Cardiorespiratory fitness of asthmatic children and validation of predicted aerobic capacity

Cardiopulmonary fitness in children with asthma versus healthy children

OBJECTIVES

To evaluate, with a cardiopulmonary exercise test (CPET), the cardiopulmonary fitness of children with asthma, in comparison to healthy controls, and to identify the clinical and CPET parameters associated with the maximum oxygen uptake (VO_2max) in childhood asthma.

DESIGN

This cross-sectional controlled study was carried out in CPET laboratories from two tertiary care paediatric centres. The predictors of VO_2max were determined using a multivariable analysis.

RESULTS

A total of 446 children (144 in the asthma group and 302 healthy subjects) underwent a complete CPET. Mean VO_2max was significantly lower in children with asthma than in controls (38.6±8.6 vs 43.5±7.5 mL/kg/min; absolute difference (abs. diff.) of -4.9 mL/kg/min; 95% CI of (-6.5 to -3.3) mL/kg/min; p<0.01) and represented 94%±9% and 107%±17% of predicted values, respectively (abs. diff. -13%; 95% CI (-17 to -9)%; p<0.01). The proportion of children with an impaired VO_2max was four times higher in the asthma group (24% vs 6%, p<0.01). Impaired ventilatory efficiency with increased VE/VCO₂ slope and low breathing reserve (BR) were more marked in the asthma group. The proportion of children with a decreased ventilatory anaerobic threshold (VAT), indicative of physical deconditioning, was three times higher in the asthma group (31% vs 11%, p<0.01). Impaired VO_2max was associated with female gender, high body mass index (BMI), FEV1, low VAT and high BR.

CONCLUSION

Cardiopulmonary fitness in children with asthma was moderately but significantly altered compared with healthy children. A decreased VO_2max was associated with female gender, high BMI and the pulmonary function.

TRIAL REGISTRATION NUMBER

NCT04650464.

Effect of high-intensity interval training in adolescents with asthma: The eXercise for Asthma with Commando Joe's® (X4ACJ) trial

BACKGROUND

Higher levels of cardiorespiratory fitness are associated with reduced asthma severity and increased quality of life in those with asthma. Therefore, the purpose of this study was to evaluate the effectiveness of a 6-month high-intensity interval training (HIIT) intervention in adolescents with and without asthma.

METHODS

A total of 616 adolescents (334 boys; 13.0 ± 1.1 years, 1.57 ± 0.10 m, 52.6 ± 12.9 kg, mean ± SD), including 155 with asthma (78 boys), were recruited as part of a randomized controlled trial from 5 schools (4 control and 1 intervention). The 221 intervention participants (116 boys; 47 asthma) completed 6 months of school-based HIIT (30 min, 3 times per week, 10-30 s bouts at >90% age-predicted maximum heart rate with equal rest). At baseline, mid-intervention, post-intervention, and 3-month follow-up, measurements for 20-m shuttle run, body mass index (BMI), lung function, Pediatric Quality of Life Inventory, Paediatric Asthma Quality of Life Questionnaire, and Asthma Control Questionnaire were collected. Additionally, 69 adolescents (39 boys (of the 36 with asthma there were 21 boys)) also completed an incremental ramp test. For analysis, each group's data (intervention and control) were divided into those with and without asthma.

RESULTS

Participants with asthma did not differ from their peers in any parameter of aerobic fitness, at any time-point, but were characterized by a greater BMI. The intervention elicited a significant improvement in maximal aerobic fitness but no change in sub-maximal parameters of aerobic fitness, lung function, or quality of life irrespective of asthma status. Those in the intervention group maintained their BMI, whereas BMI significantly increased in the control group throughout the 6-month period.

CONCLUSION

HIIT represents an effective tool for improving aerobic fitness and maintaining BMI in adolescents, irrespective of asthma status. HIIT was well-tolerated by those with asthma, who evidenced a similar aerobic fitness to their healthy peers and responded equally well to a HIIT program.

Effect of High-Intensity Training and Asthma on the V˙O2 Kinetics of Adolescents

PURPOSE

High-intensity interval training (HIIT) represents a potent stimulus to the dynamic oxygen uptake (V˙O2) response in adults, but whether the same is evident in youth is unknown. HIIT has also been suggested to place a lower demand on the respiratory system, decreasing the likelihood of exacerbation in those with respiratory conditions, such as asthma.

