and VO2max (% predicted) in both groups. These findings showed that, in exercise-induced asthma patients, the occurrence of bronchoconstriction correlated with the level of maximal ventilation, but not with physical fitness.

Keywords: Exercise induced asthma. Bronchoconstriction. Tidal volume. Respiratory function tests.

Objective: To determine the probability of oxygen desaturation in healthy individuals undergoing the incremental shuttle walk test (ISWT). Methods: We enrolled 83 healthy subjects: 55 males (including 1 smoker) and 28 females. We determined pre-ISWT FEV1, FEV6, HR and SpO2, as well as post-ISWT HR and SpO2. Results: Mean values overall were as follows: age, 35.05 ± 12.53 years; body mass index, 24.30 ± 3.47 kg/m2; resting HR, 75.12 ± 12.48 bpm; resting SpO2, 97.96 ± 1.02%; FEV1, 3.75 ± 0.81 L; FEV6, 4.45 ± 0.87 L; FEV1/FEV6 ratio, 0.83 ± 0.08 (no restriction or obstruction); incremental shuttle walk distance, 958.30 ± 146.32 m; post-ISWT HR, 162.41 ± 18.24 bpm; and post-ISWT SpO2, 96.27 ± 2.21%. In 11 subjects, post-ISWT SpO2 was higher than was pre-ISWT SpO2. In 17 subjects, there was a 4% decrease in SpO2 after the ISWT. There were no statistically significant differences between the groups with and without post-ISWT oxygen desaturation in terms of age, gender, FEV1, FEV6, FEV1/FEV6, pre-ISWT SpO2, incremental shuttle walk distance, HR, or percentage of maximal HR. In the individuals with post-ISWT oxygen desaturation, the body mass index was higher (p = 0.01) and post-ISWT SpO2 was lower (p = 0.0001). Conclusions: Healthy individuals can present oxygen desaturation after the ISWT. Using the ISWT to predict subtle respiratory abnormalities can be misleading. In healthy subjects, oxygen desaturation is common after the ISWT, as it is during any intense physical activity.

Keywords: Heart function tests; Respiratory function tests; Body mass index; Oximetry

Objective: One of the common limitations after COVID-19 pneumonia is the decrease in exercise capacity. The identification of the factors affecting exercise capacity and the assessment of patients at risk are important for determining treatment strategy. This study was conducted to determine the predictors of decreased exercise capacity in long post-COVID-19 patients. Methods: We investigated the association of exercise capacity as measured by the incremental shuttle walk test (ISWT) with age, sex, spirometric variables, respiratory and peripheral muscle strength, quality of life, fatigue, hospital anxiety depression scale, chest X-ray involvement, and hospitalization. The patients were divided into three groups: outpatients, inpatients, and ICU patients. Regression analysis was used to determine which parameters were significant predictors of exercise capacity. Results: Of the 181 patients included in the study, 56 (31%) were female. The mean ISWT in percentage of predicted values (ISWT%pred) was 43.20% in the whole sample, whereas that was 52.89%, 43.71%, and 32.21% in the outpatient, inpatient, and ICU patient groups, respectively. Linear regression analysis showed that predictors of decreased ISWT%pred were sex (ß = 8.089; p = 0.002), mMRC scale score (ß = -7.004; p = 0.001), FVC%pred (ß = 0.151; p = 0.003), and handgrip strength (ß = 0.261; p = 0.030). Conclusions: In long post-COVID-19 patients, sex, perception of dyspnea, restrictive pattern in respiratory function, and decrease in peripheral muscle strength are predictors of reduced exercise capacity that persists three months after COVID-19. In this context, we suggest that pulmonary rehabilitation might be an important therapy for patients after COVID-19.

Keywords: COVID-19; Exercise; Muscle strength; Rehabilitation; Walk test.

Objectives: This study primarily aimed to investigate the clinical determinants of the Modified Incremental Step Test (MIST) in adults with non-cystic fibrosis bronchiectasis (NCFB). A secondary objective was to compare the cardiopulmonary responses after the MIST and Incremental Shuttle Walk Test (ISWT), two commonly adopted symptom-limited maximum field tests in chronic respiratory diseases. Methods: Forty-six patients with clinically stable bronchiectasis participated in this cross-sectional study. MIST and ISWT were performed to determine exercise capacity, while disease severity, fatigue, and quality of life were assessed using the Bronchiectasis Severity Index (BSI), the Fatigue Severity Scale (FSS), and St. George's Respiratory Questionnaire (SGRQ), respectively. Quadriceps muscle strength was evaluated using a hand-held dynamometer, walking speed with a wireless inertial sensing device, and the level of physical activity (steps/day) with a pedometer. Results: The BSI score, quadriceps muscle strength, daily step count, and the SGRQ total score explained 61.9% of the variance in the MIST (p < 0.001, R2 = 0.67, AR2 = 0.619). The BSI score (r = -0.412, p = 0.004), quadriceps muscle strength (r = 0.574, p = 0.001), daily step count (r = 0.523, p < 0.001), walking speed (r = 0.402, p = 0.006), FSS score (r = -0.551, p < 0.001), and SGRQ total score (r = -0.570, p < 0.001) correlated with the MIST. The patients achieved higher heart rates (HR), HR%, desaturation, dyspnea, and leg fatigue in the MIST compared to the ISWT (p < 0.05). Conclusions: Disease severity, quadriceps muscle strength, physical activity level, and quality of life were determinants of MIST. The advantages of the MIST, including higher cardiopulmonary response than ISWT and greater portability, which facilitates its use in various settings, make MIST the preferred choice for investigating symptom-limited exercise capacity in patients with NCFB.

Keywords: bronchiectasis, exercise capacity, step test, physical activity, walking speed, quality of life.

Objective: To determine reference values for incremental shuttle walk distance (ISWD) and peak physiological responses during the incremental shuttle walk test (ISWT), as well as to develop a series of predictive equations for those variables in healthy adults. Methods: We evaluated 103 healthy participants ≥ 40 years of age (54 women and 49 men). We fitted each participant with a gas analysis system for use during the ISWT. Oxygen consumption (VO2), carbon dioxide production, minute ventilation, heart rate (HR), ISWD, and maximal walking velocity (MWV) were obtained as primary outcomes. We also assessed hand grip strength (HGS) and lean body mass (LBM). Results: The regression analysis models, including physiological variables, ISWD, and MWV (adjusted for age, body mass, height, and sex), produced R2 values ranging from 0.40 to 0.65 (for HR and peak VO2, respectively). Using the models including LBM or HGS, we obtained no significant increase in the R2 values for predicting peak VO2, although the use of those models did result in slight increases in the R2 values for ISWD and MWV (of 8% and 12%, respectively). The variables ISWD, MWV, and ISWD Î body mass, respectively, explained 76.7%, 73.3%, and 81.2% of peak VO2 variability. Conclusions:áOur results provide reference values for ISWD and physiological responses to the ISWT, which can be properly estimated by determining simple demographic and anthropometric characteristics in healthy adults ≥ 40 years of age. The ISWT could be used in assessing physical fitness in the general adult population and in designing individualized walking programs.

Keywords: Reference values; Pulmonary gas exchange; Walking; Exercise test.