Encouraging physical activity in pediatric asthma: a case-control study of the wonders of walking (WOW) program

Management of the pediatric patient with asthma and obesity

Asthma and obesity are 2 of the most significant chronic diseases of childhood. Both are major public health problems that have been increasing in prevalence. Obesity increases the risk of developing asthma in children, and in children with asthma, obesity increases asthma severity and morbidity. The nature of this relationship is complex and not fully understood, but some pediatric patients with "obesity-related asthma" may represent a phenotype that differs from the more classical, atopic pediatric asthma. In this review, we investigate and discuss some of the currently available literature regarding treatment for asthma complicated by obesity in the pediatric population. We cover the importance of healthy lifestyle modifications, management of obesity-related comorbidities, and the potential role of nutritional supplementation or modification. We then review recent literature, mostly in adults, investigating the potential role of obesity or diabetes medications in the management of patients with asthma who have obesity. Finally, we discuss some of the necessary next steps before these potential new treatments can be considered as part of the standard clinical management of asthma.

Obese-Asthma Phenotype Self-Management: A Literature Review

PROBLEM

Recent identification of the early-onset obese-asthma phenotype has spurred exploration of ways to promote effective, long-term management behaviors for children with this comorbid presentation. Few studies have examined the needs of children with both asthma and obesity and little is known about optimal management options for this unique population. Therefore, the authors aimed to review, critique, and synthesize existing published research on health-management programs designed for children with comorbid asthma and obesity in order to describe the state of the science and recommend next steps in creating pediatric management programs.

ELIGIBILITY CRITERIA

Articles selected for a full-text review were pediatric-focused, included children with both asthma and obesity diagnoses, and discussed the implementation and evaluation of a management program or the evaluation of a management behavior.

SAMPLE

Fifteen articles were selected for review based on the inclusion criteria.

RESULTS

Studies that included current evidence-based elements had better results than those that did not include such elements.

CONCLUSIONS

Based on this review, it is recommended that researchers use theory based, multicomponent, multimodal, family-focused, behaviorally-based interventions that address systems-level influences, social determinates of health, and children's developmental needs over time. Additionally, there is a need for studies with sample sizes adequate for power analyses that include the youngest children with asthma and obesity.

IMPLICATIONS

The need for effective programs for pediatric obese-asthma phenotype management creates the opportunity for nursing-led research and interventions to foster long-term health promotion for affected children and families.

Levels of physical activity in children and adolescents with asthma: A systematic review and meta-analysis

BACKGROUND

In children and adolescents with asthma, the disease may reduce the perceived capability to participate in physical activity (PA) contributing to an increase in the sedentary lifestyle. The literature is unclear as to whether children and adolescents with asthma differ their PA levels from their healthy peers.

OBJECTIVE

Our objective was to describe the different methods and instruments used to measure PA and to compare the PA levels of children and adolescents with asthma with those of their healthy peers.

STUDY DESIGN

We conducted a systematic review of five databases. We included studies that compared the PA measured by objective and subjective instruments in children and adolescents with asthma versus controls. Two independent reviewers analyzed the studies, extracted the data, and assessed the quality of evidence.

RESULTS

Of the 5966 reports returned by the initial search, 28 articles reporting on 3184 patients were included in the data synthesis. A forest plot showed that both groups had similar values of moderate to vigorous PA (MVPA; mean difference, -0.05 h/day; 95% confidence interval [CI], -0.11-0.01; p = .13), sedentary time (mean difference 0.00 h/day; 95% CI, -0.22-0.23 h/day; p = .99) and steps/day (mean difference 354 steps/day; 95% CI, -563-1270 steps/day; p = .45).

CONCLUSION

Children and adolescents with asthma have similar MVPA, steps/day, and sedentary time compared to the controls. The main instruments used were questionnaires and accelerometers.

