Objectives: Patients with asthma may feel limited in physical activity (PA). Reduced PA has been demonstrated in asthmatics versus healthy controls, and increasing PA associated with improved asthma outcomes. Obesity is commonly found with difficult-to-control asthma and worsens outcomes. We compared PA levels in participants with difficult-to-control asthma and elevated body mass index (BMI) (DOW group) and two mild-moderate asthma groups: one with BMI <25 kg/m 2 (MHW) and one with BMI ≥25 (MOW). Methods: This cross-sectional study used 7-day recordings from wrist-worn accelerometers to compare PA between groups. Inactive time, light (LPA), moderate-vigorous PA (MVPA) were measured, along with two novel metrics: intensity gradient (IG) reflecting PA intensity, and average acceleration (AA) reflecting PA volume. PA parameters were compared using ANOVA or Kruskall-Wallis testing. Correlation and linear regression analyses explored associations between PA parameters and asthma outcomes. As AA was the PA parameter correlated most closely with asthma-related outcomes, an exploratory analysis compared outcomes in highest and lowest AA quartiles. Results: 75 participants were recruited; 57 accelerometer readings were valid and included in analysis. Inactive time was significantly higher (p < 0.001), and LPA (p < 0.007), MVPA (p < 0.001), IG (p < 0.001) and AA (p < 0.001) all significantly lower in DOW versus MHW and MOW groups, even after adjusting for age and BMI. Quartiles based on AA had significantly different asthma profiles. Conclusions: Overweight/obese participants with difficult-to-control asthma performed less PA, and activity of reduced intensity and volume. Increased AA is associated with improvement in several asthma-related outcomes. Increased PA should be recommended to relevant patients.

Purpose of review Obese asthma is now widely recognized as a phenotype of difficult asthma that is common and less responsive to traditional asthma treatments, so identifying specific treatments is increasingly important. Recent findings Obesity can lead to asthma through a complex relationship of causes including mechanical, inflammatory, metabolic and genetic factors. Exercise programmes including pulmonary rehabilitation, weight loss via dietary restriction, exercise and bariatric surgery, or combinations of all of these can improve quality of life, symptoms, and exercise capacity, with reductions in medication use and exacerbations, and represent tailored treatment for this phenotype of severe difficult to treat asthmatic patients. Summary Exercise programmes and pulmonary rehabilitation, weight loss programmes targeting 5–10% weight loss and bariatric surgery are effective treatments for the obese asthma phenotype.

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Background Difficult-to-control asthma associated with elevated body mass index (BMI) is challenging with limited treatment options. The effects of pulmonary rehabilitation (PR) in this population are uncertain. Methods This is a randomised controlled trial of an eight-week asthma-tailored PR programme versus usual care (UC) in participants with difficult-to-control asthma and BMI ≥ 25 kg/m2. PR comprised two hours of education and supervised exercise per week, with encouragement for two individual exercise sessions. Primary outcome was difference in change in Asthma Quality of Life Questionnaire (AQLQ) in PR versus UC groups between visits. Secondary outcomes included difference in change in Asthma Control Questionnaire-6 (ACQ6), and a responder analysis comparing proportion reaching minimum clinically important difference for AQLQ and ACQ6. Results 95 participants were randomised 1:1 to PR or UC. Median age was 54 years, 60% were female and median BMI was 33.8 kg/m2. Mean  (SD) AQLQ was 3.9 (+/-1.2) and median (IQR) ACQ6 2.8(1.8–3.6). 77 participants attended a second visit and had results analysed. Median (IQR) change in AQLQ was not significantly different: 0.3 (− 0.2 to 0.6) in PR and − 0.1 (− 0.5 to 0.4) in UC, p = 0.139. Mean change in ACQ6 was significantly different: − 0.4 (95% CI − 0.6 to − 0.2) in PR and 0 (− 0.3 to + 0.3) in UC, p = 0.015, but below minimum clinically important difference. In ACQ6 responder analysis, minimum clinically important difference was reached by 18 PR participants (54.5%) versus 10 UC (22.7%), p = 0.009. Dropout rate was 31% between visits in PR group, and time to completion was significantly prolonged in PR group at 94 (70–107) days versus 63 (56–73) in UC, p < 0.001. Conclusions PR improved asthma control and reduced perceived breathlessness in participants with difficult-to-control asthma and elevated BMI. However, this format appears to be suboptimal for this population with high drop-out rates and prolonged time to completion. Trial registration Clinicaltrials.gov. ID NCT03630432. Retrospectively registered, submitted May 26th 2017, posted August 14th 2018.