METHODS

Sixty-nine adolescents (13.6 ± 0.9 yr; 36 asthma) took part, 35 of which (17 asthma) participated in a 30-min HIIT intervention three times a week for 6 months. Each participant completed an incremental ramp test to volitional exhaustion and three heavy-intensity constant work rate tests to determine the dynamic V˙O2, heart rate, and deoxyhemoglobin response at baseline, midintervention, postintervention and at a 3-month follow-up.

RESULTS

There was no influence of asthma at baseline or in response to the intervention. Participants in the intervention group demonstrated a faster V˙O2 time constant (τp) after intervention (intervention: 29.2 ± 5.7 s vs control: 34.2 ± 6.5 s; P = 0.003), with these differences maintained at follow-up (intervention: 32.5 ± 5.5 s vs control: 37.3 ± 8.7 s; P = 0.008). The intervention was associated with a speeding of the concentration of deoxyhemoglobin τ (pre: 20.1 ± 4.7 s vs post: 18.2 ± 4.1 s; P = 0.05) compared with a slowing over the same time period in the control participants (pre: 17.9 ± 4.9 s vs post: 20.1 ± 4.6 s; P = 0.012). Heart rate kinetics were not altered (pre: 46.5 ± 12.2 s vs post: 47.7 ± 11.1 s; P = 0.98).

CONCLUSION

These findings highlight the potential utility of school-based HIIT as a strategy to enhance the V˙O2 kinetics of youth, regardless of the presence of asthma.

Patients with asthma have reduced functional capacity and sedentary behavior

OBJECTIVE

The modified shuttle test is a field test that avoids the ceiling effect, and there are no reports of a multidimensional assessment concerning physical activity in asthmatic patients. Thus, the aim was to evaluate functional capacity by MST, additionally to perform a multidimensional assessment as physical activity in daily life, muscle strength, and cytokine levels in children and adolescents with asthma, and to correlate these variables.

METHOD

This cross-sectional study included volunteers aged between 6 and 18 years who were divided into two groups: asthma group (n=43) that received regular treatment and control group (n=24). Functional capacity was evaluated by distance walked during the MST; physical activity in daily life was evaluated using an accelerometer by the number of steps. Quadriceps femoris strength was evaluated by load cell.

RESULTS

Distance walked was lower for the asthma group (790m [222m]) when compared with the control group (950m [240m]; p=0.007); however, the number of steps was similar between the two groups (asthma group: 7743 [3075]; control group: 7181 [3040]; p=0.41), and both groups were classified as sedentary behavior. There was no difference in muscle strength. Tumor necrosis factor-α differed, but interleukin levels were similar between groups. Quadriceps strength was correlated to distance walked (r=0.62; p<0.001) and tumor necrosis factor-α to the number of steps taken (r=-0.54, p=0.005).

CONCLUSION

Children and adolescents undergoing regular asthma treatment showed reduced functional capacity and sedentary behavior. The lower the quadriceps strength, the shorter the distance walked; the higher the tumor necrosis factor-α levels, the lower their daily physical activity levels.

Associations of physical activity with childhood asthma, a population study based on the WHO - health behaviour in school-aged children survey

Background

Asthma in paediatric populations is one of the highest public health concerns. In this study of children and adolescents, we hypothesized that low levels of physical activity (PA) would show associations with asthma that vary by asthma outcome. The objective was to assess whether PA was associated with ever asthma and/or current asthma.

Methods

Analyses were based on 4824 Danish schoolchildren aged 11–15 years old (48.7% boys) participating in the HBSC survey. The study variables were (1) physician-diagnosed asthma (ever asthma) and (2) physician-diagnosed asthma plus wheezing and/or physician or hospital consultation for wheezing (current asthma). Associations with PA by gender were analysed with multivariate logistic regression using the “variance covariance (vce) cluster” method.

Results

The prevalence of ever asthma was 14.3% (boys) and 12.8% (girls), and that of current asthma was 6.8% (boys) and 7.0% (girls). Boys with current asthma showed important differences in low and high PA. We found inverse associations between low PA and ever asthma, odds ratio [95% confidence interval] male: .55 [.30; .99] and female: .47 [.24; .93], and current asthma, male: .27 [.12; .60] (P linear trend = .007) and female: .32 [.11; .94].