Physical activity and sedentary time in children and adolescents with asthma: A systematic review and meta-analysis

The influence of asthma on physical activity (PA) in youth remains equivocal. This review synthesizes the evidence regarding the influence of asthma on PA and sedentary time and evaluates the role of key moderators for this relationship. In accordance with PRISMA guidelines, six electronic databases and gray literature were searched. Primary studies in English were included if they reported device-assessed PA in youth with and without asthma. Random effects meta-analyses examined the effect of asthma on PA and, separately, sedentary time. Mixed-effect meta-regression analyses were conducted using age and sex as moderators, with sub-group comparisons for study quality and asthma diagnosis criteria. Overall, of 3944 citations retrieved, 2850 were screened after the removal of supplication and 2743 citations excluded. Of the 107 full-text publications reviewed, 16 were included in data extraction and analysis, with 15 and five studies included in the PA and sedentary time meta-analyses, respectively. The robust effect size estimate for the influence of asthma on PA and sedentary time was -0.04 [95% CI = -0.11, 0.03] and -0.09 [95% CI = -0.12, -0.06], indicating a non-significant and significant trivial effect, respectively. The effect of asthma on PA levels or sedentary time was not associated with age or sex. Youth with controlled asthma are equally physically (in)active as their healthy peers, with asthma associated with less sedentary time. However, methodological limitations and a paucity of clear methodological reporting temper these conclusions. More rigorous device-based assessments, with a particular focus on sedentary time, and more robust diagnoses of asthma, especially with regard to severity, are needed.

Asthma, body mass and aerobic fitness, the relationship in adolescents: The exercise for asthma with commando Joe's® (X4ACJ) trial

Although an association has been suggested between asthma, obesity, fitness and physical activity, the relationship between these parameters remains to be elucidated in adolescents. Six-hundred and sixteen adolescents were recruited (334 boys; 13.0 ± 1.1years; 1.57 ± 0.10m; 52.6 ± 12.9kg), of which 155 suffered from mild-to-moderate asthma (78 boys). Participants completed a 20-metre shuttle run test, lung function and 7-day objective physical activity measurements and completed asthma control and quality of life questionnaires. Furthermore, 69 adolescents (36 asthma; 21 boys) completed an incremental ramp cycle ergometer test. Although participants with asthma completed significantly fewer shuttle runs than their peers, peak V̇O₂ did not differ between the groups. However, adolescents with asthma engaged in less physical activity (53.9 ± 23.5 vs 60.5 ± 23.6minutes) and had higher BMI (22.2 ± 4.8 vs 20.4 ± 3.7kg·m-2), than their peers. Whilst a significant relationship was found between quality of life and cardiorespiratory fitness according to peak V̇O₂, only BMI was revealed as a significant predictor of asthma status. The current findings highlight the need to use accurate measures of cardiorespiratory fitness rather than indirect estimates to assess the influence of asthma during adolescence. Furthermore, the present study suggests that BMI and fitness may be key targets for future interventions seeking to improve asthma quality of life.

Daily physical activity and lung function decline in adult-onset asthma: a 12-year follow-up study

Background: There is a lack of knowledge on the association between daily physical activity and lung function in patients with asthma.

Objective: This study aims to examine the association between daily physical activity and asthma control, lung function, and lung function decline in patients with adult-onset asthma.

Design: This study is part of Seinäjoki Adult Asthma Study (SAAS), where 201 patients were followed for 12 years after asthma diagnosis. Daily physical activity was assessed at follow-up by a structured questionnaire and used to classify the population into subgroups of low (≤240 min) or high (>240 min) physical activity. Three spirometry evaluation points were used: 1. diagnosis, 2. the maximum lung function during the first 2.5 years after diagnosis (Max_0-2.5), 3. follow-up at 12 years.

Results: High physical activity group had slower annual FEV₁ (p<0.001) and FVC (p<0.018) decline. Additionally, the high physical activity group had higher FEV₁ values at follow-up, and higher FEV₁/FVC ratios at follow-up and diagnosis. There was no difference in BMI, smoking, medication, or frequency of physical exercise between high and low physical activity groups. Differences remained significant after adjustments for possible confounding factors.

