Inaccuracy of estimating peak work rate from six-minute walk distance in patients with COPD.

INTRODUCTION: The cardiopulmonary exercise test (CPET) and the 6-minute walk test (6MWT) are used to prescribe the appropriate training load for cycling and walking exercise in patients with chronic obstructive pulmonary disease (COPD). The primary aims were: (i) to compare estimated peak work rate (Wpeak(estimated)) derived from six existing Wpeak regression equations with actual peak work rate (Wpeak(actual)); and (ii) to derive a new Wpeak regression equation using six-minute walk distance (6MWD) and conventional outcome measures in COPD patients. METHODS: In 2906 patients with COPD, existing Wpeak regression equations were used to estimate Wpeak using 6MWD and a new equation was derived after a stepwise multiple regression analysis. RESULTS: The 6 existing Wpeak regression equations were inaccurate to predict Wpeak(actual) in 82% of the COPD patients. The new Wpeak regression equation differed less between Wpeak(estimated) and Wpeak(actual) compared to existing models. Still, in 74% of COPD patients Wpeak(estimated) and Wpeak(actual) differed more than (±) 5 watts. CONCLUSION: In conclusion, estimating peak work load from 6MWD in COPD is inaccurate. We recommend assessment of Wpeak using CPET during pre-rehabilitation assessment in addition to 6MWT.

No differences in physical activity in (un)diagnosed asthma and healthy controls.

To establish whether asthma affects physical activity levels in children (aged 7-10 years) we evaluated physical activity levels in children with undiagnosed asthma (UDA), diagnosed asthma (DA), and healthy controls (HCs). A cross-sectional community-based study was performed which included a parental questionnaire on their child's respiratory health, and testing of airway reversibility and bronchial hyperresponsiveness (BHR). DA was defined as the parents' confirmation of a physician's diagnosis of asthma in the past 12 months. UDA was defined by asthma symptoms combined with airway reversibility or BHR in children without a physician's diagnosis of asthma. Physical activity was measured during 5 days with an accelerometer and a diary, and with the habitual activity estimation scale which reviews the physical activity during the past 2 weeks. The final study population comprised 1,614 children of whom 81 (5%) had DA, 130 (8%) UDA, and 202 HCs. Baseline FEV(1) % was lowest in children with UDA (UDA FEV(1) 94% predicted, DA FEV(1) 98% predicted, HCs FEV(1) 100% predicted). Using the three methods, no differences were found in the physical activity between children with UDA, DA, and HCs. Childhood asthma does not appear to be associated with a decreased level of daily physical activity in our study population.

Aerobic exercise in adolescents with obesity: preliminary evaluation of a modular training program and the modified shuttle test.

BACKGROUND: Increasing activity levels in adolescents with obesity requires the development of exercise programs that are both attractive to adolescents and easily reproducible. The aim of this study was to develop a modular aerobic training program for adolescents with severe obesity, with a focus on variety, individual targets and acquiring physical skills. We report here the effects on aerobic fitness from a pilot study. Furthermore, we examined the feasibility of the modified shuttle test (MST) as an outcome parameter for aerobic fitness in adolescents with severe obesity. METHODS: Fifteen adolescents from an inpatient body weight management program participated in the aerobic training study (age 14.7 +/- 2.1 yrs, body mass index 37.4 +/- 3.5). The subjects trained three days per week for 12 weeks, with each session lasting 30-60 minutes. The modular training program consisted of indoor, outdoor and swimming activities. Feasibility of the MST was studied by assessing construct validity, test-retest reliability and sensitivity to change. RESULTS: Comparing pretraining and end of training period showed large clinically relevant and significant improvements for all aerobic indices: e.g. VO2 peak 17.5%, effect size (ES) 2.4; Wmax 8%, ES 0.8. In addition, a significant improvement was found for the efficiency of the cardiovascular system as assessed by the oxygen pulse (15.8%, ES 1.6). Construct validity, test-retest reliability and sensitivity to change of the MST were very good. MST was significantly correlated with VO2 peak (r = 0.79) and Wmax (r = 0.84) but not with anthropometric measures. The MST walking distance improved significantly by 32.5%, ES 2.5. The attendance rate at the exercise sessions was excellent. CONCLUSION: This modular, varied aerobic training program has clinically relevant effects on aerobic performance in adolescents with severe obesity. The added value of our aerobic training program for body weight management programs for adolescents with severe obesity should be studied with a randomized trial. This study further demonstrated that the MST is a reliable, sensitive and easy to administer outcome measure for aerobic fitness in adolescent body weight management trials.

Dietary supplementation with multiple micronutrients: no beneficial effects in pediatric cystic fibrosis patients.