Conclusions

The lowest activity levels showed significant inverse associations with asthma, regardless of the definition. For boys, the more stringent (current asthma) of the two paediatric asthma definitions revealed a significant trend with PA, and the direction of associations shifted to positive as weekly PA increased.

Electronic supplementary material

The online version of this article (10.1186/s40733-018-0042-9) contains supplementary material, which is available to authorized users.

Effects of a pulmonary rehabilitation program on physical capacity, peripheral muscle function and inflammatory markers in asthmatic children and adolescents: study protocol for a randomized controlled trial

Background

Individuals with chronic lung disease are more susceptible to present reduction in exercise tolerance and muscles strength not only due to pulmonary limitations but also due systemic repercussions of the pulmonary disease.

The aim of this study is to assess the physical capacity, peripheral muscle function, physical activity in daily life, and the inflammatory markers in children and adolescents with asthma after pulmonary rehabilitation program.

Method

This is a study protocol of randomized controlled trial in asthmatic patients between 6 to 18 years old. The assessments will be conducted in three different days and will be performed at the beginning and at the end of the protocol. First visit: quality of life questionnaire, asthma control questionnaire, pre- and post-bronchodilator spirometry (400 μcg salbutamol), inflammatory assessment (blood collection), and cardiopulmonary exercise test on a cycle ergometer to determine aerobic capacity. Second visit: assessment of strength and endurance of the quadriceps femoris and biceps brachii muscles with concomitant electromyography to assess peripheral muscle strength. Third visit: incremental shuttle walk test (ISWT) and accelerometer to evaluate functional capacity and physical activity in daily life during 7 days. Then, the volunteers will be randomized to receive pulmonary rehabilitation program (intervention group) or chest physiotherapy + stretching exercises (control group). Both groups will have a supervised session, twice a week, each session will have 60 minutes duration, with minimum interval of 24 hours, for a period of 8 weeks. Intervention group: aerobic training (35 minutes) intensity between 60 to 80 % of the maximum workload of cardiopulmonary exercise testing or of ISWT; strength muscle training will be applied to the quadriceps femoris, biceps brachii and deltoid muscles (intensity: 40 to 70 % of maximal repetition, 3 x 8 repetition); finally the oral high-frequency oscillation device (Flutter®) will be used for 5 minutes. The control group: oral high-frequency oscillation device (Flutter®) for 10 minutes followed by the stretching of upper and lower limbs for 40 minutes. It is expected to observe the improvement in aerobic capacity, physical activity in daily life, muscle strength and quality of life of patients in the intervention group, and reduction in inflammatory markers.

Trial registration

Clinical Trial Number: NCT02383069. Data of registration: 03/03/2015

Development and validation of an automated step ergometer

Laboratory ergometers have high costs, becoming inaccessible for most of the population, hence, it is imperative to develop affordable devices making evaluations like cardiorespiratory fitness feasible and easier. The objective of this study was to develop and validate an Automated Step Ergometer (ASE), adjusted according to the height of the subject, for predicting VO2max through a progressive test. The development process was comprised by three steps, the theoretical part, the prototype assembly and further validation. The ASE consists in an elevating platform that makes the step at a higher or lower level as required for testing. The ASE validation was obtained by comparing the values of predicted VO2max (equation) and direct gas analysis on the prototype and on a, treadmill. For the validation process 167 subjects with average age of 31.24 ± 14.38 years, of both genders and different degrees of cardiorespiratory fitness, were randomized and divided by gender and training condition, into untrained (n=106), active (n=24) and trained (n=37) subjects. Each participant performed a progressive test on which the ASE started at the same height (20 cm) for all. Then, according to the subject's height, it varied to a maximum of 45 cm. Time in each stage and rhythm was chosen in accordance with training condition from lowest to highest (60-180 s; 116-160 bpm, respectively). Data was compared with the student's t test and ANOVA; correlations were tested with Pearson's r. The value of α was set at 0.05. No differences were found between the predicted VO2max and the direct gas analysis VO2max, nor between the ASE and treadmill VO2max (p= 0.365) with high correlation between ergometers (r= 0.974). The values for repeatability, reproducibility, and reliability of male and female groups measures were, respectively, 4.08 and 5.02; 0.50 and 1.11; 4.11 and 5.15. The values of internal consistency (Cronbach's alpha) among measures were all >0.90. It was verified that the ASE prototype was appropriate for a step test, provided valid measures of VO2max and could therefore, be used as an ergometer to measure cardiorespiratory fitness.