Conclusion: This is the first demonstration of an association between long-term FEV₁ decline and daily physical activity in clinical asthma. Low physical activity is independently associated with faster decline in lung function. Daily physical activity should be recommended in treatment guidelines in asthma.

Relationship between physical activity level and psychosocial and socioeconomic factors and issues in children and adolescents with asthma: a scoping review

BACKGROUND

Asthma is a heterogeneous chronic airway disease which may reduce capability for physical activity. In healthy peers, physical activity is influenced by psychosocial and socioeconomic factors. Knowledge about the role of these factors has not been mapped in children and adolescents with asthma.

OBJECTIVE

The main objective of this scoping review was to identify psychosocial and socioeconomic factors associated with physical activity level in children and adolescents with asthma in the literature. The specific objectives were to map the instruments used to measure these factors, report on the construction and validation of these instruments, map psychosocial and socioeconomic issues related to physical activity level reported in qualitative studies, and identify gaps in knowledge about the relationship between psychosocial and socioeconomic factors and physical activity level in children and adolescents with asthma.

INCLUSION CRITERIA TYPES OF PARTICIPANTS

Children and adolescents with asthma aged six to 18 years.

CONCEPT

Psychosocial and socioeconomic factors related to physical activity level and participation.

CONTEXT

All physical activity contexts.

TYPES OF SOURCES

Quantitative and qualitative primary studies in English, with no date limit.

SEARCH STRATEGY

The databases searched included nine major databases for health and sports science, and five databases for unpublished studies. After screening and identification of studies, the reference lists of all identified reports were searched, and forward citation searches were conducted using four databases.

EXTRACTION OF THE RESULTS

The following data were extracted: (a) relevant study characteristics and assessment of physical activity level, (b) instruments used to assess psychosocial and socioeconomic factors, (c) association between physical activity level and these factors, (d) construction and validation of instruments, and (e) psychosocial and socioeconomic issues related to physical activity participation.

PRESENTATION OF THE RESULTS

Twenty-one quantitative and 13 qualitative studies were included. In cross-sectional studies, enjoyment, physical self-concept, self-efficacy, attitudes and beliefs about physical activity and health, psychological distress, health-related quality of life, and social support were more often reported as being correlated with physical activity level. In three studies, the construct validity was assessed by factor analysis and construct reliability tests for the study population. Qualitative studies reported 10 issues related to physical activity participation, and capability and being like peers were most commonly reported. There was no direct evidence that qualitative research informed the development or adjustment of instruments in quantitative studies.

CONCLUSIONS

Seven psychosocial factors correlated with physical activity level; capability and being like peers were the most commonly reported issues. Reports of the construction and validation of instruments were sparse.

Effect of childhood BMI on asthma: a systematic review and meta-analysis of case-control studies

Background

Asthma is a multifactorial syndrome that threatens the health of children. Body mass index (BMI) might be one of the potential factors but the evidence is controversial. The aim of this study is to perform a comprehensive meta-analysis to investigate the association between asthma and BMI.

Methods

Electronic databases including, Web of Science, Pubmed, Scopus, Science Direct, ProQuest, up to April 2017, were searched by two researchers independently. The keywords “asthma, body mass index, obesity, overweight, childhood and adolescence” were used. Random and fixed effects models were applied to obtain the overall odds ratios (ORs) and standardized mean difference (SMD). Heterogeneity between the studies was examined using I² and Cochrane Q statistics.

Results

After reviewing 2511 articles, 16 studies were eligible for meta-analysis according to inclusion/exclusion criteria. A meta-analysis from 11 case-control studies revealed OR of asthma and overweight as OR = 1.64; (95% Confidence Interval (CI): 1.13–2.38) and from 14 case-control studies, OR for asthma and obesity was OR = 1.92 (95% CI: 1.39–2.65), which indicated that risk of asthma in overweight and obese children and adolescence was significantly higher (1.64 and 1.92 times) than that of individuals with (p-value < 0.01 for underweight/normal weight in both cases). Furthermore, there was a significant relationship between asthma and BMI > 85 percentile according to SMD SMD = 0.21; (95%CI: 0.03–0.38; p-value = 0.021).