BACKGROUND: Cystic fibrosis (CF) patients are subjected to increased oxidative stress due to chronic pulmonary inflammation and recurrent infections. Additionally, these patients have diminished skeletal muscle performance and exercise capacity. We hypothesize that a mixture of multiple micronutrients could have beneficial effects on pulmonary function and muscle performance. METHODS: A double-blind, randomized, placebo controlled, cross-over trial with a mixture of multiple micronutrients (ML1) was performed in 22 CF patients (12.9+/-2.5 yrs) with predominantly mild lung disease. Anthropometric measures, pulmonary function, exercise performance by bicycle ergometry, muscular strength and vitamins A and E were determined. RESULTS: Analysis was performed using the paired Student t-test comparing the change in each parameter during ML1 and placebo. Plasma vitamin E and A levels increased during ML1 when compared to placebo. However, no significant difference between the effect of the ML1 or placebo was observed neither for FEV1, FVC, anthropometry, nor for the parameters for muscle performance. CONCLUSIONS: The micronutrient mixture was not superior to placebo with respect to changes in pulmonary function or muscle performance in pediatric CF patients, despite a significant increase in plasma vitamin E concentrations.

Effects of anaerobic training in children with cystic fibrosis: a randomized controlled study.

BACKGROUND: Children's physical activity patterns are characterized by short-term anaerobic activities. Anaerobic exercise performance in children with cystic fibrosis (CF) has received little attention compared to aerobic performance. This study investigated the effects of anaerobic training in children with CF. DESIGN AND METHODS: Twenty patients were randomly assigned to the training group (TG) [11 patients; mean (+/- SD) age, 13.6 +/- 1.3 years; mean FEV(1), 75.2 +/- 20.7% predicted] or the control group (CG) [9 patients; mean age, 14.2 +/- 2.1 years; FEV(1), 82.1 +/- 19.1% predicted]. The TG trained 2 days per week for 12 weeks, with each session lasting 30 to 45 min. The training program consisted of anaerobic activities lasting 20 to 30 s. The control subjects were asked not to change their normal daily activities. Body composition, pulmonary function, peripheral muscle force, habitual physical activity, aerobic and anaerobic exercise performance, and quality of life were reevaluated at the end of the training program, and again after a 12-week follow-up period. RESULTS: Patients in the TG significantly improved their anaerobic performance, aerobic performance, and quality of life. No significant changes were seen in other parameters, and no improvements were found in CG. After the follow-up period, only anaerobic performance and quality of life in TG were significantly higher compared to pretraining values. CONCLUSIONS: Anaerobic training has measurable effects on aerobic performance (although not sustained), anaerobic performance, and health-related quality of life in children with CF. Therefore, anaerobic training could be an important component of therapeutic programs for CF patients.

Longitudinal determinants of peak aerobic performance in children with cystic fibrosis.

BACKGROUND: Several cross-sectional studies in patients with cystic fibrosis (CF) have shown that nutritional status and lung function are important determinants of peak aerobic capacity (peak oxygen uptake [O(2)peak]). In order to account for individual changes, the aim of this study was to determine the longitudinal relationship of changes in nutritional status, lung function, and O(2)peak in children with CF. DESIGN AND METHODS: Fat-free mass (FFM), lung function, and O(2)peak were assessed in 65 children with CF at baseline (mean +/- SD age, 10.5 +/- 2.9 years; mean FEV(1), 92.6 +/- 20.5%) and again 2 years later. FFM was calculated using skinfold thickness, and O(2)peak was measured using an incremental treadmill test for children < 12 years old or an incremental cycle ergometry test for children > or =12 years old. Lung function was measured before the exercise test. RESULTS: Over the 2-year study period, an increase was found for absolute values of FFM (6.1 kg, p < 0.001), FEV(1) (229 mL, p < 0.001), and O(2)peak (240 mL, p < 0.001), while a decrease was found for predicted values of FEV(1) (- 8.9%, p < 0.001) and O(2)peak (- 4.4%, p < 0.05). DeltaO(2)peak over the 2-year period best correlated with DeltaFEV(1) (r = 0.619, p < 0.001) and to a lesser degree with DeltaFFM (r = 0.506, p < 0.001). Multiple regression analysis demonstrated that DeltaFEV(1) and DeltaFFM explained 47% of the variation of the DeltaO(2)peak over the 2-year period. CONCLUSIONS: Our results show that longitudinal changes in O(2)peak are associated with changes in lung function and to a lesser extent with changes in nutritional status in children with CF. Special consideration should be given to exercise training and nutritional intervention, which might improve long-term clinical outcome in children with CF.