The relationship between body mass index, aerobic performance and asthma in a pre-pubertal, population-level cohort

PURPOSE

To assess the relationship between asthma, body mass index (BMI) and aerobic performance, as indicated by a shuttle test.

METHODS

20,577 participants (10,413 boys) from the SportsLinx serial cross-sectional study participated. Parental reports of asthma status and home postcode data were gathered from consent forms. Stature, sitting stature and body mass were measured and BMI, somatic maturity and indices of multiple deprivation scores (IMD) were derived. Performance on the 20 m multi-stage shuttle runs test (20mSRT) was used to estimate cardiorespiratory fitness (CRF).

RESULTS

Asthma [F (1, 17,015) = 82.26, P < 0.01] and gender [F (1, 17,015) = 678.491, P < 0.001] significantly influenced 20mSRT. The addition of BMI, maturity and IMD to the model did not alter these significant effects. There was a significant interaction between 20mSRT and BMI [F (1, 16,723) = 132.80, P < 0.01], with a significant decrease in 20mSRT from the 50th BMI percentile upwards [t (16,699) = 36.88, P < 0.01]. Binary logistic regression revealed gender and 20mSRT to be significant predictors of asthma occurrence; BMI SDS just reached significance whilst maturity and IMD were not significant contributors to the model.

CONCLUSIONS

This study demonstrates the negative influences of low CRF and high BMI on the risk of asthma occurrence in pre-pubertal children. Furthermore, it highlights the significant influence of BMI on CRF, revealing these effects to be manifest considerably below those BMI percentiles conventionally associated with being overweight or obese.

Exercise modality and metabolic efficiency in children

Current exercise prescription guidelines for children recommend at least 60 min of moderate-to-vigorous physical activity every day. However, little is known about the efficacy of different cardiorespiratory exercise modalities prescribed to the pediatric cohort. Sixteen healthy children (8-12 years) completed 5-min trials of treadmill walking, cycling, and elliptical training in a randomized order. The treadmill walking speed was determined from measurements collected during a self-selected walking trial. The workloads for treadmill walking, cycling, and elliptical training were matched (40.3 W). Mechanical efficiency (ME%), perceived exertion (RPE), oxygen uptake, metabolic equivalents, and net energy expenditure were measured. ME% in walking was significantly higher than in cycling (P = 0.001) and elliptical training (P < 0.001), and cycling was significantly higher than elliptical training (P = 0.003). RPE in walking was significantly lower than in elliptical training (P = 0.006) but not from cycling (P = 0.314), and cycling resulted in significantly lower RPE than elliptical training (P = 0.021).

CONCLUSION

Treadmill walking appears to be the most efficacious exercise prescription for otherwise healthy children; however, longitudinal studies need to be implemented to investigate the long-term benefits of each exercise modality.

Predicted aerobic capacity of asthmatic children: a research study from clinical origin

Objective. To compare longitudinally PAC of asthmatic children against that of healthy controls during ten months. Methods. Twenty-eight asthmatic children aged 7-15 years and 27 matched controls each performed six submaximal exercise tests on treadmill, which included a test of EIA (exercise-induced asthma). Predicted aerobic capacity (mLO(2)/min/kg) was calculated. Spirometry and development were measured. Physical activity, medication, and "ever asthma/current asthma" were reported by questionnaire. Results. Predicted aerobic capacity of asthmatics was lower than that of controls (P = 0.0015) across observation times and for both groups an important increase in predicted aerobic capacity according to time was observed (P < 0.001). FEV(1) of the asthmatic children was within normal range. The majority (86%) of the asthmatics reported pulmonary symptoms to accompany their physical activity. Physical activity (hours per week) showed important effects for the variation in predicted aerobic capacity at baseline (F = 2.28, P = 0.061) and at the T4 observation (F = 3.03, P = 0.027) and the analyses showed important asthma/control group effects at baseline, month four, and month ten. Physical activity of the asthmatics correlated positively with predicted aerobic capacity. Conclusion. The asthmatic children had consistently low PAC when observed across time. Physical activity was positively associated with PAC in the asthmatics.