Conclusions

The results showed a significant relationship between BMI (obesity/overweight) and asthma among children and adolescents. It is important to study the confounding factors that affect the relationship between asthma and BMI in future epidemiological researches.

Electronic supplementary material

The online version of this article (10.1186/s12887-018-1093-z) contains supplementary material, which is available to authorized users.

Step Tracking with Goals Increases Children's Weight Loss in Behavioral Intervention

BACKGROUND

This study examined the influence of step goals with pedometers to improve children's weight loss, physical activity, and psychosocial health during obesity treatment.

METHODS

Overweight and obese children ages 8-17 years (n = 105) participated in a 10-week family-based weight management intervention, including physical activity, nutrition, and behavioral modification. A quasi-experimental design was used to group eight cohorts into three conditions: no pedometer (n = 24), pedometer only (n = 25), and pedometer with step goals (i.e., 500 steps/day weekly increase above baseline; n = 56). Height and weight were measured at baseline and week 10 and used to calculate BMI. Analysis of covariance was performed to examine difference by condition for change in weight, BMI, and BMI z-score, controlling for age and baseline value. Differences in steps per day and psychosocial health were compared between the two pedometer conditions.

RESULTS

Participants were 12.4 ± 2.5 years of age, including 70% girls and 64% African Americans. The pedometer with goals condition significantly reduced BMI (p = 0.02) and BMI z-score (p = 0.01) compared with the no-pedometer group. The pedometer with goals condition significantly increased steps per day (+1185 ± 425 steps/day) compared with the pedometer-only condition (-162 ± 620 steps/day; p < 0.05). Both pedometer groups similarly increased in subjective health and quality of life.

CONCLUSIONS

Providing children with pedometers and individualized step goals was an effective approach to produce weight loss. Further work is needed to increase the strength of interventions to achieve clinically meaningful weight reduction for children with obesity.

Physical activity and asthma control level in children and adolescents

BACKGROUND AND OBJECTIVE

Physical activity is defined as any bodily movement produced by a muscle contraction with increased energy expenditure. The aim of this study was to assess the physical activity, asthma control level, spirometric measurements and quality of life in children and adolescents with asthma.

METHODS

We included all children and adolescents aged 7-17 years who had a diagnosis of atopic asthma and who attended the Pediatric Pulmonology Outpatient Clinic of the State University of Campinas, Brazil. Asthma control levels were evaluated by the Asthma Control Test (ACT). Physical activity was measured using the long version of the International Physical Activity Questionnaire (IPAQ) and by other questions about daily activities at school and at home over the last week. Lung function was assessed by spirometry, both pre- and post-bronchodilator (BD). Quality of life was evaluated using the Paediatric Asthma Quality of Life Questionnaire (PAQLQ).

RESULTS

Out of 100 patients, 60 were classified as presenting with controlled asthma (CA) and 40 as presenting with uncontrolled asthma (UA). In the IPAQ, 29% were classified as sedentary, 17% as active and 54% as very active. There was no significant association between physical activity and the level of asthma control. We found no differences between active and sedentary children and adolescents with asthma in spirometric variables or quality of life.

CONCLUSION

No associations were observed between physical activity and asthma control level, spirometric measurements and quality of life in children and adolescents with asthma.

Associations between asthma, overweight and physical activity in children: a cross-sectional study

Background

Asthma and obesity are highly prevalent in children, and are interrelated resulting in a difficult-to-treat asthma-obesity phenotype. The exact underlying mechanisms of this phenotype remain unclear, but decreased physical activity (PA) could be an important lifestyle factor. We hypothesize that both asthma and overweight/obesity decrease PA levels and interact on PA levels in asthmatic children with overweight/obesity.

Methods

School-aged children (n = 122) were divided in 4 groups (healthy control, asthma, overweight/obesity and asthma, and overweight/obesity). Children were asked to perform lung function tests and wear an activity monitor for 7 days. PA was determined by: step count, active time, screen time, time spent in organized sports and active transport forms. We used multiple linear regression techniques to investigate whether asthma, body mass index-standard deviation score (BMI-SDS), or the interaction term asthma x BMI-SDS were associated with PA. Additionally, we tested if asthma features (including lung function and medication) were related to PA levels in asthmatic children.

Results

Asthma, BMI-SDS and the interaction between asthma x BMI-SDS were not related to any of the PA variables (p ≥ 0.05). None of the asthma features could predict PA levels (p ≥ 0.05). Less than 1 in 5 children reached the recommended daily step count guidelines of 12,000 steps/day.

Conclusion

We found no significant associations between asthma, overweight and PA levels in school-aged children in this study. However, as PA levels were worryingly low, effective PA promotion in school-aged children is necessary.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-016-3600-1) contains supplementary material, which is available to authorized users.

A systematic review of the relationship between asthma, overweight, and the effects of physical activity in youth

PURPOSE

The association of asthma and overweight in youth is well studied. However, the temporal relationship between asthma and overweight, the strength of their association, and mediating factors involved in this relationship remain unclear. This review investigates the relationship between asthma and overweight in youth, while examining the role of physical activity as a mediator.

METHODS

A systematic review of literature was conducted using PubMed and Medline databases. Studies conducted among youth aged 0-18 years, published in English between 2000-2014 were included. The Strengthening the Reporting of Observational Studies in Epidemiology guidelines were consulted to evaluate quality of selected citations.

RESULTS

A comprehensive search yielded 143 studies in PubMed and 133 studies in Medline databases. Of these, 75 studies met the eligibility criteria. The review found varying hypotheses regarding the temporal relationship between asthma and overweight in youth; existing evidence supports the mediation of this association by decreased expenditure of energy due to reduced physical activity. Negative self-perception or parental perception of exercise ability due to asthma symptoms secondary to physical exertion was identified as a determinant of physical activity in asthmatic youth.

CONCLUSIONS

Physical activity likely mediates the relationship between asthma and overweight in youth. Temporality of this relationship remains unclear.

Relationships among obesity, physical activity and sedentary behavior in young adolescents with and without lifetime asthma

OBJECTIVE

To examine the inter-relationships among body mass index (BMI), physical activity, sedentary behavior and gender in urban, low-income, primarily African American young adolescents with or without lifetime asthma.

METHODS

Data were collected in 2002-2004 from 626 12-year old adolescents who were children of women who participated in the New Mother's Study in Memphis, TN (1990-1991). Adolescents with and without asthma were compared on BMI, physical activity and sedentary behavior. Multiple linear regression models were used to examine the association of asthma, gender and BMI with physical activity and sedentary behavior.

RESULTS

Complete data were available for 545 adolescents. Eleven percent of adolescents had lifetime asthma. Asthma and gender were associated with high-intensity physical activity (p < 0.001). Adolescents with asthma participated in less physical activity and girls participated less than boys. Gender was associated with sedentary behavior (p < 0.001): boys used personal computer (pc)/video after school more than girls. Girls with asthma had a higher BMI than girls without asthma (p = 0.027). Boys with asthma were less physically active than boys without asthma (p < 0.05).

CONCLUSIONS

Adolescents with asthma are less physically active than those without asthma and girls are less active than boys. Clinicians who provide care for adolescents with asthma are encouraged to assess physical activity/sedentary behavior and provide guidance that promotes active lifestyles. A longitudinal study is needed to shed light on the unique contribution of asthma separated from the effects of overweight/obesity on physical activity and sedentary behaviors.

Parent-targeted mobile phone intervention to increase physical activity in sedentary children: randomized pilot trial

Background

Low levels of moderate-to-vigorous physical activity are associated with adverse health consequences.

Objective

The intent of the study was to determine the feasibility and efficacy of a 12-week physical activity promotion program targeting children, which was delivered to parents through mobile phones.

Methods

Potential participants were recruited through advertisements placed in the newspaper, local hospitals and schools, and an email listserv. Sedentary children aged 6-10 years were randomly assigned to a minimal (MIG) or intensive (IIG) intervention group. Parents in the MIG were given a goal to increase (within 1 month) and maintain their child’s activity at 6000 pedometer steps/day above their baseline levels and to monitor their child’s steps daily. Parents in the IIG were given the same steps/day and monitoring goals, in addition to text messages and articles containing additional behavioral strategies (based on the Social Cognitive Theory) designed to promote their child’s physical activity. The intervention components were delivered via mobile phone. Anthropometrics, body composition, and questionnaires were administered in a clinic. Children wore a New Lifestyles pedometer (NL-1000) each day throughout the intervention and parents were to monitor their child’s step counts daily.

Results

Out of 59 children who screened for the study, a total of 27 children (mean age 8.7, SD 1.4 years; 56%, 15/27 female; 59%, 16/27 African American) were enrolled and completed the study. Overall, 97.90% (2220/2268; 98.20%, 1072/1092 for MIG; 97.60%, 1148/1176 for IIG) of expected step data were successfully entered by the parent or study coordinator. Parents in the MIG and IIG were sent approximately 7 and 13 text messages per week, respectively, averaged over the course of the study. IIG parents accessed an average of 6.1 (SD 4.4) articles over the course of the intervention and accessed a fewer number of articles in the last month compared to the first 2 months of the study (P=.002). Children in both the MIG and IIG significantly increased their physical activity, averaged over 12 weeks, by 1427.6 (SD 583.0; P=.02) and 2832.8 (SD 604.9; P<.001) steps/day above baseline, respectively. The between group difference was not statistically significant (P=.10; effect size=.40), nor was the group by time interaction (P=.57). Regardless of group assignment, children who significantly increased their physical activity reported greater increases in physical activity enjoyment (P=.003). The number of behavioral articles accessed by IIG parents was significantly correlated with change in children’s steps/day (r=.575, P=.04). Changes in children’s steps/day were unrelated to changes in their body composition, mood, and food intake.

Conclusions

Parent-targeted mobile phone interventions are feasible, yet more intense interventions may be needed to support parents’ efforts to increase their children’s physical activity to levels that approximate national recommendations.

Trial Registration

Clinicaltrials.gov NCT01551108; http://clinicaltrials.gov/show/NCT01551108 (Archived by WebCite at http://www.webcitation.org/6TNEOzXNX).

Moderating effect of gender on the prospective relation of physical activity with psychosocial outcomes and asthma control in adolescents: a longitudinal study

OBJECTIVE

Adolescents with asthma experience more psychosocial and physiological problems compared to their healthy peers. Physical activity (PA) might decrease these problems. This study was the first observational longitudinal study to examine whether habitual PA could predict changes in psychosocial outcomes (i.e., symptoms of anxiety and depression, quality of life [QOL] and stress) and asthma control over time in adolescents with asthma and whether gender moderated these relationships.

METHODS

Adolescents with asthma (N = 253; aged 10-14 years at baseline) were visited at home in the spring/summer of 2012 and 2013. They completed questionnaires assessing their habitual PA, symptoms of anxiety and depression, QOL, perceived stress and asthma control. Path analyses using Mplus were conducted to examine longitudinal relationships among habitual PA, psychosocial outcomes and asthma control (controlled for body mass index, age and gender). Using multi-group analyses, we examined whether gender moderated these relationships.

RESULTS

Path analyses in the total group showed that habitual PA did not predict changes in psychosocial outcomes or asthma control over time. Multi-group analyses showed that gender moderated the relation of habitual PA with anxiety and depression. Habitual PA only significantly predicted a decrease in anxiety and depression over time for girls but not for boys.

CONCLUSIONS

Increasing habitual PA in girls with asthma might decrease their symptoms of anxiety and depression.

Asthma and physical activity in multiracial girls from three US sites

OBJECTIVE

Studies comparing physical activity levels in children with and without asthma have had mixed results. Our objective was to investigate the association between asthma diagnosis and physical activity and to examine differences in these associations by race/ethnicity, weight status and caregiver education.

METHODS

We investigated the association between asthma (defined as report of physician-diagnosed asthma with at least one asthma related symptom) and measures of physical and sedentary activity in a study of 6- to 8-year-old girls in the Breast Cancer and the Environment Research Project. We compared reported activity and pedometer measurements among girls with and without asthma, and examined modification of these associations by race/ethnicity, weight status and caregiver education.

RESULTS

Girls (n = 1182) were included with 33.5% White, 4.8% Asian, 30.6% non Hispanic Black and 30.7% Hispanic. Asthma was present in 16.2% of girls. Overall, 38% of girls reported no participation in organized recreational activities and 58% had >2 h/day of television, video game and computer time combined. Girls with asthma whose parents were less educated reported fewer pedometer steps and less non-scheduled activity than girls without asthma with similar caregiver education level. Among girls with asthma, those on a controller medication had higher levels of sedentary activity and more structured physical activity but were less likely to report high intensity physical activity.

CONCLUSIONS

Among girls whose parents are less educated, girls with asthma may have lower physical activity levels than girls without asthma. Use of a controller medication may be related to physical and sedentary activity.

Physical activity and asthma: a systematic review and meta-analysis

INTRODUCTION

This review aims to give an overview of available published evidence concerning the association between physical activity and asthma in children, adolescents and adults.

METHODS

We included all original articles in which both physical activity and asthma were assessed in case-control, cross-sectional or longitudinal (cohort) studies. Excluded were studies concerning physical fitness, studies in athletes, therapeutic or rehabilitation intervention studies such as physical training or exercise in asthma patients. Methodological quality of the included articles was assessed according to the Newcastle-Ottawa Scale (NOS).

RESULTS

A literature search was performed until June 2011 and resulted in 6,951 publications derived from PubMed and 1,978 publications from EMBASE. In total, 39 studies met the inclusion criteria: 5 longitudinal studies (total number of subjects n = 85,117) with physical activity at baseline as exposure, and asthma incidence as outcome. Thirty-four cross-sectional studies (n = 661,222) were included. Pooling of the longitudinal studies showed that subjects with higher physical activity levels had lower incidence of asthma (odds ratio 0.88 (95% CI: 0.77-1.01)). When restricting pooling to the 4 prospective studies with moderate to good study quality (defined as NOS≥5) the pooled odds ratio only changed slightly (0.87 (95% CI: 0.77-0.99)). In the cross-sectional studies, due to large clinical variability and heterogeneity, further statistical analysis was not possible.

CONCLUSIONS

The available evidence indicates that physical activity is a possible protective factor against asthma development. The heterogeneity suggests that possible relevant effects remain hidden in critical age periods, sex differences, or extremes of levels of physical activity (e.g. sedentary). Future longitudinal studies should address these issues.

Childhood obesity and walking: guidelines and challenges

The development and maintenance of excess body mass in many children is partly attributable to levels of physical activity that are lower than the recommended 60 minutes/day. Walking is a recommended form of physical activity for obese children, due to its convenience and perceived ease of adoption. Unfortunately, studies that have used objective physical activity assessment continue to report low step counts and levels of physical activity in obese children. This may be due to physiological and/or biomechanical factors that make walking more difficult for obese children. The purpose of this review is to highlight the current recommended and measured levels of physical activity for children and to discuss the physiological and biomechanical challenges of walking for obese children that may help explain why these children are not meeting physical activity goals.